Thermal-responsive gated nanocomposite of antibacterial gold nanoclusters

Abstract

A thermal-responsive antibacterial nanocomposite was developed based on the photodynamic gold nanoclusters (AuNCs). N-cetyltrimethylammonium bromide was applied as a soft template to prepare silica nanoparticles (sSiO2@CTAB-SiO2). After etching, the hollow mesoporous silica nanoparticles (HMSN) were prepared and subsequently surface-grafted with thermal-responsive poly(N-isopropylacrylamide) to construct nanocomposites, named HMSN-PNIPAM. The ultrasmall-sized AuNCs matched well with the pore size of HSMN. The poly(N-isopropylacrylamide) underwent a reversible phase transition at varied temperature, which accompanied the change of apparent volume. It could realize the open/closed switch of HMSN pores for AuNCs loading in and sealed up effectively, thus constructing the AuNCs-loaded nanocomposites, termed as HMSN-AuNC. Under mild heating and light irradiation, the AuNCs in HMSN-AuNC could be released and generate reactive oxygen species, which could then perform the bacteria killing. Therefore, taking advantages of the thermo-responsiveness of poly(N-isopropylacrylamide) and the photodynamic property of AuNCs, the nanocomposite exhibited a "switching" effect on both temperature and light, and its antibacterial performance could be realized in a controlled manner.