BPS2026 – Deciphering cell states using quantum limited label-free light interference energetics (LIFE)

All current assays for cell viability and/or health, such as LIVE/DEAD staining, electrophoresis for genomic DNA, etc., are destructive, which prohibits longitudinal monitoring of samples. To overcome this challenge, we developed a non-destructive optical measurement platform to quantify cellular health states. Based on principles of homodyne detection, we developed the light interference energetics (LIFE) scope. Illuminated by a low-noise laser limited only by shot noise, one part of the incident light is scattered by subcellular components. This scattered light then forms interference patterns with the other part of incident light reflected by the substrate beneath the sample. The low-noise characteristic of the laser ensures that interference patterns are directly related to optical properties of subcellular structures. Temporal changes of interference patterns signify the dynamic nature of subcellular components. Previously, we demonstrated that LIFE scope can distinguish healthy, dying, and dead cells based off dynamic interference patterns. However, it is unclear how dynamics of different subcellular structures, such as cytoskeletons and biomolecular condensates (BMCs) map to dynamic interference patterns. To gain understanding, we acquired LIFE images of cells and BMCs for 30 seconds with 200-Hz sampling rate, followed by analysis in Fourier domain. Perturbation of the myosin II doubled the power-spectral decay relative to controls, suggesting enhanced diffusion of small intracellular components upon actomyosin contractility disruption. In parallel, in vitro BMCs consisting of poly-l-lysine and ATP exhibited distinct frequency peaks at interfaces versus interiors, with up to 17% higher spectral power (88–89.5 Hz) compared to buffer controls. These results demonstrate that LIFE scope can detect dynamic signatures of cytoskeletal organization and heterogeneity of biomolecular condensates in a label-free and nondestructive way and may be useful for longitudinal cell biology studies of the same sample.