Dual antibacterial activities of a chitosan-modified upconversion photodynamic therapy system against drug-resistant bacteria in deep tissue

Photodynamic therapy (PDT) has recently been proposed as an innovative approach to combat multi-drug resistant (MDR) bacteria. To improve the penetration depth of current PDT, a core–shell upconversion nanoparticle (UCNP) based PDT system, composed of a cationic N-octyl chitosan (OC) coated UCNP loaded with the photosensitizer zinc phthalocyanine (OC-UCNP-ZnPc), was constructed to enhance the antibacterial efficacy against MDR bacteria in deep...