In Situ Ultrafast Construction of Polysaccharide-Based Janus Hydrogel Films by Asymmetric Cross-Linking for On-Demand Sterilization

Abstract

Excessive and repetitive use of disinfectants poses a significant waste and health hazard; therefore, developing a more secure and efficient sterilization strategy is of great significance in safeguarding public health. Herein, we propose a facile strategy for rapidly fabricating a carboxymethyl chitosan (CMCS)/sliver nanoparticle (AgNPs)/Zn 2+ Janus hydrogel film (CAZ) through in situ asymmetric cross-linking for on-demand sterilization. The Zn 2+ diffusion from the surface toward the interior rapidly constructed the Janus hydrogel structure with a high cross-linking front and a low cross-linking back, realizing ultrafast film formation in approximately 3 s. Ingeniously, the Janus structure confers asymmetric adhesion (167 times difference) to CAZ and forms an antiadhesion front that can be touched by hand and an adhesion back that firmly adheres to the target surface, achieving the positioning and self-matching film formation. Specifically, the antibacterial activity was significantly enhanced by introducing a small amount of AgNPs (0.08 wt %). The three-dimensional movement trajectory of bacteria gradually weakened (10 min) and disappeared (30 min) on CAZ, demonstrating the excellent contact bactericidal performance. Moreover, the CAZ had great biocompatibility, ensuring biosafety. Consequently, in situ preparation of CAZ on the sensitive area surfaces could achieve fast and long-term on-demand sterilization, providing a green and safe strategy for public health protection.