Methylene blue-loaded gold nanobipyramids @SiO2 enhanced singlet oxygen generation for phototherapy of cancer cells

Plasmonic nanoparticles hold great potential in photodynamic therapy (PDT). Herein, a nanoplatform of methylene blue (MB) loaded gold nanobipyramids@SiO2 (GBPs@SiO2-MB) was designed to optimize the generation rate of singlet oxygen (1O2), which was based on the plasmonic effect. The surface plasmon resonance (SPR) of GBPs was finely overlapped with the excitation absorption of MB, a wildly applied organic PDT drug prone to enzymatic degradation. This mesoporous silica coating nanoplatform protects MB molecules against degradation, and this overlap greatly enhances the 1O2 yield of MB by the SPR electron from the GBPs. The GBPs@SiO2-MB nanoparticles exhibit a synergistic effect of PDT and photothermal therapies (PTT) of cancer cells under laser irradiation. This study provides a alternative strategy to improve the classic MB treatment for phototherapy application.