A photo-triggered hydrogel for bidirectional regulation with imaging visualization†
The bidirectional intelligent regulation of hydrogels is a critical challenge in on-demand functional hydrogels. In this paper, a photo-triggered hydrogel for bidirectional regulation based on IR820–α-cyclodextrin/polyethylene glycol methyl acrylate was developed. This thermosensitive hydrogel can soften from gel to sol under near-infrared irradiation based on the photothermal effect of IR820, while the hydrogel can stiffen based on the photo-crosslinking of polyethylene glycol methyl acrylate under UV laser irradiation. After implanting in vivo, the softness and stiffness of the hydrogel can be regulated in a bidirectional manner by the switching of the irradiation wavelength. Moreover, the location and status of the hydrogel was tracked in vivo by fluorescence imaging due to the fluorescence labeling of IR820. The controlled and visible hydrogel could be potentially applied to different biomedical fields for precise treatment.