Composite of silver nanoparticles and photosensitizer leads to mutual enhancement of antimicrobial efficacy and promotes wound healing

Antimicrobial photodynamic therapy (aPDT) is a new therapeutical modality highly advocated recently to meet the challenge of drug resistant bacteria. In this study, we developed a composite material to combine silver nanoparticle, a commonly used disinfectant, with a potent photosensitizer for aPDT. Interestingly, we found the photosensitizer activated the silver nanoparticles into silver ions under light illumination. At the same time, silver nanoparticles enhanced the generation of ROS by the photosensitizer. Together, the two components activates each other, leading to remarkable antimicrobial efficacy against not only gram-positive and -negative bacteria, but also drug resistant bacteria (Methicillin Resistant S. aureus, MRSA). Such antimicrobial effect was further demonstrated on a bacterial infection model on mice. We showed that the chemical treatment, the high temperature or the pressure during the preparation did not affect the cellulosic structures of the fabric based on the characterization of optical, mechanical and thermal properties of the composite material. aPDT is typically a localized therapy, depending on the contact of bacteria to the photosensitizers, while the silver nanoparticles released the silver ions into the solution and can kill the bacteria thereof. Thus, our current study demonstrates the complementarity of aPDT and silver nanoparticles and mutual promotion of antibacterial effects to even drug-resistant bacteria.