Force-Triggered Self-Destructive Hydrogels

DNA hydrogels and their derivatives in biomedical engineering applications

Deoxyribonucleotide (DNA) is uniquely programmable and biocompatible, and exhibits unique appeal as a biomaterial as it can be precisely designed and programmed to construct arbitrary shapes. DNA hydrogels are polymer networks comprising cross-linked DNA strands. As DNA hydrogels present programmability, biocompatibility, and stimulus responsiveness, they are extensively explored in the field of biomedicine. In this study, we provide an overview of recent advancements in DNA hydrogel technology. We outline the different design philosophies and methods of DNA hydrogel preparation, discuss its special physicochemical characteristics, and highlight the various uses of DNA hydrogels in biomedical domains, such as drug delivery, biosensing, tissue engineering, and cell culture. Finally, we discuss the current difficulties facing DNA hydrogels and their potential future development.

Self-regulated reversal deformation and locomotion of structurally homogenous hydrogels subjected to constant light illumination

Environmentally adaptive hydrogels that are capable of reconfiguration in response to external stimuli have shown great potential toward bioinspired actuation and soft robotics. Previous efforts have focused mainly on either the sophisticated design of heterogeneously structured hydrogels or the complex manipulation of external stimuli, and achieving self-regulated reversal shape deformation in homogenous hydrogels under a constant stimulus has been challenging. Here, we report the molecular design of structurally homogenous hydrogels containing simultaneously two spiropyrans that exhibit self-regulated transient deformation reversal when subjected to constant illumination. The deformation reversal mechanism originates from the molecular sequential descending-ascending charge variation of two coexisting spiropyrans upon irradiation, resulting in a macroscale volumetric contraction-expansion of the hydrogels. Hydrogel film actuators were developed to display complex temporary bidirectional shape transformations and self-regulated reversal rolling under constant illumination. Our work represents an innovative strategy for programming complex shape transformations of homogeneous hydrogels using a single constant stimulus.