Noninvasive and Reversible Cell Adhesion and Detachment via Single-Wavelength Near-Infrared Laser Mediated Photoisomerization.

Dynamically regulating cell-molecule interactions is fundamental to a variety of biological and biomedical applications. Herein, for the first time, by utilizing spiropyran conjugated multishell upconversion nanoparticles (UCNPs) as a new generation of single-wavelength near-infrared (NIR)-controlled photoswitch, we report a simple yet versatile strategy for controlling cell adhesion/detachment reversibly and noninvasively. Specifically, the two-way isomerization of the photoswitch was merely dependent on the excitation power density of the 980 nm laser. At high power density, the ring-opening was prominent, whereas its reverse ring-closing process occurred upon irradiation by the same laser but with the lower power density. Such transformations made the interactions between spiropyran and cell surface protein fibronectin switchable, thus leading to reversible cell adhesion and detachment. Moreover, efficient adhesion-and-detachment of cells could be realized even after 10 cycles. Most importantly, the utilization of NIR not only showed little damage toward cells, but also improved penetration depth. Our work showed promising potential for in vivo dynamically manipulating cell-molecule interactions and biological process.