Biophysics in Africa - 2026

23 Mar 2026, 10:00 → 27 Mar 2026, 17:00 Africa/Johannesburg

Bryan Trevor Sewell (University of Cape Town) , Lawrence Norris, Tjaart Krüger (University of Pretoria)

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Conference Schedule

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Topics: Agri-science / Crop Science / Pharmacognosy / Plant biophysics Applied biophysics Astrobiology / Astrochemistry Bioacoustics Bioinfomatics Biomaterials physics Biomechanics Biophotonics Biophysical methods in pharmacology and medicinal chemistry Biophysical methods in pharmaceutics and dosage form design Biophysics and maternal health Biophysics in geosciences Computational biology Electrophysiology / Neuroscience Environmental biophysics Genomics Imaging Industrial biotechnology Mathematical biology Medical biophysics Microscopy Physical biochemistry / Molecular biophysics Physical cell biology / Cellular biophysics Physical methods in paleobiology Quantum biology Small/Wide-angle X-ray scattering in biophysics Soil biophysics Structural biology Development of the future of biophysics in Africa

On March 23, the Biophysical Society will kick off the 11th Annual Biophysics Week. Biophysics Week is a global celebration that brings the biophysics community together while raising awareness of the field and its impact among the public, policy makers, students, and scientists in related fields.

 

 

Tuesday, 24 March

15:00 → 16:30 Featured Invited Talk: Opening Plenary Session: Prof Anita LAYTON

15:00 Opening Plenary Remarks

15:05 We are all different: Modeling key individual differences in physiological systems

Mathematical models of whole-body dynamics have advanced our understanding of human integrative systems that regulate physiological processes such as metabolism, temperature, and blood pressure. For most of these whole-body models, baseline parameters describe a 35-year-old young adult man who weighs 70 kg. As such, even among adults those models may not accurately represent half of the population (women), the older population, and those who weigh significantly more than 70 kg. Indeed, sex, age, and weight are known modulators of physiological function. To more accurately simulate a person who does not look like that "baseline person," or to explain the mechanisms that yield the observed sex or age differences, these factors should be incorporated into mathematical models of physiological systems. Another key modulator is the time of day, because most physiological processes are regulated by the circadian clocks. Thus, ideally, mathematical models of integrative physiological systems should be specific to either a man or woman, of a certain age and weight, and a given time of day. A major goal of our research program is to build models specific to different subpopulations, and conduct model simulations to unravel the functional impacts of individual differences.

Speaker: Prof. Anita LAYTON (University of Waterloo)

Wednesday, 25 March

10:00 → 11:40 Medical Biophysics

10:00 Green-Synthesized Silver Nanoparticle–Liposomal ZnPcS4 Nanoplatform for Enhanced Photodynamic Therapy in Breast Cancer

Breast cancer remains a formidable challenge in oncology despite significant advancements in treatment modalities. Conventional therapies such as surgery, chemotherapy, radiation therapy, and hormonal therapy have been the mainstay in managing breast cancer for decades. However, a subset of patient’s experiences treatment failure, leading to disease recurrence and progression. Therefore, this study investigates the therapeutic potential of green-synthesized silver nanoparticles (AgNPs) using an African medicinal plant (Dicoma anomala methanol root extract) as a reducing agent for combating breast cancer. AgNPs were synthesized using the bottom-up approach and later modified with liposomes (Lip) loaded with photosensitizer (PS) zinc phthalocyanine tetra-sulfonate (Lip@ZnPcS4) using thin film hydration method. The successful formation and Lip modification of AgNPs, alongside ZnPcS4, were confirmed through various analytical techniques including UV–Vis spectroscopy, Fourier-transform infrared spectroscopy (FT-IR), high-resolution transmission electron microscopy (HR-TEM), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Following a 24 h treatment period, MCF-7 cells were assessed for viability using 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT viability assay), cell death analysis using mitochondrial membrane potential (MMP) (ΔΨm), Annexin V-fluorescein isothiocyanate (FITC)-propidium iodide (PI) kit, and caspase- 3, 8 and 9 activities. The experiments were repeated four times (n = 4), and the results were analyzed using SPSS statistical software version 27, with a confidence interval set at 0.95. The synthesized nanoparticles and nanocomplex, including AgNPs, AgNPs-Lip, Lip@ZnPcS4, and AgNPs-Lip@ZnPcS4, exhibited notable cytotoxicity and therapeutic efficacy against MCF-7 breast cancer cells. Notably, the induction of apoptosis, governed by the upregulation of apoptotic proteins i.e., caspase 8 and 9 activities. In addition, caspase 3 was not expressed by MCF-7 cells in both control and experimental groups. Given the challenging prognosis associated with breast cancer, the findings underscore the promise of liposomal nanoformulations in cancer photodynamic therapy (PDT), thus warranting further exploration in clinical settingsemphasized text

Speaker: Alexander Chota (University of Johannesburg, Laser Research Centre)

10:20 Plant based photosensitizers: An in vitro study against cancer cells

Breast cancer remains a major global public health concern due to its continuously rising incidence rate across a variety of demographics. An estimated 2.3 million new cases have made breast cancer higher in incidence rate than the commonly reported lung cancer. Furthermore, women in developing countries have higher mortality rates, 15.3 compared to 11.3 per 100 000 but a much lower incidence rate (30.8 compared to 54.1 per 100,000) associated with women in developed countries. The 5-year breast cancer survival rate in Sub-Saharan Africa is recorded at 40%. Research on cancer treatments has shifted to natural products due to the numerous negative effects of conventional breast cancer treatments, such as chemotherapy, hormone receptor therapy, and surgery. Throughout history, traditional medicine has successfully treated a variety of illnesses with natural ingredients. The variety of plants and their advantages, main and secondary phytocompounds, make them a cost-effective cancer treatment option with few adverse effects. Molecular oxygen, photosensitizer (PS), and light are the three components of photodynamic therapy (PDT), an alternative cancer therapy. Pheophorbide-a and hypericin, two naturally derived PS, were utilized to study the medicinal effects against breast cancer cells. Hypericin is extracted from Hypericum perforatum, while pheophorbide-a is a chlorophyll derivative. This study utilized cell viability assay, flow cytometry, and morphological analysis to evaluate the efficacy of these PSs. MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay showed significant cell death at 0.37 µM for pheophorbide-a and 0.07 µM for hypericin, while morphological analysis showed altered cellular morphology, also confirmed by initiation of apoptosis. Our study shows a promising cost-effective treatment modality for breast cancer due to the fact that it is plant derived.

Speaker: Nosipho Fakudze (University of Johannesburg)

10:40 Photodynamic Therapy against Drug-Resistant Cancer Cells

Photodynamic therapy (PDT) has emerged as a promising alternative or adjunct modality for the treatment of breast cancer. PDT relies on the activation of a photosensitizer (PS) by red or near-infrared light, resulting in the generation of reactive oxygen species (ROS) that induce localized tumor cell damage. Naturally derived tetrapyrrolic PSs have attracted considerable interest due to their favor-able photophysical characteristics. Pheophorbide-a, a chlorophyll-derived tetrapyrrole, demonstrates strong absorption in the red region, efficient singlet oxygen generation, preferential tumor accumula-tion, and minimal dark toxicity. Although Doxorubicin remains one of the most widely used chemo-therapeutic agents for breast cancer treatment, its prolonged administration is associated with the de-velopment of multidrug resistance, largely mediated by P-glycoprotein overexpression. PDT has shown potential efficacy in overcoming chemoresistant phenotypes. In this study, we comparatively evaluat-ed the in vitro phototherapeutic efficacy of pheophorbide-a against wild-type MCF-7 breast cancer cells and Doxorubicin-resistant MCF-7 (MCF-7/DOX) cells using 660 nm light irradiation.

Both cell subtypes were incubated with varying concentrations of pheophorbide-a for 3 h under dark conditions, followed by irradiation with a 660 ± 20 nm LED source at a fluence of 1 J/cm² and a power density of 7.08 mW/cm². Cell viability was assessed 24 h post-irradiation using the MTT assay. The results demonstrated differential sensitivity between the two cell lines. Approximately 90% reduc-tion in cell viability was observed in wild-type MCF-7 cells at 1.6 µM pheophorbide-a, whereas a high-er concentration of 2.4 µM was required to induce a comparable level of cytotoxicity in MCF-7/DOX cells, indicating moderate resistance in the chemoresistant phenotype. Morphological observations further supported these findings. Wild-type MCF-7 cells exhibited significant cellular shrinkage, membrane disruption, and extensive cell death following the PDT. In contrast, MCF-7/DOX cells showed comparatively moderate cytotoxic effects, with approximately 30–40% of cells retaining viable morphology at the same treatment dose.

Overall, pheophorbide-a–mediated PDT demonstrated substantial phototoxic activity against both wild-type and Doxorubicin-resistant breast cancer cells, although higher concentrations were necessary to achieve similar efficacy in resistant cells. These findings suggest that plant-derived chlorophyll-based tetrapyrrolic photosensitizers hold promise as effective PDT agents for targeting multidrug-resistant breast carcinomas. Further mechanistic investigations are required to elucidate the underlying cell death signaling pathways and molecular mechanisms at protein, gene, and transcriptomic levels to enhance translational applicability.

Speaker: Dr Paromita Sarbadhikary (University of Johannesburg)

11:00 Eco-Friendly Gold Nanoparticle-Hypericin Conjugates for Antibody-Mediated Breast Cancer Phototherapy

Abstract
Photodynamic therapy employing Hypericin has gained attention as a potential alternative for breast cancer treatment, yet its clinical utility remains limited by poor solubility, low selectivity, and non-specific cellular uptake. To address these challenges, we developed a targeted nanoplatform integrating green-synthesized gold nanoparticles (AuNPs), Hypericin, and monoclonal antibody functionalisation for enhanced PDT in MCF-7 breast cancer cells.
AuNPs were synthesized using an aqueous extract of Kniphophia porphyrantha, providing a biocompatible and environmentally sustainable route. Hypericin was subsequently loaded onto the AuNP surface, followed by conjugation with a monoclonal antibody to yield a bionanoconjugate with improved targeting capacity. Characterization via UV-Vis spectroscopy, dynamic light scattering, and transmission electron microscopy confirmed nanoparticle formation, photosensitizer loading, and successful antibody attachment.
Therapeutic performance was evaluated through cellular uptake imaging and cytotoxicity assays (MTT, LDH, ATP) alongside flow cytometry following irradiation with a 594 nm diode laser. Free Hypericin reduced cell viability by ~50%, whereas the antibody-conjugated Hypericin-AuNP nanoplatform decreased viability to below 30%. ATP levels dropped by 70% in targeted-nanoconjugate-treated cells compared to only 20% in free Hypericin-treated cells, highlighting enhanced metabolic disruption.
These findings demonstrate that antibody-mediated targeting significantly improves photodynamic efficacy, establishing this green nanotechnology-derived Hypericin-AuNP nanoplatform as a promising candidate for selective breast cancer therapy.

Speaker: Mpho Mohlongo (University of Johannesburg)

11:20 Phototoxicity of Pheophorbide-a in Caco-2 colorectal cancer cells examined through cellular responses and morphological characterisation

Abstract: Photodynamic therapy (PDT) has increasingly been recognised as a promising biomedical strategy for the management of diverse cancers, offering spatial and temporal selectivity compared with conventional chemotherapeutic approaches. However, its therapeutic success is critically dependent on the phototoxic potential of the photosensitiser (Ps) employed and its ability to localise within key cellular compartments and trigger downstream death pathways. In this study, we investigated the phototoxicity of Pheophorbide‑a (PPBa), a chlorophyll‑derived Ps, in Caco‑2 colorectal cancer (CRC) cells under rigorously controlled light and dark conditions to demonstrate its mechanistic effects. Cell viability was assessed using complementary assays that revealed pronounced light‑dependent cytotoxicity, whereas minimal toxicity was observed in the absence of irradiation, emphasising the selectivity of PPBa‑mediated PDT. Subcellular localisation experiments demonstrated preferential accumulation of PPBa within mitochondria, a finding of relevance given the central role of mitochondrial integrity in regulating apoptosis. This localisation correlated strongly with apoptotic signatures, including ATP depletion, nuclear condensation, and programmed cell death pathway activation. Morphological analyses further confirmed phototoxic damage, revealing characteristic features such as cell shrinkage, membrane blebbing, and chromatin condensation. Together with the functional viability data, these structural alterations highlight the potential of PPBa to induce targeted and irreversible damage upon photoactivation. Collectively, our findings provide mechanistic insights into the cellular basis of PPBa‑mediated PDT in CRC cells. By integrating functional viability assays, localisation studies, and morphological characterisation, this work demonstrates the potential of PDT as a selective and effective therapeutic modality for CRC, while also contributing to the broader understanding of Ps‑driven cancer therapy.

Speaker: Mr Fermin Broni (University of Johannesburg)

11:50 → 12:30 Biophysics in Geosciences

11:50 Spatial Distribution and Assessment of Background Ionizing Radiation around Waste Dumpsites in Gombe Metropolis, Nigeria

Waste dumpsites are potential sources of environmental radiation, yet baseline data for many urban centers in northeastern Nigeria remain sparse. This study assessed the background ionizing radiation levels at ten (10) selected waste dumpsites across different land-use categories in Gombe Metropolis, Nigeria. In situ measurements were conducted using a calibrated Medicom CRM-100 Digital Radiation Monitor at a height of 1.0 m above ground level, with geographic coordinates recorded via GPS. The results indicate that the outdoor absorbed dose rates (ADR) ranged from 10.0 ± 1.0 to 23.3 ± 2.3 nGy·h⁻¹, with a mean of 16.7 ± 4.0 nGy·h⁻¹. A spatial variation of 133% was identified between the highest exposure site (Dukku Motor Park) and the lowest (Madaki Quarters), reflecting a correlation between commercial land-use and elevated radiation levels. The estimated annual effective dose rates (AEDR) varied from 0.018–0.041 mSv·y⁻¹, while the excess lifetime cancer risk (ELCR) ranged from (0.70 ± 0.07) × 10⁻⁴ to (1.63 ± 0.16) × 10⁻⁴. The maximum ELCR value corresponds to approximately 16 additional cancer cases per 100,000 persons, which is significantly lower than the WHO global baseline cancer risk and the ICRP public exposure limit of 1 mSv·y⁻¹. The study concluded that current waste disposal practices in the metropolis do not pose an immediate radiological health threat; however, routine monitoring is recommended to detect future deviations in the radiological profile.

Speaker: Muhammad Nuruddeen Abdulkareem (Department of Physics, Federal University of Kashere, Gombe State. Nigeria )

12:10 Petrologic and Geochemical Constraints on the Evolution of Rocks in Southwest Ugep, Southeastern Nigeria

Ugep Southwest is an extension of the Nigerian Basement Complex. It consists of Precambrian crustal rocks that include a succession of deformed metamorphic rocks and non-deformed sedimentary rocks that overlie the basement rocks. The metamorphic rocks are intruded by granodiorites and pegmatites. Gneisses display a sharp contact relationship with the schists, occurring in association with quartzite as observed in Ikot Ekperem. Granodiorites contain enclaves of schistose xenoliths, indicating that magmatic stoping was the mode of emplacement during the Pan-African Orogeny (600 ± 50 Ma). Ugep Southwest has undergone various stages of deformation, as evidenced by complex structures such as folding, faulting, fracturing, lineation, and foliation. The grade of metamorphism was progressive from lower greenschist facies (phyllites and schists) in the west to middle amphibolite facies (gneisses) in the east. Petrological observation using Scanning Electron Microscope (SEM) reveals that the metamorphosed rocks are dominantly composed of plagioclase, biotite, chlorite, and muscovite. Pegmatites have a higher concentration of quartz relative to their magma source. Geochemical analysis using X-ray Fluorescence Spectrometer (XRF) reveals high contents of silica and alumina, implying a crustal origin for the rocks. Barium concentration was higher, suggesting contamination by crustal materials. The geochemistry of these rocks reveals that phyllite and schist are metasediments of pelitic and greywacke composition, while the gneiss is orthogneiss. Granodiorite is calc-alkaline, and the dolerite is tholeiitic. The plots in variation diagrams confirm these geochemical signatures.

Speaker: Ms ADAEZE UGWU (University of Wyoming, USA)

13:00 → 14:40 Medical Biophysics

13:00 A Bioformulated Curcumin–Silver Nanoconjugate for Potent Photodynamic Management of Resistant Lung Cancer

Glory Kah and Heidi Abrahmse*

Laser Research Centre, Faculty of Health Sciences, University of Johannesburg, Doornfontein Campus. Post Office Box 17011, Johannesburg 2028, South Africa

*Correspondence: Heidi Abrahamse. Email: habrahamse@uj.ac.za

Abstract. Lung cancer remains a leading cause of cancer-related mortality worldwide, largely due to therapeutic resistance mediated by lung cancer stem cells (LCSCs). This study aimed to develop and evaluate a bioformulated curcumin–silver nanoparticle conjugate (Cum-PEG-BpAgNPs) for enhanced photodynamic therapy (PDT) targeting both lung cancer cells (A549) and their stem cell subpopulations. Silver nanoparticles were synthesized using Bidens pilosa extract and conjugated with curcumin to form the nanoconjugate, which was subsequently characterized. LCSCs expressing CD133⁺ and CD44⁺ markers were isolated via immunomagnetic bead sorting and confirmed by immunofluorescence. Cellular uptake and subcellular localization were assessed using fluorescence microscopy. Cytotoxicity following dark and 470 nm laser irradiation (5 J/cm²) was evaluated using MTT, LDH, and ATP assays, while reactive oxygen species (ROS) generation, mitochondrial membrane potential disruption, apoptosis–necrosis profiling, and expression of apoptosis-related proteins (p53, caspase-3, and Bcl-2) were analyzed using DCFH-DA, JC-10, Annexin V-FITC/PI, and ELISA assays, respectively. Cum-PEG-BpAgNPs-mediated PDT demonstrated significantly greater cytotoxicity compared to free curcumin, with lower IC₅₀ values in both A549 cells (4.01 µg/mL) and LCSCs (2.37 µg/mL). Enhanced intracellular uptake and broad organelle co-localization were observed for the nanoconjugate. Treatment induced elevated ROS production, mitochondrial dysfunction, and predominantly apoptotic cell death, characterized by upregulation of p53 and caspase-3 and downregulation of Bcl-2. In conclusion, the Cum-PEG-BpAgNPs nanoconjugate significantly improves PDT efficacy against lung cancer cells and resistant LCSCs by promoting ROS-mediated mitochondrial apoptosis, highlighting its potential as a therapeutic strategy for resistant lung cancer.

Speaker: Dr Glory Kah (University of Johannesburg)

13:20 Biogenic Silver Nanoparticles for Visible-Light Activated Breast Cancer Photodynamic Therapy

Silver nanoparticles (AgNPs) offer potent oncological potential via tunable SPR, yet conventional toxicity remains a challenge. This study evaluates biogenic synthesis and photoactivation as safer, targeted alternatives for MCF-7 and MDA-MB-231 breast cancer cells. Specifically, plant-mediated (biogenic) and chemically synthesized AgNPs were evaluated as wavelength-activated nanotherapeutics under matched surface plasmon resonance excitation conditions. Biogenic AgNPs exhibited an SPR maximum at ~466 nm, whereas chemically synthesized AgNPs displayed a peak at ~401 nm. Upon irradiation at 470 nm (biogenic) and 405 nm (chemical) with a fluence of 5 J/cm², distinct photophysical and biological responses were observed.
Chemically synthesized AgNPs demonstrated modest photothermal conversion (ΔT ≈ 2.8 °C), while biogenic AgNPs showed negligible thermal elevation (<1 °C), indicating minimal reliance on hyperthermic mechanisms. However, biogenic AgNPs generated substantially higher photoinduced reactive oxygen species (ROS), producing approximately threefold greater total ROS relative to chemically synthesized counterparts under matched irradiation conditions. This enhanced photo-oxidative activity translated into significant reductions in cell viability. In MCF-7 cells, photoactivation of biogenic AgNPs reduced the IC50 to <2 µg/mL, compared with 2.89 ± 0.20 µg/mL under dark conditions. In MDA-MB-231 cells, irradiation lowered the IC50 from 11.26 ± 0.04 µg/mL (dark) to 4.79 ± 0.05 µg/ml. Flow cytometric analysis confirmed apoptosis as the predominant mechanism of cell death, with late apoptotic populations approaching ~40% following photoactivation.
These results indicate that biogenic AgNPs induce ROS-mediated phototoxicity at lower doses, achieving effective cytotoxicity under visible-light activation without significant thermal effects, supporting their translational potential in cancer treatment.

Speaker: Mr Isaac Baidoo (University of Johannesburg)

13:40 Evaluation of Multifunctional Spinel and Hexaferrite Nanostructures for Magnetic Hyperthermia and Advanced Tumor Therapy

In the present study, a series of magnetic nanoparticles (MNPs) belonging to the spinel ferrite family (XFe2O4 where X = Mg, Cu, Co, Mn) and hexaferrite structures (Ba2Co2Fe12O22 and BaFe12O19) were synthesized using sol-gel and modified co-precipitation methods. The research aims to optimize the structural and physical properties for localized cancer treatment via magnetic hyperthermia. The structural and morphological characteristics were investigated using X-ray diffraction (XRD) and electron microscopy (FE-SEM/TEM), confirming the formation of pure crystalline phases with tailored nanostructures. The optical properties were investigated using UV-visible spectroscopy, revealing a significant dependence of the energy bandgap on the chemical composition and ion substitution. The calculated bandgap values, along with the magnetic parameters obtained from VSM, were correlated to the induction heating performance. Under an alternating magnetic field (150–300 kHz), the specific absorption rate (SAR) values reached up to 350 W/g, particularly in Mn-substituted copper ferrites.
Furthermore, the results indicate that the prepared MNPs, especially the optimized barium hexaferrite (Ba2Co2Fe12O22), exhibit a high potential for inhibiting tumor cell growth when activated by an external magnetic field. These findings highlight the potential of these optimized ferrites as high-performance agents for magnetic hyperthermia and multi-functional biomedical platforms, offering a promising approach for non-invasive thermal therapy.
Keywords:
Magnetic Hyperthermia; Spinel Ferrites; Hexaferrites; substitution; Optical Properties; Bandgap; Specific Absorption Rate (SAR); Tumor Treatment.

Speakers: Diaa EL-Rahman Rayan (Central Metallurgical Research & Development Institute (CMRDI)) , Dr Mahmoud Ismail (Biophysics Branch and Physics Department, Faculty of Science, Al-Azhar University, Nasr City, Cairo, Egypt)

14:00 Advances in MRI techniques for early detection and characterization of brain tumors: A medical physics and biophysical perspective

Early detection of brain tumors is essential for improving clinical outcomes and guiding effective therapeutic interventions. Magnetic Resonance Imaging (MRI) plays a central role in neuro-oncology due to its non-invasive nature and superior soft-tissue contrast. Recent developments in MRI technology, driven by advances in medical physics and biophysical modeling, have significantly improved the sensitivity and specificity of brain tumor detection and characterization. This study reviews key advanced MRI techniques, including diffusion-weighted imaging (DWI), perfusion-weighted imaging (PWI), and functional MRI (fMRI) and their contributions to understanding tumor physiology and microstructure. Diffusion-weighted imaging quantifies the microscopic motion of water molecules, providing biophysical information about cellular density and tissue architecture that helps distinguish tumor tissue from normal brain parenchyma. Perfusion-weighted imaging evaluates tumor vascularity and hemodynamic parameters, offering insights into angiogenesis and tumor grading. Functional MRI utilizes blood-oxygen-level-dependent (BOLD) signal changes to map neural activity, supporting the preservation of critical functional regions during neurosurgical planning. From a medical physics perspective, advancements in MRI acquisition protocols, signal modeling, and quantitative imaging biomarkers have improved image quality, diagnostic reliability, and reproducibility. The integration of these advanced MRI methods provides a comprehensive framework for early tumor detection, improved treatment planning, and monitoring of therapeutic response. Continued progress in MRI physics and biophysical analysis is expected to further enhance the role of imaging in precision neuro-oncology.
Keywords: Medical Physics, biophysics, magnetic resonance imaging, brain tumors, diffusion-weighted imaging, perfusion MRI, functional MRI.

Speaker: Nyasha Njanji (University of Zimbabwe)

14:20 Biophysical Modeling of Real-Time Cellular Mechanical Responses to Ionizing Radiation for Predicting Radiotherapy Outcomes

Medical biophysics continues to expand the understanding of how physical forces and radiation interact with biological systems. While traditional radiobiology focuses mainly on DNA damage and biochemical pathways, the mechanical responses of cells to ionizing radiation remain relatively unexplored. This study proposes a novel approach that investigates how radiation exposure alters the mechanical properties of cancer cells, including cellular stiffness, membrane tension, and cytoskeletal structure.
The research integrates radiation physics with cellular biomechanics to analyze the real-time mechanical responses of cells during irradiation. Advanced biophysical techniques such as atomic force microscopy and high-resolution optical imaging are proposed to measure changes in cell elasticity and deformation after controlled radiation exposure. These measurements are combined with computational modelling to establish correlations between radiation dose deposition and mechanical alterations within the cell.
Preliminary theoretical models suggest that radiation-induced stress can cause rapid cytoskeletal reorganization, leading to measurable changes in cellular mechanical properties before conventional biological markers become detectable. Identifying these mechanical signatures may provide early indicators of cellular radiation damage and radio-sensitivity.
The findings of this study could introduce a new dimension in radiotherapy research by linking radiation–matter interactions with cellular biomechanics. Such insights may contribute to the development of rapid biophysical biomarkers for predicting treatment response and optimizing personalized radiotherapy strategies. Ultimately, this interdisciplinary approach may enhance both the precision and effectiveness of modern cancer treatment.

Keywords: Medical biophysics, cellular biomechanics, ionizing radiation, radiotherapy response, cytoskeleton mechanics, predictive modeling

Speaker: Nyasha Njanji (University of Zimbabwe)

15:00 → 17:00 Biophotonics

15:00 The efficacy of PAM fluorometry as a tool to quantify heat stress in wheat

Fluorescence (spontaneous emission) is a highly sensitive probe for a multitude of molecular processes during the light-dependent steps of photosynthesis in numerous organisms. In living organisms, the fluorescence signal is dwarfed by reflection and scattering; however, the signal-to-noise ratio can be significantly enhanced by gating the fluorescence to sub-msshort excitation pulses through a non-invasive technique known as pulse-amplitude-modulated (PAM) fluorometry. Wheat is an economically important crop that is susceptible to heat stress and consequent yield reduction at temperatures above 30°C. However, the changes to molecular processes that cause the decrease in yield have not been well reported. In this study, PAM fluorometry was used to investigate the effects of high temperatures on the energy transfer pathways during the light-dependent steps of photosynthesis. The quantum efficiency of energy conversion from light to chemical energy was not significantly altered at 30°C but was reduced by 10.7% at 35°C. We show that the biological changes due to the heat shock response to heat stress can be measured at a time resolution of 30 seconds. PAM fluorometry, and thus fluorescence, is able to provide information about the effects of heat stress on electron transport during light-dependent photosynthesis. This opens many possible directions of study, such as investigating the effects of different types of stress on photosynthesis or further modelling the photosynthetic energy-transfer pathways under heat stress.

Speaker: Sarah Burnett (Univeristy of Pretoria)

15:20 BALANCING CELL COMPATIBILITY AND ANTIMICROBIAL EFFECTS OF 470 NM IN AN INFECTED HYPERGLYCAEMIC WOUND CELL MODEL

F.O. Brenya1 and N.N. Houreld1
1Laser Research Centre, University of Johannesburg, Johannesburg, South Africa
E-mail: nhoureld@uj.ac.za
Antimicrobial photobiomodulation (aPBM) with blue light (400-490 nm) is a promising non-invasive adjunct therapy for infected chronic diabetic foot ulcers (DFUs). Still, its fluence-dependent effects on human dermal fibroblasts remain poorly defined. This study investigated the fluence-dependent response of fibroblasts (BJ-5ta) cultured under three conditions: normal (N), normal wounded (NW), and hyperglycaemic wounded (HW), with or without bacterial infection. BJ-5ta fibroblasts (6 × 10⁵ cells/mL) were co-cultured with Staphylococcus aureus, Streptococcus pyogenes, or Pseudomonas aeruginosa (1.5×10³ CFU/mL) and irradiated with 470 nm blue laser light (power output 800 mW; power density 88 mW/cm²) at 5, 10, 30, 55, 100, or 120 J/cm². After 24 hours, fibroblast viability, migration, morphology, and bacterial survival were evaluated. Low fluences (5-10 J/cm²) maintained fibroblast viability at ≥90% across all uninfected models. In contrast, higher fluences (30-120 J/cm²) caused a marked, dose-dependent decrease in fibroblast viability, with the lowest values observed at 120 J/cm² in both normal and hyperglycaemic wounded models. Infection with S. aureus, S. pyogenes, and P. aeruginosa increased cytotoxicity, with each species showing the greatest reduction in fibroblast viability at ≥55 J/cm². Fibroblast migration in the uninfected normal wounded model decreased progressively at fluences over 30 J/cm², dropping to 22-30% at 120 J/cm². In infected normal wounded models, migration declined in a species-dependent manner, with minimum values of 22-30% for S. aureus, 37-48% for S. pyogenes, and 21-27% for P. aeruginosa at 120 J/cm². CFU counts were significantly reduced at 5-10 J/cm² for all species. At 30-120 J/cm², S. aureus and P. aeruginosa were unaffected, whereas S. pyogenes exhibited a sustained, significant decrease in bacterial load. These results suggest a potential therapeutic window at 5-30 J/cm², within which fibroblast function is largely preserved while bacterial burden is reduced, supporting dose-optimised application of 470 nm aPBM in vitro.

Speaker: Mr Francis Obeng Brenya (University of Johannesburg)

15:40 Laser-Based Photobiomodulation Enhances Beta Cell Differentiation and Functional Insulin Production in Immortalised Adipose-Derived Stem Cells

The generation of functional insulin-producing beta (β)-cells from stem cells represented a promising therapeutic strategy for diabetes mellitus. Photobiomodulation (PBM), a non-invasive light-based approach, has emerged as a potential regulator of cellular metabolism, proliferation, and differentiation through mitochondrial stimulation and bioenergetic modulation. This study investigated the effect of laser-based PBM on the differentiation of immortalised adipose-derived stem cells (ADSCs) into functional β-cells under both two-dimensional (2D) and three-dimensional (3D) culture conditions.
Immortalised ADSCs were exposed to defined laser parameters to evaluate their capacity to enhance β-cell lineage commitment and functional insulin production. Cellular health, viability, and metabolic activity were assessed using multiple complementary assays. Intracellular adenosine triphosphate (ATP) quantification determined mitochondrial bioenergetic activity, while lactate dehydrogenase (LDH) release was measured to evaluate cytotoxicity and membrane integrity. Morphological changes associated with differentiation were examined using Giemsa staining, and β-cell-specific insulin granule formation was confirmed using dithizone (DTZ) staining. Additionally, Live/Dead assays were performed to assess overall cell viability and survival within both 2D monolayer and 3D scaffold-based culture systems.
It was hypothesized that laser-based PBM enhanced mitochondrial activity, improved cellular viability, and promoted the generation of metabolically active, insulin-producing β-cells, with enhanced outcomes observed in 3D culture systems due to improved cell–cell and cell–matrix interactions.
This study aimed to advance understanding of laser-based PBM mechanisms in stem cell differentiation and to support the development of non-invasive strategies for β-cell engineering and regenerative diabetes therapies.

Speaker: Olukemi Daramola (University of Johannesburg)

16:00 The artificial optical microscope.

Multimodal optical microscopy has recently converged with artificial intelligence (AI) to the computational prediction of fluorescence‑based molecular
contrast from label‑free measurements. Fluorescence plays a crucial role in linking microscopy and spectroscopy at molecular level, enabling image formation from the cellular to the molecular detail. A challenging development in this field is the coupling of fluorescence with label-free polarization and phase optical methods. We will discuss how this convergence, together with modern generative
modeling for in‑silico labeling, is turning the optical microscope into an intelligent Instrument that we name artificial microscope.

Speaker: Alberto Diaspro (Department of Physics - University of Genoa)

16:20 Parameter study and optimization of real-time single-particle tracking

The real-time tracking of single particles is a vastly under-developed experimental technique but it offers great potential in understanding molecular dynamics. A suitable tracking system comprises three key components, viz., a position sensor, a control system, and an output actuator. The position sensor enables accurate prediction of the particle location. For this component, various tracking methods often employ an estimator of which the scanning pattern is a crucial part. A laser beam is generally scanned in a fixed pattern whilst the photons emitted by the tracked particles are captured and the corresponding photon counts and position coordinates are used to predict the particle location. This process is repeated until some form of termination condition is met. The choice of fixed pattern plays a significant role in the accuracy of the estimator and hence the tracking capabilities of the set-up. In this presentation, we will show how different patterns and detection strategies can be employed in conjunction with accurate two-dimensional single-particle tracking (SPT) simulations of emitting and non-emitting particles to identify an optimal combination. Fluorescence and interferometric scattering (iSCAT) are simulated to represent emitting and non-emitting particles respectively. The performance of each configuration is evaluated using some statistical metrics (e.g., average tracking error).

Speaker: Mr Salomon van Niekerk (University of Pretoria)

16:40 Optimizing Photobiomodulation For Smooth Muscle Differentiation of Adipose-Derived Stem Cells Using Retinoic Acid and TGFβ in a Two-Dimensional Model

Photobiomodulation (PBM) refers to the application of low-level light at specific wavelengths delivered either continuously or in pulses with low and constant energy densities in order to modulate cellular activity. This study investigated the influence of PBM at 525 nm (green), 825 nm (near-infrared; NIR) and a combination wavelength of both on adipose-derived stem cell (ADSC) using assays which assess cellular parameters such as proliferation, viability, mitochondrial function, extracellular matrix (ECM) production, migration and differentiation towards a smooth muscle cell (SMC) in the presence of growth factors like retinoic acid (RA) and transforming growth factor-β (TGF-β). ADSCs were exposed to fluences of 5 J/cm² and 10 J/cm² and assessed using metabolic (ATP), cytotoxicity (LDH), Giemsa for morphology; mitochondrial membrane potential (MMP), collagen quantification, migration analysis and immunofluorescence staining of stemness and SMC associated markers. Morphological analysis demonstrated that ADSCs initially maintained a typical spindle-shaped morphology across all experimental groups. However, fluence-dependent PBM effects became evident over time. Cultures exposed to 5 J/cm² maintained higher cell density and proliferation, whereas 10 J/cm² groups showed sparser cultures and reduced growth, consistent with the biphasic Arndt-Schulz response. ATP analysis supported this trend with lower fluence groups demonstrating enhanced metabolic activity by day 7, while higher fluence groups showed reduced proliferation. LDH levels remained low across all PBM-treated groups, confirming the absence of cytotoxic effects. Mitochondrial analysis indicated a generally stable MMP values during early stages with increased levels at later stages suggesting mitochondrial adaptation during differentiation. Collagen production showed an early increase followed by a decline at later time points, suggestive of ECM remodelling during cellular maturation. Migration analysis revealed differences in cell motility between treatment groups, indicating functional variations associated with PBM exposure. Immunofluorescence confirmed the progressive expression of smooth muscle associated markers including smooth muscle α actin, desmin, calponin and SMMHC during the experimental period. Collectively, these findings demonstrate that PBM modulates ADSC behaviour in a fluence-dependent fashion and may support smooth muscle lineage development under inductive culture conditions further highlighting the potential role of PBM in regenerative medicine applications.

Speaker: Christevie Mbuyu (Laser Research Centre)

Thursday, 26 March

11:00 → 11:45 Featured Invited Talk

11:00 Fluorescence-Lifetime Super-Resolution Microscopy

Recent advancements in super-resolution microscopy have enabled unprecedented insights into the spatial organization of cellular structures. In this talk, I will present a series of methodological innovations that synergistically integrate fluorescence-lifetime single-molecule localization microscopy (FL-SMLM) [1,2], image scanning microscopy (ISM) [3,4], and metal-/graphene-induced energy transfer (MIET/GIET) imaging [5–7]. These approaches collectively offer isotropic three-dimensional resolution at the nanometer scale, multiplexed imaging capabilities, and robustness against chromatic aberrations.

First, I will discuss our work on MIET and GIET microscopy, which exploit distance-dependent quenching phenomena near metallic or graphene interfaces to determine the axial position of single emitters with sub-10 nm accuracy. The combination of MIET with dSTORM or DNA-PAINT provides truly isotropic 3D resolution, extending the reach of localization microscopy into the axial dimension without interferometric complexity.

Second, I will highlight the development of fluorescence lifetime DNA-PAINT (FL-PAINT), a technique that enables multi-target super-resolution imaging through fluorescence lifetime multiplexing without fluid exchange. By utilizing orthogonally designed imager strands conjugated to fluorophores with distinct lifetimes, we achieve simultaneous imaging of multiple targets in the dense intracellular environment.

Lastly, I will introduce our latest development of fluorescence-lifetime image scanning microscopy SMLM (FL-iSMLM), which achieves a near twofold enhancement in lateral resolution by integrating a single-photon detector array into a confocal laser scanning microscope. This method combines the localization precision of ISM with the multiplexing power of fluorescence-lifetime detection, enabling sub-5 nm resolution in fixed cells while simultaneously allowing discrimination of targets based solely on their fluorescence lifetimes.

References
[1] J. C. Thiele, D. A. Helmerich, N. Oleksiievets, R. Tsukanov, E. Butkevich, M. Sauer, O. Nevskyi, and J. Enderlein, Confocal Fluorescence-Lifetime Single-Molecule Localization Microscopy, ACS Nano 14, 14190 (2020).
[2] J. C. Thiele, O. Nevskyi, D. A. Helmerich, M. Sauer, and J. Enderlein, Advanced Data Analysis for Fluorescence-Lifetime Single-Molecule Localization Microscopy, Front. Bioinform. 1, 740281 (2021).
[3] C. B. Müller and J. Enderlein, Image Scanning Microscopy, Phys. Rev. Lett. 104, 198101 (2010).
[4] N. Radmacher, O. Nevskyi, J. I. Gallea, J. C. Thiele, I. Gregor, S. O. Rizzoli, and J. Enderlein, Doubling the resolution of fluorescence-lifetime single-molecule localization microscopy with image scanning microscopy, Nat. Photon. 18, 1059 (2024).
[5] A. I. Chizhik, J. Rother, I. Gregor, A. Janshoff, and J. Enderlein, Metal-induced energy transfer for live cell nanoscopy, Nature Photon 8, 124 (2014).
[6] A. Ghosh, A. Sharma, A. I. Chizhik, S. Isbaner, D. Ruhlandt, R. Tsukanov, I. Gregor, N. Karedla, and J. Enderlein, Graphene-based metal-induced energy transfer for sub-nanometre optical localization, Nat. Photonics 13, 860 (2019).
[7] J. C. Thiele, M. Jungblut, D. A. Helmerich, R. Tsukanov, A. Chizhik, A. I. Chizhik, M. Schnermann, M. Sauer, O. Nevskyi, and J. Enderlein, Isotropic Three-Dimensional Dual-Color Super-Resolution Microscopy with Metal-Induced Energy Transfer, Science Advances 8, 14190 (2021).

Speaker: Prof. Jörg Enderlein (University of Göttingen)

AbstractEnderlein.doc

12:00 → 13:00 Molecular Biophysics

12:00 Multi-timescale fluorescence correlation spectroscopy of the main plant light-harvesting complex during aggregation stages

Light-Harvesting Complex II (LHCII) is the most abundant photosynthetic membrane pigment-protein complex in higher plants, enabling extremely efficient solar energy harvesting. Their light-harvesting function is finely controlled by processes that switch the complexes into a photoprotective state. LHCII aggregates, that feature strong quenching of excitation light, are often believed to be enhance a plant’s photoprotective capability. Finding new ways to study these aggregates can lead to important insights into the fundamental mechanisms by which plants protect themselves against high sunlight intensities, which could, for example, inform efforts to improve crop yields in a changing climate. In our project, we have developed techniques that combine fluorescence correlation spectroscopy (FCS) and time-correlated single-photon counting (TCSPC). The aggregation of LHCII was investigated at increasing levels by step-wise removal of detergent from low-concentration purified samples. Applying pulse-interleaved excitation (PIE) enabled advanced FCS to accurately measure translational and estimated rotational diffusion coefficients, yielding the hydrodynamic radii of LHCII during aggregation. Furthermore, extending measurement times and using both pulsed and continuous excitation unveiled photophysics from microseconds down to picosecond timescales. The results show a rich combination of dimensional information and excitation dynamics in these photosynthetic aggregates, highlighting the importance of singlet-triplet annihilation when studying quenching in LHCII.

Speaker: Francois Conradie

12:20 Objective clustering algorithm applied to single-molecule FCP data

Bulk spectroscopic measurements of photosynthetic light-harvesting complexes report ensemble-averaged properties that often obscure the heterogeneity and dynamic behaviour present at the level of individual complexes. Single-molecule fluorescence spectroscopy provides access to this hidden complexity through measurements of fluorescence intensity and lifetime; however, interpreting raw intensity–lifetime distributions can be challenging because broad, overlapping populations frequently appear visually as only one or two states. Fucoxanthin chlorophyll protein (FCP) is the major light-harvesting complex of diatoms and contains Lhcx subunits that are implicated in photoprotection under high-light conditions. We investigated the fluorescence dynamics of FCP complexes under different environmental conditions using single-molecule intensity and lifetime measurements, performing a comparative, pH-dependent study of two FCP types to examine how Lhcx modulates the photoprotective behaviour. To objectively extract the underlying emissive states, Gaussian mixture model (GMM) clustering was applied to the intensity–lifetime distributions. The optimal number of clusters was objectively determined using information criteria (AIC, BIC, ICL) and cluster-quality metrics to ensure statistical robustness. This approach revealed multiple emissive states beyond the simple two-state (quenched/unquenched) interpretation suggested by visual inspection, enabling direct comparison across datasets and highlighting how environmental conditions and Lhcx content influence the accessibility and stability of the various photophysical states within FCP.

Speaker: Michael Lovemore (Univeristy of the Witwatersrand)

12:40 Linker switch mutations between canonical Plasmodium falciparum Hsp70-1 and PfHsp70-z reveal the role of this motif in regulating the functional specialisation of the two chaperones

Of the five malaria-causing species, Plasmodium falciparum accounts for most malaria-related deaths. Central to the survival and infectivity of the parasite is rapid replication coupled to upregulated protein production. Thus, the development of this malaria parasite is supported by the role of several heat shock proteins (Hsps), which facilitate protein folding. P. falciparum Hsp70-1 (PfHsp70-1) and PfHsp70-z are essential molecular chaperones (molecules that assist proteins to fold correctly) that are cytosol-localized. PfHsp70-z belongs to the Hsp110 cluster of Hsp70-like proteins. Whereas PfHsp70-1 serves as a refolding chaperone, PfHsp70-z is restricted to preventing aggregation of proteins in the cell. The structural features underpinning the functional specialization of these chaperones remain elusive. PfHsp70-z possesses a unique linker segment. In the current study, we explored the role of the linker in regulating the functional specialization of the two P. falciparum Hsp70s. Using recombinant forms of PfHsp70-1, PfHsp70-z, and E. coli Hsp70 (DnaK) as well as their linker switch mutant forms, we explored the effects of the linker mutations using circular dichroism, intrinsic and extrinsic fluorescence coupled to biochemical and in cellulo analyses. Our findings demonstrate that the linker of PfHsp70-z modulates global conformation of the chaperone, regulating several functions such as client protein binding, chaperone, and ATPase activities. In addition, as opposed to the flexible linker of PfHsp70-1, the PfHsp70-z linker is rigid, conferring notable conformational stability to this chaperone, making it an effective holdase chaperone. Our findings highlight the role of the linker in regulating the functional specificity of Hsp70. We discuss the implications of our findings to the development of the malaria parasite at the blood stages of the parasite.

Speaker: Prof. Addmore Shonhai (University of Venda)

13:00 → 13:30 Structural Biology

13:00 Structural insights into the DDX11 helicase

Helicases are essential and ubiquitous enzymes, playing a key role in a variety of processes in DNA and RNA metabolism. A subset of helicases play specialised and specific functions by resolving/remodelling a variety of atypical DNA structures, such as G-quadruplexes, triplexes, Holliday junctions, as well as displacement loops (D-loops and R-loops): among those a major role is played by the FeS family. Helicases containing FeS-clusters are ubiquitous but their exact mechanism of action is poorly understood; no structural information is available for some medically-relevant members of the family, like FANCJ, DDX11 and RTEL1.The combination of the intrinsic conformational flexibility, FeS cluster lability and size makes them challenging targets for structural biology.

DDX11 plays an important role in sister-chromatid cohesion, associates with the replisome and is involved in processing non-canonical nucleic acid structures. We have expressed and purified the human protein with an intact FeS cluster and carried out an extensive biochemical characterization. We have collected Cryo-EM data for the protein alone and in complex with a DNA fork: the apo structure is being refined at 3.5 Å resolution and a preliminary 5 Å structure in complex with a DNA fork has been determined. We can clearly see the path of the DNA fork bound to the helicase including the double helix, and the 5’ single strand across the motor domains. Interestingly, in same regions the structure differs significantly from the AlphaFold model.
These structures provide an essential framework to better understand the role of these enzymes.

Speaker: Prof. Silvia Onesti (N/A)

14:00 → 14:45 Featured Invited Talk

14:00 The importance of water in biology - an example of receptor function and implications for optogenetics

Water, in its many states, has a pivotal role in biology. But resolving it at the molecular level has been a challenge. Here, we resolve and describe how water determines the way in which an external stimulus, light in this example, intimately controls how the stimulus is conformational changes in membrane receptors in response to a stimulus, and capturing their functionally relevant dynamics, is very challenging. Over the years we have addressed this challenge using a range of spectroscopic approaches [1,2,3] on functionally competent photoreceptors, often in their natural membranes [4] or Lipodisqs™ [5,6]. More recently, we have complemented this work with functional studies, mass spec characterization [7] and very high resolution (1.07 Å) crystallography [8,9,10], as well as photo-induced x-ray, free electron laser studies (XFELS), without the use of detergents and including natural lipids. This high-resolution information reveals waters and their importance in both receptor activation-desensitization and QM(SCC-DFTB)/MM MD trajectories give information about the activation process. The system studied is achearhodopsin-3 (AR3), a photoreceptor utilized widely in optogenetics despite the lack of structures until now. We suggest that the different arrangement of internal water networks in AR3 is responsible for the faster photocycle kinetics compared to homologs – AR3 is ~10x more efficient than bacteriorhodopsin at current generation. These insights may well have generic implications for other receptors.

(1). Higman et al., (2011) Angew. Chemie 50(36):8432
(2). Dijkman et al., (2018) Nature Comms. 9:1710
(3). Dijkman et al., (2020) Science Advances, 6:33
(4). Lavington & Watts (2020) Biophys. Rev. 12:1287
(5). Juarez et al., (2019) Chem. Phys. Lipids 221:167
(6). Sawczyc et al (2023) Eur. Biophys J. 52:39
(7). Hoi et al., (2021) Nano Letters, 21(7):2824
(8). Axford et al., (2022) Acta Cryst D78:52
(9). Juarez et al (2021) Nature Comms. 12:629
(10). Birsh et al., (2023) J. Appl. Cryst. 56:1361

Speaker: Prof. Anthony Watts (University of Oxford)

WATTS Abstract.pdf

14:45 → 15:25 Molecular Biophysics

14:45 Production of Leishmania spp. ∆24-sterol methyltransferases for the development of antiparasitic therapies

Parasitic diseases, such as leishmaniasis, pose a growing global health threat, particularly in regions with high HIV/AIDS prevalence [1]. The limited efficacy and growing resistance to current treatments necessitate the discovery of novel therapeutic targets. ∆24-sterolmethyltransferase (SMT) is an attractive target as an essential enzyme in the ergosterol biosynthetic pathway of protozoa and has no mammalian homologue [2]. SMT catalyses the transfer of a methyl group from S-adenosyl-methionine to the C24 position of zymosterol or lanosterol [3]. Structural characterisation of SMTs via X-ray crystallography is crucial for structure-based drug discovery approaches. This study aims to produce and structurally characterise SMTs from Leishmania donovani and Leishmania major to identify lead compounds for antiparasitic therapies.
The ERG6 genes, encoding SMT, from L. donovani and L. major were expressed in E. coli, but resulted in insoluble protein. We then fused ERG6 to genes encoding mCherry or SUMO and successfully expressed the fusions as soluble proteins. The SMTs were cleaved from the fusion partners and purified using column chromatography methods. Furthermore, the purified SMTs have been shown to methylate lanosterol using GC-MS. Biotransformation optimisation is underway to improve conversion yields.
Crystallisation trials using the vapour-diffusion sitting-drop method are currently ongoing. Future work includes collecting X-ray diffraction data of the SMT crystals to solve their three-dimensional structures. The structural information, as well as a robust crystal system, is a prerequisite for X-ray crystallographic fragment screening, which will be used to map SMT binding pockets for inhibitor design.
References
[1] Dangarembizi, R., Wasserman, S., Hoving, J. C., et al. Parasite Immunology, (2023) e12953.
[2] Sakyi, P. O., Kwofie, S. K., Tuekpe, J. K., et al. Pharmaceuticals, (2023) 16(3), 330.
[3] Nes, W.D., Chaudhuri, M., Leaver, D.J. Biomolecules, (2024) 14:249.

Speaker: Bernadette Belter

15:05 Regulation of actin-binding proteins mediated by lipid-protein interactions

The actin cytoskeleton drives membrane deformation during many cellular processes, such as migration, morphogenesis, and endocytosis. Phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2], one of the phosphoinositides, regulates the activities of many actin-binding proteins (ABPs), including profilin, cofilin, Dia2, N-WASP, ezrin, and moesin; however, the underlying molecular mechanisms remain elusive. Here, we applied a combination of biophysical assays and atomistic molecular dynamics simulations to uncover the molecular principles underlying ABP interactions with phosphoinositide-containing membranes. Our results reveal that these proteins show significant differences in membrane interaction dynamics and in the ranges of phosphoinositide densities they can sense. Profilin and cofilin show transient, low-affinity interactions with membranes, whereas F-actin assembly factors Dia2 and N-WASP stay on membranes longer to perform their functions. Ezrin and moesin, which link the actin cytoskeleton to the plasma membrane, bind to membranes with high affinity and slow dissociation kinetics, regulating PI(4,5)P2 lateral diffusion. Unlike profilin, cofilin, Dia2, and N-WASP, they do not require a high ‘stimulus-responsive’ phosphoinositide density for membrane binding. Together, these findings demonstrate that the membrane-interaction mechanisms of ABPs have evolved to precisely fulfill their specific cellular functions in cytoskeletal dynamics.

Speaker: Dr Yosuke Senju

15:25 → 15:50 Quantum Biology

15:25 Identifying Quantum-Relevant Microstates in the Nav1.7 Sodium Channel Pore Using Ensemble Molecular Dynamics Descriptors

Voltage-gated sodium channels are central to neuronal excitability and are major therapeutic targets, yet their functional behavior emerges from highly heterogeneous and dynamically fluctuating pore microenvironments that are difficult to characterize using static structural models alone. In particular, local ion hydration and coordination motifs within the pore can vary substantially over time, potentially modulating energetic sensitivity in ways that are not fully captured by classical force fields. Here, we present a reproducible classical-to-quantum workflow for identifying and prioritizing quantum-relevant microstates in the pore of the human Nav1.7 sodium channel. Using an explicit-solvent molecular dynamics simulation, we extract time-resolved descriptors of the local pore microenvironment, including sodium ion hydration number, oxygen coordination, and spatial occupancy within a protein-centered pore region. These descriptors are used to classify distinct microenvironmental microstates and to construct a qualitative joint-occupancy landscape that highlights recurrent hydration–coordination motifs without invoking fully converged free-energy surfaces. We demonstrate how this ensemble-based microstate analysis can be used to select representative structural clusters for subsequent quantum mechanical treatment, thereby reducing the dimensionality and computational cost of high-level electronic structure calculations such as density functional theory or variational quantum eigensolver (VQE) approaches. Conceptual quantum sensitivity illustrations are included to clarify how different hydration microstates may lead to divergent electronic energetics, motivating targeted quantum refinement. Rather than providing definitive thermodynamic or conductive predictions, this work establishes a practical and extensible framework for bridging long-timescale classical simulations with focused quantum calculations in ion channels. The proposed methodology is broadly applicable to other membrane proteins where transient microenvironmental heterogeneity is expected to play a functional role.

Speaker: Dr Chitaranjan Mahapatra (Korea Advanced Institute of Science & Technology, South Korea)

16:00 → 16:55 Development of the Future of Biophysics in Africa

16:00 International Union for Pure and Applied Biophysics

Speaker: Prof. Anthony Watts (University of Oxford)

16:10 LAAAMP: Light sources for Africa, the Americas, Asia, Middle East and Pacific. Fostering capacity building and collaboration through synchrotron science.

Advanced Light Sources (AdLSs) have been recognized as important large-scale facilities that provide a natural place for international scientific collaboration, capacity building, and networking. The exceptionally intense light produced at these facilities allows scientists to carry out studies of the structure of proteins, of new pharmaceutical compounds, study archaeological objects, design new and better components for technological devices, among many other applications. The establishment of these facilities contributes to boosting the technical and scientific development of the region and to improving the well-being of the general population.

Funding from the International Science Council (ISC) was awarded in 2016 to the joint IUPAP-IUCr project “Utilisation of Light Source and Crystallographic Sciences to Facilitate the Enhancement of Knowledge and Improve the Economic and Social Conditions in Targeted Regions of the World” Later on, the Abdus Salam International Centre for Theoretical Physics (ICTP) and the International Union of Pure and Applied Biophysics (IUPAB) have joined the programme. LAAAMP has carried out different projects aimed at training scientists, particularly early-career researchers in the different aspects of synchrotron-related techniques. The FAculty-STudent (FAST) Teams awards provide funds for a Professor and a Student to spend two months at any of its 18 participating AdLSs. Other activities of LAAAMP have allowed the establishment of crystallography hubs in Benin (X-TechLab) and in Jamaica (crXstal). Similar hubs are planned in other regions for the near future.

LAAAMP coordinates the initiative “Advanced light source facilities to empower Global-South scientists for sustainable development” endorsed by the International Decade of Sciences for Sustainable Development (2024-2033). The aim of this initiative is to promote and establish new AdLSs in Africa, Central Asia, and the Latin America-Caribbean region. In addition, schools, workshops, and conferences are regularly organized and supported by LAAAMP, which will contribute to training and secure future users of AdLSs.

The structure of LAAAMP and the programs developed and supported will be presented. Additional information can be accessed at https://laaamp.iucr.org/.

Speaker: Dr Sizun Christina (French National Centre for Scientific Research)

Poster_LAAAMP_Biophysic_in_Africa2026.docx

16:20 How Instruct-ERIC can help Biophysics in Africa

The study of the structure of biological entities ranging from macromolecules to cells, which underpins most of biophysics, is called Integrated Structural Biology. The field continues to play a key role, not only in biological discovery but also in innovation and technology. Work in the field requires equipment that is specialized and highly developed. The operation and maintenance of such equipment depends on trained and experienced people. The Europeans have found that an effective model, that gives the wider community access to this equipment, is to create facilities to house and operate it. Scientists from member countries can access the equipment, both to learn how to use it and to conduct their own research. The coordination of this process is done through an entity called a European Research Infrastructure Consortium (ERIC), which is funded through subscriptions from the member states. Instruct-ERIC (https://instruct-eric.org/), concerned with Integrated Structural Biology, is currently seeking to expand its footprint by recruiting participation from non-European organizations. Entry-level, cost-free participation involves the signing of an MOU with Instruct, which entitles staff of the affiliate organization to respond to certain funding calls, which will fund the use of the facilities and expertise. At present, the only organization in Africa with such an MOU in place is the University of Cape Town (UCT). UCT is seeking funding from Horizon to increase its level of involvement. Part of the obligation will be to increase national awareness of Instruct-ERIC with the ultimate goal of South Africa becoming a full member. A video introducing the services of Instruct- ERIC is available on YouTube: https://youtu.be/HNwReIQDnhc?si=oYtDz0AXhQqqS1Gt

Speaker: Prof. Bryan Trevor Sewell (University of Cape Town)

17:00 → 18:30 Medical Biophysics: Review of Medical Physics in Africa

17:00 Review of Medical Physics in Africa

This talk is is actually this month's PHYSICS MATTERS presentation of the American Physical Society (APS) Forum on International Physics (FIP).

This talk has its separate registration and Zoom link..

Abstract:
Medical physics (MP) has been an indispensable and strategic stakeholder in the delivery of healthcare in Africa, with immense support to diagnostic radiology (DR), nuclear medicine (NM) and radiotherapy (RT).

There are eleven (11) countries that have MP academic programmes and seven (7) that have clinical training programmes in Africa, by the use of a harmonized curriculum developed by the International Atomic Energy Agency (IAEA), with additional support from the training of medical physicists through the International Centre for Theoretical Physics (ICTP) in Trieste, Italy, where one hundred and twenty-four (124) ICTP medical physics graduates have been trained since 2014/15 to 2023/24 for ten (10) cycles.

The Federation of African Medical Physicist Organisations (FAMPO) was established in 2009, and the Federation’s activities are extended throughout Africa and the local Islands in the Region. FAMPO promotes MP Professional Practice, Education and Training, Research and Development within Africa. FAMPO region has more than 1,200 Medical Physicists for a population of about 1.3 billion. About sixty percent (60%) of MPs are in radiotherapy (RT); 30% in Medical Imaging; 10% in Research & Industry. With respect to Medical Physicist recognition in Africa, only six (6) of the fifty-four (54) African countries have legislative recognition for MPs.

For the future, FAMPO would continue to strengthen collaboration with National Member Organizations and members, advocate for legislative recognition of medical physicists, enhance education and training opportunities for medical physicists, collaborate with key bodies and institutions such as the International Organisation for Medical Physics (IOMP), International Atomic Energy Agency (IAEA), American Association of Physicists in Medicine (AAPM), etc. to bridge the knowledge gap and equip medical physicists with the skills necessary to meet the growing demands of the field.

It is expected that these initiatives and partnerships would promote medical physics profession within the region, strengthen research and innovation within the medical physics community in Africa, enhance legislative recognition, and expand and enhance FAMPO’s network and member engagement.

---

Biography:
Prof. Stephen Inkoom obtained his PhD degree in Medical Physics in 2014 from the University of Ghana. The PhD programme was a sandwich programme between the University of Ghana and University of Crete, Greece with support from the International Atomic Energy Agency (IAEA) and the Government of Ghana.

Prof. Stephen Inkoom is currently a Deputy Director and Chief Research Scientist at the Radiation Protection Institute of the Ghana Atomic Energy Commission. He is also Associate Professor of Medical Physics, School of Nuclear and Allied Sciences, University of Ghana. His work focuses on radiation protection, medical physics, and the safe application of nuclear and accelerator-based technologies in healthcare, reserach and industry. He is actively involved in national and international initiatives supporting capacity building, regulation, and the development of medical physics in Africa, working closely with organizations such as the IAEA and served as a Project Scientific Consultant for IAEA Project RAF9064- Improving the Capabilities of Member States for Radiation Protection of Member States, International Organization for Medical Physics (IOMP), Federation of African Medical Physics Organizations (FAMPO) where He serves as the Secratray General, and others to strengthen education, research, and clinical practice of medical physics and radiation protection across the region. As Project Coordinator for the NORPART Project, 20+ Masters and PhD Students benefitted from Students Exchange Programme for students from Universities in Ghana for an Exchange Stay (2018-2023) at the Norwegian University of Science and Technology (NTNU), Trondheim, Norway in Medical Physics and Radiation Protection Education. Additionally, 500+ trainees benefited from Annual Summer Schools in Ghana (2016 – 2023) in Medical Physics and Radiation Protection Education. He has mentored 50+ Medical Physics students from Africa, and been playing a Leading role in Medical Physics education and training in Africa. Prof. Stephen Inkoom has 20 years of experience in radiation protection and medical physics practice, providing leadership and mentorship in education and training, research and professional development both in Africa and globally.

More about PHYSICS MATTERS, https://engage.aps.org/fip/resources/activities/physics-matters

Discover International Engagement page, https://www.aps.org/about/international

and
Free possible APS membership (https://www.aps.org/membership/join/physicists-worldwide)
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Speaker: Prof. Stephen Inkoom (Radiation Protection Institute, Ghana Atomic Energy Commission )

Friday, 27 March

11:10 → 12:30 Biomaterials

11:10 ANTIMICROBIAL AND ANTIOXIDANT ACTIVITY OF ZINC-MODIFIED COCONUT HUSK BIOCHAR

Microbial resistance is increasing the global burden, and the search for non-antimicrobial products useful in environmental as well as biological applications continues. Coconut husk-derived biochar (BC) was synthesised by pyrolysis at 450 °C and then modified by zinc ion exchange to form zinc-loaded biochar (Zn-BC). The structural and morphological characterisation by X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy (FT-IR) revealed the amorphous structure of carbon matrix loaded with adsorbed zinc-based crystalline domains, maintaining the porous microstructure of the biochar. Antimicrobial activity showed no inhibition to BC (MIC > 1 mg mL⁻¹) against all tested microorganisms. Zn-BC showed broad bactericidal and fungicidal activity of minimum inhibitory concentration (MIC) in all the examined organisms (0.5 mg mL⁻¹). Activity ratios (MBC/MIC ≤ 4) proved bactericidal and fungicidal. In addition, Zn-BC exhibited a moderate antioxidant activity compared to that of BC. Zn-BC exhibited up to 67.0 ± 1.5% radical scavenging in the DPPH assay at 5 mg mL⁻¹, and 61.7 ± 2.6% for unmodified biochar. In the ABTS assay, Zn-BC showed concentration-dependent scavenging with an inhibition of 57.6 ± 5.2% at 25 mg mL⁻¹, higher than that of unmodified BC. These findings indicate that zinc modification can convert coconut husk biochar into an effective and versatile material with high antimicrobial and moderate antioxidant activity.

Speaker: Dr Ralph kwakye (university of health and allied sciences)

11:30 In vitro characterisation of electrospun nanofibers for chronic diabetic wounds

Wound healing is a complex process that can be impaired in conditions such as diabetes, leading to chronic wounds. Advanced dressings, including nanofiber-based scaffolds, offer enhanced interaction with the wound environment and support cellular activity. In this study, polycaprolactone (PCL) and gelatin (GEL) nanofibers were fabricated via electrospinning to evaluate their potential for diabetic wound applications in vitro. Morphology was analyzed using field-emission scanning electron microscopy (FESEM), while biocompatibility, porosity, water uptake, and degradability were assessed. Nanofibers supported fibroblast attachment after 24 hours of incubation and demonstrated high porosity, strong water absorption, and controlled degradation. These findings indicate that electrospun PCL/GEL nanofibers are promising candidates for chronic wound management. Future work will focus on antimicrobial drug loading to further enhance their therapeutical potential.

Speaker: Sinesipho Phalaso

11:50 Physicochemical Characterisation and Antibacterial Activities of Cerium Oxide Nanoparticles

Diabetic wounds represent a complex biophysical microenvironment characterised by sustained inflammation, excess reactive oxygenated species, impaired fibroblastic proliferation, and prevalent bacterial infections, particularly P. aeruginosa. Dysregulated redox homeostasis and altered cellular responses in diabetic tissue significantly compromise wound healing. Although conventional therapies, including hormonal regulation, pressure reduction, wound debridement, and antibiotic treatments, have long served as the foundational approach to the management of diabetic wounds, the increased disease recurrence and heightened bacterial progression have highlighted the limitations of traditional methods. Therefore, this study evaluates the biophysical and bacterial interaction between green-synthesised cerium oxide nanoparticles (CeO2 NPs) and both P. aeruginosa bacterial and mammalian wounded cells. The comprehensive physicochemical characterisation will be used to demonstrate the band gap energy, hydrodynamic size, morphological properties, and redox activity. Additionally, the biophysical evaluation, including antibacterial assays against P. aeruginosa, will demonstrate a concentration-dependent response mediated through membrane interactions. Moreover, the application of CeO2 NPs in fibroblasts will enhance the viability and proliferative responses under oxidative stress conditions, suggesting restoration of redox equilibrium and improved metabolic activity. These findings support the potential integration of complementary bioenergetic modulation strategies in future investigations. Furthermore, the collective findings will enhance the biophysical understanding of nanobio interactions in diabetic wounds while advocating the advancement of redox-active plant-derived nanoparticles designed for resource-constrained environments.

Speaker: Fezile Motsoene (University of Johannesburg)

12:10 Insights into the Structural Analysis of Caffeine–Oxalic Acid Co-crystals Using High-Resolution PXRD and Computational Refinement

Co-crystallization is a powerful tool in crystal engineering, enabling modification of material and drug properties. While single-crystal methods dominate, many systems crystallize only as powders, requiring alternative approaches. We synthesized the caffeine–oxalic acid cocrystal and applied high-resolution powder X-ray diffraction (PXRD) with computational analysis to assess phase formation, crystallinity, and supramolecular organization. PXRD data were collected on a Bruker D2 diffractometer and analyzed using Diffrac.EVA, Topas, EXPO2014, and DASH, with structural models derived from the Cambridge Structural Database. Thermal analysis (TGA/DSC) was performed to evaluate hydration, phase purity, and decomposition.
PXRD profiles confirmed successful co-crystal formation, distinct from starting materials. Thermal analysis indicated no hydration, with decomposition beginning at 200 °C. Indexing revealed a monoclinic P21/a system consistent with prior reports, with lattice parameters: a = 18.97 Å, b = 14.88 Å, c = 3.27 Å, β = 122.74°. Structure solution via simulated annealing achieved a valid fit (Profile χ² < 2), refined further by Rietveld methods. Hydrogen bonding analysis revealed partial expected interactions, though higher-resolution synchrotron data will be required for full elucidation. This work demonstrates the integrated use of PXRD, computational refinement, and thermal analysis as a practical strategy for investigating co-crystals and inclusion complexes in early-stage solid-form screening.

Speaker: Mr Sihle Thabethe (University of Cape Town)

12:30 → 13:40 Computational Biology

12:30 Steroidal Pregnanes as 11β-HSD1 Modulators: Insights from Random Forest-Based QSAR and Atomistic Simulations

The enzyme 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) is a validated therapeutic target for Type 2 diabetes mellitus due to its role in local regeneration of active glucocorticoids. Current inhibitors are often limited by their constrained chemical diversity, moderate potency, and off-target effects. The therapeutic potential of steroidal pregnanes in diabetes and metabolic disorders is been widely reported; however, their molecular targets, particularly in glucocorticoid signaling, remain poorly understood. This study explored the interactions of a curated library of steroidal pregnanes with 11β-HSD1 using integrated Machine Learning (ML)-based QSAR, molecular docking, 100 ns Molecular Dynamics (MD) simulations, and MM-GBSA binding free energy calculations. Initial exploratory chemical space analysis of the IC50 bioactivity dataset revealed that hydrogen donors, molecular weight, and lipophilicity may contribute to the bioactivity of 11β-HSD1 inhibitors. Evaluation of 42 ML algorithms based on performance metrics revealed Random Forest Regressor (RFR) as a top model for bioactivity predictions. Molecular docking simulation of the top RFR-predicted compounds (pIC50 ≥ 6.0 and pKi ≥ 7.8) with the active site of 11β-HSD1 identified three compounds (pregnane-3, 20-diol disulphate (P1), 20-Piperidin-2-yl-5α-pregnan-3β,20-diol (P2), and 12,20-di-O-benzoyl-pregnane-3β,12β,14β,20-tetraol (P3)). While the reference carbenoxolone primarily strongly involved peripheral polar contacts to stabilize its orientation, the pregnane scaffolds demonstrated deeper insertion into the hydrophobic catalytic cavity of 11β-HSD1, resulting in enhanced shape complementarity and van der Waals packing. The thermodynamic parameters computed from the MD simulation trajectories revealed both the structural stability and intrinsic conformational flexibility of the 11β-HSD1–pregnane complexes. Moreover, the lower MM-GBSA binding energies of P1 (-43.58 kcal/mol) and P3 (-44.95 kcal/mol) as compared with the reference carbenoxolone (-24.19 kcal/mol) indicate high binding affinity and validate the docking scores of the hits. Additionally, the leads exhibited favorable physicochemical and pharmacokinetic profiles. Overall, our findings provide mechanistic insights into ligand binding and highlight key structural features that may account for 11β-HSD1 modulation by steroidal pregnanes, offering a framework for the rational design of pregnane-derived therapeutics.

Speaker: Mr Oludare Ogunyemi (University of Ibadan)

Ogunyemi-Abstract.pdf

12:50 Integrating Generative AI, Computational Modeling, and Physiological Reasoning to Enhance Biological Sciences Education

Preparing future biophysicists requires approaches that connect foundational biological principles with modern computational tools. Our work introduces a Generative‑AI–enhanced framework for teaching bioinformatics, designed to strengthen students’ computational reasoning, data literacy, and engagement with cardiovascular‑related biological systems. This model emphasizes ethical and effective integration of AI outputs into analysis and modeling, helping learners navigate emerging digital research environments. Building on this framework, we developed a MATLAB‑based SpO₂ modeling exercise that guides students through finite‑difference modeling of oxygen transport, clinical decision‑making, and the interpretation of physiological data. By incorporating AI‑generated clinical scenarios into MATLAB workflows, students explore realistic diagnostic pathways and deepen understanding of physiological mechanisms. Together, these innovations create an accessible instructional pipeline—particularly valuable for students across the African diaspora—linking computational physiology, cardiovascular innovation, and AI‑supported reasoning. This combined approach broadens participation in biophysics education and offers scalable models for strengthening quantitative and computational skills in the biological sciences.

Speaker: Camellia Okpodu (University of Wyoming)

13:10 Thermomechanical Mapping of DNA under Coupled Salt-Temperature Control with oxDNA2 Coarse-Grained Simulations

Quantifying how temperature and ionic strength jointly determine the elastic properties of double-stranded DNA remains a central challenge in molecular biophysics. Although individual temperature or salt dependent trends have been measured, a unified, mechanistic map across high-salt and elevated-temperature regimes is still lacking. Here, we use the oxDNA2 coarse-grained model to compute a 3×9 thermodynamic ionic grid spanning 300 –373 K and 0.5 – 1.5 M monovalent salt, enabling controlled evaluation of elastic properties and structural observables under conditions where electrostatic screening is extremely strong. Simulations were performed on long 500-bp duplexes with full ensemble averaging over independent replicate trajectories at each condition. Across all salt concentrations, DNA softens as temperature increases, but the degree of softening depends on ionic strength. At 0.5 M, the bending persistence length drops from about 43 nm at 300 K to 32 nm at 373 K. At 1.5 M, the decrease is far smaller (46 → 39 nm), showing that high salt reduces thermal sensitivity by roughly 40–50%. Torsional stiffness shows the same pattern (110 → 92 units at 0.5 M vs. 118 → 105 units at 1.5 M), as does twist–stretch coupling, which changes by 0.7 units at low salt but only 0.4 units at high salt. Helical twist decreases by roughly 1.1–1.3° per kbp per 10 K at 0.5 M, with a visibly weaker dependence at 1.5 M. While both bending and torsional rigidities soften with temperature, torsional elasticity remains closer to harmonic behavior than bending, with anharmonic deviations staying below ~10% even at the highest temperatures. Structural measures, including base-pair occupancy and stacking energies, show that the duplex remains intact up to about 95 –100 °C, with only limited end fraying. Beyond quantifying these trends, the present work introduces a unified thermodynamic interpretation of DNA elasticity. The simulations demonstrate that the weakening of base-stacking interactions precedes significant hydrogen-bond disruption and acts as the primary microscopic driver of thermoelastic softening. This perspective provides a compact statistical-mechanical description of DNA thermoelasticity and helps reconcile observations from coarse-grained simulations, atomistic molecular dynamics, and single-molecule experiments.

Speaker: Isaiah Igwe (Federal University Dutsin-Ma)

13:40 → 14:00 Structural Biology: Structural basis of specific lysine transport by Pseudomonas aeruginosa permease LysP

13:40 Structural basis of specific lysine transport by Pseudomonas aeruginosa permease LysP

Under conditions of extreme acidity, the lysine-specific permease, LysP, not only mediates the import of L-lysine it also interacts with the transcriptional regulator, CadC, to activate expression of the cadAB operon. This operon encodes the lysine decarboxylase, CadA, which converts lysine to cadaverine while consuming a cytoplasmic proton, and the antiporter, CadB, which exports protonated cadaverine in exchange for extracellular lysine. Together, these processes contribute to cytoplasmic pH homeostasis and support bacterial acid resistance - a mechanism essential for the survival of pathogenic bacteria in acidic host environments. Here, we present the cryo-EM structure of LysP from Pseudomonas aeruginosa in an inward-occluded conformation (3.2–5.3 Å resolution), bound to L-lysine and a nanobody. L-Lysine is coordinated by hydrophobic contacts, cation–π interactions, and by hydrogen bonding mostly with polar uncharged residues. Reconstitution of LysP into proteoliposomes confirms specific L-lysine transport, which is competitively inhibited by L-4-thialysine. These findings provide a structural framework for understanding selective lysine recognition and inhibition, with implications for antibacterial drug design.

Speaker: Dr Emmanuel Nji (BioStruct-Africa)

14:00 → 14:30 Featured Invited Talk

14:00 From Sample to Structure: An Introduction to Cryo Electron Microscopy and Single Particle Analysis

Understanding biological function at the molecular level requires direct visualization of macromolecular structure. For decades, structural biology has relied on approaches such as X ray crystallography and nuclear magnetic resonance spectroscopy. Over the past decade, cryo electron microscopy has rapidly matured into a central method for protein structure determination, expanding the scope of questions that can be addressed at high resolution. In 2025, over 10,000 structures were deposited into the electron microscopy data bank, and in the next few years it is projected single particle cryoEM will become the predominant technique for protein structure determination.
Cryo electron microscopy enables structure determination of proteins and macromolecular complexes in a near native, vitrified state without the need for crystallization. In particular, single particle analysis has become a powerful and widely adopted method for high resolution structure determination of soluble proteins, membrane proteins, viral particles, and dynamic multicomponent assemblies. Advances in direct electron detectors, electron optics, automation, and computational image processing now make near atomic resolution structure determination increasingly routine in many academic laboratories.
The impact of cryo EM extends across diverse areas of the life sciences. In virology and infectious disease research, cryo EM has resolved the structures of viral surface proteins, intact virions, and host pathogen complexes, directly informing vaccine design and antiviral development. In therapeutic research, from small molecules to biologics and monoclonal antibodies, cryo EM enables detailed visualization of ligand binding, antigen antibody interactions, and epitope mapping, accelerating structure guided drug design. In plant biotechnology and crop science, structural insights into photosynthetic complexes, stress response machinery, and plant pathogen interactions are guiding strategies to improve yield, resilience, and food security.
At the same time, advances in in silico protein structure prediction, including AI based approaches such as AlphaFold, have transformed computational modelling. While these tools are powerful, experimental structural biology remains essential. Cryo EM provides direct structural validation, captures conformational heterogeneity, reveals ligand binding and complex formation, and enables the study of assemblies and cellular environments that remain difficult to access computationally.
This presentation will introduce the fundamental principles of cryo EM and single particle analysis, placing the method within the broader structural biology workflow. Key steps, including sample preparation, vitrification, data acquisition, and image reconstruction, will be outlined with emphasis on practical considerations. Examples from modern 200 kV cryo TEM platforms such as the Glacios microscope will illustrate how recent technological developments support a wide range of research projects.
The talk will conclude by looking beyond isolated particles toward cryo electron tomography and in situ structural analysis. These approaches enable visualization of molecular machines directly within cells, bridging molecular and cellular scales and opening new opportunities to study biology in its native context.

Speaker: Rebecca Thompson (Thermo Fisher Scientific)

14:30 → 15:00 Structural Biology

14:30 Structure-Based Discovery of KRAS Inhibitors

Abstract
Kristen rat sarcoma (KRAS) is an oncogene responsible for almost 20% of all human cancers and over 90% of pancreatic ductal adenocarcinoma. To date, only two covalent drugs are approved by the United States food and drug administration (FDA) for the treatment of KRAS G12C related cancers. However, their effectiveness is limited in cancers driven by non-G12C KRAS mutations as they rely on covalent bonding to the mutant Cys12. On top of that, the emergence of resistance to allele-specific inhibitors has shifted substantial effort toward developing noncovalent KRAS inhibitors. As a result, several noncovalent inhibitors are in clinical trials, yet none has been approved for market use, underscoring the need for new inhibitors. In this study, we reported small molecules that show a promising micromolar anti-proliferation activity against pancreatic cancer cell lines. The investigated compounds are mainly amine-containing heterocycles with scaffolds that are distinct from those found in existing drugs or lead molecules.The molecules were identified through a structure-based drug design campaign on a physicochemically tailored 3D ligand library against switch II pocket of KRAS mutants. Based on their micromolar activity, extensive interactions in predicted binding modes, and analyses of structural and physicochemical features, we propose that these active hits can serve as a starting point for the future characterization and optimization of pan-KRAS inhibitors with broad efficacy. Moreover, our work demonstrates the proof of concept for using virtual screening in noncovalent drug discovery to benefit from abundant 3D structures of drug-like molecules and the growing database of experimental protein structures, especially when computational resources are limited.

Keywords: KRAS drug discovery, virtual screening, molecular docking, cell growth assay

• Correspondence to: amanuel.getahun@bdu.edu.et

Speaker: Mr Amanuel Getahun Addis (Bahir Dar University)

15:00 → 15:40 Featured Invited Talk

15:00 Multiscale local self-organization of the human metaphase mitotic spindle

The current model of mitotic spindle assembly proposes that microtubules nucleate at spindle poles and grow inward to capture chromosomes. However, recent structural studies reveal that spindles are composed of short microtubules that do not span the full pole-to-chromosome distance. It remains unclear how short, disconnected microtubules collectively generate and transmit the forces necessary to build a bipolar spindle. Using cryo-electron tomography to map microtubule polarity in intact human cells, we find that spindle microtubules form locally antiparallel dense regions with a consistent 8 nm wall-to-wall spacing. This spacing is too narrow for most molecular motors to fit between adjacent microtubules, ruling out direct motor crosslinking of the bundle interior. Instead, spacing scales inversely with local microtubule density, consistent with density-driven steric interactions, analogous to liquid crystal ordering. Motor perturbations combined with centriole depletion, which generated motor-active monopolar spindles, further revealed that the kinesin-5 Eg5 motor establishes local antiparallel overlap independently of spindle bipolarity, while a balance of Eg5 and dynein regulates microtubule density to maintain spindle architecture. Together, these findings challenge the pole-centric model and suggest a bottom-up, self-organized model in which motor-microtubule interactions within dense bundles generate forces that build bipolar spindles.

Speaker: Dr Will Conway (New York Structural Biology Consortium)