The in-situ synthesis of porous halamine nanodots inside a bacterial cellulose nanofibrous hydrogel with robust chlorine rechargeable biocidal function

Microbial proliferation is the major obstacle that shortens the vase life of fresh-cut flowers. Conventional strategies in prolonging the vase time of fresh-cut flowers are limited due to the irreversible depletion of the directly added antimicrobial agents. Herein, we report a scalable approach to modify the bacterial cellulose (BC) nanofibrous hydrogels with chlorine rechargeable biocidal function against a broad spectrum of microorganisms. Porous halamine nanodots (PHNs), which were synthesized based on a condensation polymerization reaction between melamine and cyanuric chloride, were covalently bonded to the BC nanofibers via an in-situ growth process. The modified BC nanofibrous hydrogel exhibited integrated properties of high water capacity and recovery ratio, acceptable mechanical performance, and good thermal stability. Moreover, the chlorinated PHN@BC, with a high active chlorine capacity (> 400 ppm), desirable chlorine rechargeability, and good long-term durability, demonstrated a promising biocidal efficiency against typical bacteria and fungi, achieving 6 log CFU reduction of bacteria ( E. coli and P. aeruginosa ) and fungus ( C. tropicalis ) within 5 min of contact even under a high chemical oxygen demand condition. Besides, the application of chlorinated PHN@BC hydrogels in the vase solution was demonstrated to prolong the vase life of fresh-cut roses from 5.89 to 7.67 days, exhibiting a comparable efficacy with currently developed preservation strategies. Graphical abstract