Gold nanorods-conjugated TiO(2) nanoclusters for the synergistic combination of phototherapeutic treatments of cancer cells

BACKGROUND: Recently, a combination of photodynamic therapy (PDT) and photothermal therapy (PTT) to generate reactive oxygen species (ROS) and heat to kill cancer cells, respectively has attracted considerable attention because it gives synergistic effects on the cancer treatment by utilizing the radiation of nontoxic low-energy photons such as long wavelength visible light and near IR (NIR) penetrating into subcutaneous region. For the effective combination of the phototherapies, various organic photosensitizer-conjugated gold nanocomplexes have been developed, but they have still some disadvantages due to photobleaching and unnecessary energy transfer of the organic photosensitizers. RESULTS: In this study, we fabricated novel inorganic phototherapeutic nanocomplexes (Au NR–TiO(2) NCs) by conjugating gold nanorods (Au NRs) with defective TiO(2) nanoparticle clusters (d-TiO(2) NP clusters) and characterized their optical and photothermal properties. They were observed to absorb a broad range of visible light and near IR (NIR) from 500 to 1000 nm, exhibiting the generation of ROS as well as the photothermal effect for the simultaneous application of PDT and PTT. The resultant combination of PDT and PTT treatments of HeLa cells incubated with the nanocomplexes caused a synergistic increase in the cell death compared to the single treatment. CONCLUSION: The higher efficacy of cell death by the combination of PDT and PTT treatments with the nanocomplexes is likely attributed to the increases of ROS generation from the TiO(2) NCs with the aid of local surface plasma resonance (LSPR)-induced hot electrons and heat generation from Au NRs, suggesting that Au NR–TiO(2) NCs are promising nanomaterials for the in vivo combinatorial phototherapy of cancer. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s12951-018-0432-4) contains supplementary material, which is available to authorized users.