Broad-wavelength light-driven high-speed hybrid crystal actuators actuated inside tissue-like phantoms

Abstract

Research on molecular crystals exhibiting light-driven actuation has made remarkable progress through the development of various molecules and the identification of driving mechanisms. However, crystals developed to date have been driven mainly by ultraviolet (UV) or blue light irradiation, and driving by red or near-infrared (NIR) light has not been attempted yet. Herein, a broad-wavelength light-driven molecular crystals that exhibit high-speed bending by photothermal effect is developed. Titanium carbide (Ti3C2Tx) MXene nanosheets are integrated into salicylideneaniline crystals to extend the wavelength range that causes photothermally driven bending to UV, visible, and NIR light. In addition, unlike the thin pristine molecular crystals that show slow photoisomerization-induced bending only under UV light, the MXene layer enables the molecular crystals to be actuated rapidly regardless of their thickness over a wide range of wavelengths. The hybridization of molecular crystals with MXene, which exhibits strong biocompatibility as well as NIR light-driven photothermal effect, allows for the bending of the hybrid crystals inside agar phantoms mimicking biological tissue. Last, it is confirmed that MXene hybridization can be extended to common molecular crystals including various salicylideneaniline and anisole derivatives.