Cu2−xSe nanoparticles for efficient antibacterial photothermal therapy in the second near-infrared window

Bacterial infections pose a severe and growing threat to public health and the global economy, exacerbated by the rise of drug-resistant pathogens. This urgent challenge demands the development of non-antibiotic strategies with robust antibacterial activity. Nanotechnology-driven photothermal therapy (PTT) facilitated by near-infrared (NIR) light has emerged as a promising alternative. However, conventional PTT using 808 nm light (NIR-I window) suffers from limitations such as limited tissue penetration and potential collateral cell damage due to non-specific heating. To overcome these limitations, we have developed bovine serum albumin (BSA)-stabilized Cu ₂₋ₓ Se nanoparticles (NPs), which exhibit strong NIR-II absorption (1064 nm) enabling deeper tissue penetration and reduced off-target effects. Under 1064 nm irradiation, Cu ₂₋ₓ Se NPs achieve bactericidal temperatures of 53.6 °C and 57.2 °C at low power densities (0.5 and 1 W cm⁻², respectively), while BSA coating supports colloidal stability and biocompatibility. These NPs demonstrate > 99% antibacterial activity against drug-resistant pathogens, outperforming conventional NIR-I agents in both efficacy and safety.