Near-infrared (NIR) controlled reversible cell adhesion on a responsive nano-biointerface

Light-activated dynamic variations have promoted the development of smart interfaces, especially nano-biointerfaces. In this article, the near-infrared (NIR)- responsive surface for controlling cell adhesion was designed by grafting a thermal responsive polymer (poly(N-isopropylacrylamide), PNIPAM) onto silicon nanowires (SiNWs) instead of the traditional photosensitive moieties. NIR induced the photothermal effect of the SiNWs, and the local heat induced thermodynamic phase transformation of PNIPAM. With the application of NIR radiation, the surface turned to a hydrophobic state, and restored to the hydrophilic state when NIR was switched off, leading to reversible cell adhesion and release. The switchable wettability of the surface and cell adhesion/release occurred efficiently even after 20 cycles. Proteins were anchored on the surface via hydrophobic interactions using NIR; further connection of a cell-capture agent helped in achieving specific cell capture. This dynamic control of cell adhesion via NIR may provide new clues for designing functional nano-biointerfaces.