Rational design of silver NPs-incorporated quaternized chitin nanomicelle with combinational antibacterial capability for infected wound healing

Bacterial and biofilm infections are prevalent, photothermal antibacterial therapy exploiting Ag NPs was an alternative. However, various matrix materials including polysaccharides used to stabilize Ag NPs are not efficiently utilized. In this study, catechol functionalized quaternized chitin (DQC) is first synthesized, then Ag+ is in situ reduced to small Ag NPs stabilized and well-dispersed by DQC to form Ag NPs-incorporated quaternized chitin (DQCA) nanomicelle in a green and simple way. The photothermal conversion efficiency of the DQCA was up to be 65 %, which was much higher than that of many reported systems. The rationally designed DQCA takes full advantage of each component, specifically, DQCA is endowed with bacterial targeting, sterilization effects of cationic groups and Ag NPs, and superior photothermal combinational bactericidal and antibiofilm activities. The in vitro antibacterial rate of DQCA with NIR laser irradiation was >95 % in 10 min (99.5 % for E. coli and 95.7 % for S. aureus, respectively), and the eradication efficiency against both of the E. coli and S. aureus biofilms reached up to 99.9 %. Moreover, full-thickness S. aureus biofilms-infected wound healing test in the mouse model demonstrates that the combinational effect of DQCA nanomicelle could significantly accelerate the wound healing, by simultaneously reducing inflammation, enhancing re-epithelialization and promoting collagen deposition. And the wound treated with DQCA plus NIR irradiation at day 15 possessed the smallest open wound (2.5 %). Collectively, these features indicate facilely fabricated DQCA nanomicelle gets the most use of each component, and could serve as an excellent alternative for bacterial infection therapy.