Nanocomposites Containing Silica-Coated Gold–Silver Nanocages and Yb–2,4-Dimethoxyhematoporphyrin: Multifunctional Capability of IR-Luminescence Detection, Photosensitization, and Photothermolysis

Abstract

We describe novel composite nanoparticles consisting of a gold–silver nanocage core and a mesoporous silica shell functionalized with the photodynamic sensitizer Yb–2,4-dimethoxyhematoporphyrin (Yb–HP). In addition to the long-wavelength plasmon resonance near 750–800 nm, the composite particles exhibited a 400-nm absorbance peak and two fluorescence peaks, near 580 and 630 nm, corresponding to bound Yb–HP. The fabricated nanocomposites generated singlet oxygen under 630-nm excitation and produced heat under laser irradiation at the plasmon resonance wavelength (750–800 nm). In particular, we observed enhanced killing of HeLa cells incubated with nanocomposites and irradiated by 630-nm light. Furthermore, an additional advantage of fabricated conjugates was an IR-luminescence band (900–1060 nm), originating from Yb3+ ions of bound Yb–HP and located in the long-wavelength part of the tissue transparency window. This modality was used to control the accumulation and biodistribution of composite particles in mice bearing Ehrlich carcinoma tumors in a comparative study with intravenously injected free Yb–HP molecules. Thus, these multifunctional nanocomposites seem an attractive theranostic platform for simultaneous IR-luminescence diagnostic and photodynamic therapy owing to Yb–HP and for plasmonic photothermal therapy owing to Au–Ag nanocages