Extreme transport of light in spheroids of tumor cells in Nature communications

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ISC researchers Davide Pierangeli and Valentina Pamieri coauthored an interesting reasearch article published in Nature Communications.

“Extreme transport of light in spheroids of tumor cells”

Giordano Perini, Valentina Palmieri, Ivana Grecco, Ginevra Friggeri, Marco De Spirito, Massimiliano Papi, Eugenio Del Re  and Claudio Conti,

Nature Communications  14, 4662 (2023)

Abstract

Extreme waves are intense and unexpected wavepackets ubiquitous in complex systems. In optics, these rogue waves are promising as robust and noise-resistant beams for probing and manipulating the underlying material. Localizing large optical power is crucial especially in biomedical systems, where, however, extremely intense beams have not yet been observed. We here discover that tumor-cell spheroids manifest optical rogue waves when illuminated by randomly modulated laser beams. The intensity of light transmitted through bio-printed three-dimensional tumor models follows a signature Weibull statistical distribution, where extreme events correspond to spatially-localized optical modes propagating within the cell network. Experiments varying the input beam power and size indicate that the rogue waves have a nonlinear origin. We show that these nonlinear optical filaments form high-transmission channels with enhanced transmission. They deliver large optical power through the tumor spheroid, and can be exploited to achieve a local temperature increase controlled by the input wave shape. Our findings shed light on optical propagation in biological aggregates and demonstrate how nonlinear extreme event formation allows light concentration in deep tissues, paving the way to using rogue waves in biomedical applications, such as light-activated therapies.

a Sketch of multiple light scattering through a spheroid of tumor cells. The laser beam (λ = 532 nm) is phase-modulated by a spatial light modulator (SLM) and the optical intensity in the transmission plane (dashed area) is detected by a camera. b Bright-field microscopy image of a three-dimensional tumor model (3DTM) bioprinted from human pancreatic cells. The false-color image highlights high-density regions. Scale bar is 500 μm. Speckle patterns showing the spatial intensity transmitted through the millimetric volume sample c at 5 mW input power (normal waves, NWs) and d in the presence of a rogue wave (RW) at 20 mW. Scale bar is 50 μm.