Single-Cell Biophysics: Measurement, Modulation, and Modeling

Single-Cell Biophysics: Measurement, Modulation, and Modeling

Poster Abstracts

58-POS Board 29 Manipulation of Receptor Tension in Living Cells by Nanoscale Optomechanical Actuators Zheng Liu 1,2 , Yang Liu 2 , Khalid Salaita 2 . 1 Wuhan University, Wuhan, Hubei, China, 2 Emory University, Atlanta, GA, USA. Mechanical force has a critical role in many cellular functions, including cell division, gene expression, differentiation and motility. Despite its fundamental importance to cell biology, significant gaps remain in our understanding of the coupling between chemical and mechanical signals. As a first step to understanding mechanotransduction circuits operating within cells, a number of techniques have been developed to investigate the response of individual cells to spatially confined physical perturbations. The current state-of-the-art tools for force manipulation of living cells, such as the atomic force microscope and optical and magnetic tweezers have been hampered by their low experimental throughput. Another general approach involves using magnetic actuation of nanoparticles and micropillars are lack of spatial and tempo resolution in mechanical stimulation and molecular specificity. To address these challenges, we developed an approach involving optomechanical actuator (OMA) nanoparticles that are controlled with near-infrared light. Illumination leads to OMA particle collapse, delivering piconewton forces to specic cell surface receptors with high spatial and temporal resolution. OMA nanoparticles were comprised of a plasmonic gold nanorod core coated with a thermo-responsive polymer shell (poly(N-isopropylmethacrylamide, pNIPMAm) . With this design, the gold rod functions as a photothermal transducer, converting NIR excitation to localized heat that drives a drastic and transient collapse of the polymer shell. OMA nanoparticles rapidly shrink upon photo-illumination, and exclusively apply forces to cell receptors that are bound to their cognate ligands on the nanoparticle surface. The amplitude, duration, repetition and loading rate of the mechanical input are controlled by the NIR illumination profile. We demonstrate optomechanical actuation by controlling integrin-based focal adhesion formation, cell protrusion and migration, and t cell receptor activation.

127