Dual-functional aggregation-induced emission active chitosan-based hydrogel for the detection and killing of pathogenic bacteria

Current strategies for treating bacterial infections primarily rely on antibiotics, with only limited follow-up monitoring to verify that all bacteria have been eradicated. This limitation has driven research toward the development of advanced biomaterials with dual capabilities of antibacterial activity and bacterial detection. Functionalized hydrogels, with their architecturally dynamic and stimulus-responsive frameworks, have emerged as fundamental materials in biomedicine and adaptive sensing. Herein, we report a cost-effective, one-step synthesis of an Aggregation-Induced Emission (AIE)-active hydrogel through the covalent functionalization of chitosan (Ch) with 1-pyrenecarboxaldehyde (1-PCA), forming an injectable, self-healing biomaterial (ChPCA) with inherent luminescent properties through a heat-to-cool transition. The simplicity and affordability of this technique make it highly promising for future scalability and practical applications in advanced material development. Beyond structural characterization using FTIR, PXRD, TGA, FESEM, and contact angle analyses, density functional theory (DFT) calculations elucidate critical parameters for gel stability. Furthermore, the hydrogel shows potent antibacterial activity against <i>S. aureus</i> (Gram-positive) and <i>E. coli</i> (Gram-negative) bacterial strains without requiring additional antibiotics. This activity is attributed to its membrane-targeting mechanism, which is further confirmed through SEM analysis. The inherent AIE effect facilitates real-time bacterial detection, with preferential accumulation on microbial membranes leading to cell membrane disruption and intracellular penetration. This study introduces a versatile, antibiotic-free strategy for fighting against pathogenic bacterial strains, and it also provides a scalable framework for developing next-generation biomaterials with significant potential in both bacterial detection and therapeutic applications.