High-efficiency photothermal sterilization on PDMS film with Au@CuS yolk-shell nanoparticles

Since the global COVID-19 pandemic, the development of biocide-free antibacterial surfaces based on other sterilization mechanisms has gathered momentum. It however faces significant challenges. Photothermal sterilization based on photothermal agents (PTA), which can convert light energy to heat under near-infrared (NIR) irradiation, has been proposed as an attractive method to prevent bacterial infections and contamination. Gold nanoparticles (AuNPs) with localized surface plasmon resonance, which cause a photothermal effect via high photothermal conversion from light to heat energy, are generally used as PTA, and CuS as a p-type semiconductor with a narrow band gap is an emerging PTA. Therefore, in this study, an Au@CuS yolk-shell with inner gaps was prepared via the Kirkendall effect, and its photothermal performance was tested under NIR irradiation. Polydimethylsiloxane (PDMS) was used as the supporting substrate with low surface energy. Photothermal sterilization effect was explored by inactivating E. coli using Au@CuS/PDMS films. Effective inactivation of E. coli was observed in the 0.025 wt% Au@CuS/PDMS film within 10 s of NIR irradiation. The results show that the dramatic inactivation of E. coli is caused by the photothermal effect generated by the coupling of CuS and AuNPs.