Near-Infrared-Triggered Multi-Enhanced Photodynamic/Immuno Therapy with Yolk-Shell Hybrid Plasmonic Nanostructures for Multidrug-Resistant Bacterial Infection

Photodynamic therapy (PDT) and immunotherapy are two promising weapons against systemic multidrug-resistant (MDR) bacterial infection. However, low productivity of reactive oxygen species (ROS) and genetic diversity of germs hinder the generation of enough antigens from combating the problem. Here, we creatively synthesized plasmonic Au@CdSe x S 1-x yolk-shell nanostructrues with Ag doping (ACSS Y-S), which triggers the enhanced PDT and immunotherapy under NIR light. The Au nanorods (NRs) utilize the NIR laser to generate hot-electrons which can be injected into the CdSe x S 1-x shell, providing the basis for the production of ROS. Furthermore, enhanced PDT is realized by following ingenuities: 1) multiple reflection and scattering of incident light in yolk-shell microcavity, 2) the optimal band gap alignment by controllable CSS composition which achieves highly efficient hot-electrons injection, and 3) the introduction of Ag doping with optimal concentration in CSS shell that prevents the combination of electrons and holes. As a result, comparably, more than 30-fold superoxide radicals (·O 2 -) and hydroxyl radicals (·OH) are produced. And the MIC value of the ACSS Y-S is lower than 1/64 of traditional core−shell structure. Notably, Selenium (Se) as immune adjuvant in ACSS Y-S boosts immune response after PDT, leading to the successful treatment of systemic MDR bacterial infection.