Yolk-structured multifunctional up-conversion nanoparticles for synergistic photodynamic–sonodynamic antibacterial resistance therapy

layer, which improved the biocompatibility of the UCNPs, surrounded the yolk structure, with a cavity space which had a high efficiency of loading photosensitizers. Synergistic PDT and sonodynamic therapy (SDT) improved the photosensitizer utilization rate. As a result, a greater inhibition rate was observed when antibiotic-resistant bacteria were treated with a combined therapy (100%) compared with either the PDT (74.2%) or SDT (70%) alone. Our data indicate that the multifunctional NPs developed in this study have the potential for use in the clinical synergistic PDT-SDT treatment of infectious diseases caused by antibiotic-resistant bacteria.