Biophotonics at the nanoscale: Measuring forces, fluctuations, and function in cells

Inside every cell, function emerges from a dense, dynamic network of molecular interactions. Molecules bind, unbind, and reorganize in a noisy, out-of-equilibrium environment – yet reliably produce coordinated responses. The question is: what are the physical rules governing this behavior? The challenge has been measurement. Intermolecular forces, binding kinetics, and stochastic fluctuations all occur at nanometer scales and microsecond timescales - regimes that are notoriously difficult to access experimentally. In this talk, I’ll present multiparametric super-resolution imaging approaches that resolve these dynamics directly, quantifying spatial correlations, interaction potentials, and non-equilibrium behavior at the single-molecule level¹. I’ll then show how engineered probes - specifically superparamagnetic nanoparticles² - can be used to apply controlled forces and perturbations, effectively turning passive observation into active interrogation of subcellular organization³. Finally, I’ll connect these measurements to minimal model systems: synthetic membranes with tunable interactions. These systems allow us to describe molecular clustering and phase separation within a thermodynamic and statistical physics framework^4,5, providing insight into how cells organize signaling platforms under non-equilibrium conditions.
[1] N. Bartels et al. Science Advances 10, eadn3238 (2024)[2] A. Neusch, et al. Nano Letters 25, 18006-15 (2025)[3] D. Lisse, et al. Advanced Materials 29, 1700189 (2017)[4] C. Monzel, et al. Nature Communications 6, 8162 (2015)[5] JA Janeš et al. Physical Review X 12, 031030 (2022)