Absorption-dependent generation of singlet oxygen from gold bipyramids excited under low power density
Abstract
Metal nanoparticles (MNPs) can be used as a kind of new photodynamic therapy (PDT) agent because singlet oxygen (1O2) can be generated through directly sensitizing MNPs. Gold nanorods, gold nanoshells and gold nanoechinus were confirmed to be efficient PDT agents in vivo. However, the major excitation spectra of 1O2 from all of them are not in the optical biological window (650–900 nm). Herein, gold bipyramids (GBPs) with tunable absorption wavelength were prepared and used to explore 1O2 generation capability. 1O2 can be generated when GBPs were excited by continuous-wave light within a wide range of wavelengths (660–975 nm). The highest 1O2 generation capabilities were obtained when they were excited at the wavelength of the absorption peak, which was quite different from those of other gold nanomaterials. It was also found that 1O2 can be generated efficiently by a laser of very low power density (200 mW cm−2). The capability of GBPs for PDT has been demonstrated through the destruction of cancer cells. The synergistic effect of PDT and photothermal therapy for the destruction of cancer cells was also demonstrated.
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