Mutual boost between free radicals and photothermal effect for synergistic photothermal/thermodynamic antibacterial...

Combined treatment is a promising strategy in antibacterial treatment, which could alleviate the shortcomings of monotherapy and achieve better therapeutic effects. In this work, mutual boost between free radical generation and photothermal effect for synergistic photothermal/thermodynamic antibacterial therapy was reported. Mesoporous silica nanoparticles were used as drug carrier for loading dibenzoyl peroxide (BPO). The pores of mesoporous silica nanoparticles were blocked by GSH-responsive polyethylenimine (PEI) layer. 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) was then adsorbed via electrostatic force to prepare the nanosystem. At the site of bacterial infection, the BPO was released and decomposed to aryl radicals. The aryl radicals oxidized ABTS to photothermal reagent of ABTS^·+, which produced photothermal effect to enhance the antibacterial effect under 808 nm laser irradiation. Moreover, the photothermal effect accelerated the decomposition of BPO to boost the levels of free radicals as a return, further improved the antibacterial efficiency. The in vitro experiments indicated that the photothermal/thermodynamic therapeutic nanosystem have a synergistic antibacterial effect efficiency (˃95 %) for both E. coli and S. aureus, as well as biofilm disruption and inhibition. This mutual boost between free radical ion generation and photothermal effect provides a new and feasible strategy for the synergistic antibacterial therapy.