Department of Chemistry and Bioscience, Graduate School of Science and Engineering, Kagoshima University, 1-21-35 Korimoto, Kagoshima 890-0065, Japan.
Phys Chem Chem Phys. 2011 Dec 21;13(47):21026-34. doi: 10.1039/c1cp22683e. Epub 2011 Oct 20.
The photocatalytic and plasmonic photothermal cancer cell-killing activity of the metallic Au-capped TiO(2) (Au@TiO(2)) composite colloidal nanopellets has been investigated on HeLa cells under UV-visible (350-600 nm) light irradiation. The Au@TiO(2) composite nanopellets with the uniform Au-capped TiO(2) structure were successfully synthesized by simple reduction of HAuCl(4) on the surface of TiO(2) nanoparticles. The morphological structure and surface properties of Au@TiO(2) were characterized by using UV-visible absorption spectroscopy, TEM, SEM, XPS, EDX and XRD analyses. The formation of hydroxyl radicals (˙OH) was confirmed by photoluminescence (PL) spectra. The photocatalytic and photothermal cell-killing activity of the Au@TiO(2) nanopellets was found to vary with the molar ratio of Au to TiO(2). The direct involvement of the metal particles in mediating the electron transfer from the photoexcited TiO(2) under the band gap excitation is considered to carry out the efficient photocatalytic reaction on the cells. The plasmonic absorption spectra of Au@TiO(2) suspensions were also measured for the evaluation of photothermal cell killing. The charge separation, the interfacial charge-transfer and photothermal activity promoted the photocatalytic-photothermal cancer-cell killing more than TiO(2) alone. The cytotoxic effect of Au@TiO(2) nanopellets with low concentration of gold (TiO(2) : Au molar ratio > 1 : 1) was found to be 100%, whereas that of the commercial TiO(2) (P25) was ca. 50%. The comparative study of the cell viability using Au alone and TiO(2) alone revealed that the synergistic effect of photocatalytic hydroxyl radical formation and Au-plasmonic photothermal heat generation plays a vital role in the cancer cell killing. A plausible mechanism was also proposed for photocatalytic cancer cell killing based on the obtained results.
已经研究了在紫外可见（350-600nm）光照射下，金属 Au 封端的 TiO(2)（Au@TiO(2)）复合胶体纳米颗粒的光催化和等离子体光热杀癌细胞活性。通过简单地将 HAuCl(4)还原在 TiO(2)纳米颗粒的表面上，成功地合成了具有均匀的 Au 封端 TiO(2)结构的 Au@TiO(2)复合纳米颗粒。使用紫外可见吸收光谱、TEM、SEM、XPS、EDX 和 XRD 分析对 Au@TiO(2)的形态结构和表面性质进行了表征。通过光致发光（PL）光谱证实了羟基自由基（˙OH）的形成。发现 Au@TiO(2)纳米颗粒的光催化和光热细胞杀伤活性随 Au 与 TiO(2)的摩尔比而变化。金属颗粒直接参与介导带隙激发下光激发 TiO(2)中的电子转移，被认为可以在细胞上进行有效的光催化反应。还测量了 Au@TiO(2)悬浮液的等离子体吸收光谱，以评估光热细胞杀伤。电荷分离、界面电荷转移和光热活性促进了光催化-光热癌症细胞杀伤，比单独的 TiO(2)更有效。发现具有低浓度金的 Au@TiO(2)纳米颗粒（TiO(2)：Au 摩尔比>1：1）的细胞毒性效应为 100%，而商业 TiO(2)（P25）的细胞毒性效应约为 50%。使用单独的 Au 和 TiO(2)进行细胞活力比较研究表明，光催化羟基自由基形成和 Au 等离子体光热热生成的协同效应在癌细胞杀伤中起着至关重要的作用。还根据获得的结果提出了光催化癌症细胞杀伤的合理机制。
