Jiang Xingya, Du Bujie, Yu Mengxiao, Jia Xun, Zheng Jie
Department of Chemistry and Biochemistry, The University of Texas at Dallas, 800 W. Campbell Rd., Richardson, TX 75080, USA.
Department of Radiation Oncology, The University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA.
J Innov Opt Health Sci. 2016 Jul;9(4):16420031-16420038. doi: 10.1142/S1793545816420037. Epub 2016 May 13.
Gold nanoparticles (AuNPs) could serve as potential radiotherapy sensitizers because of their exceptional biocompatibility and high-Z material nature; however, since and behaviors of AuNPs are determined not only by their particle size but also by their surface chemistries, whether surface ligands can affect their radiosensitization has seldom been investigated in the radiosensitization of AuNPs. By conducting head-to-head comparison on radiosensitization of two kinds of ultrasmall (~2 nm) near-infrared (NIR) emitting AuNPs that are coated with zwitterionic glutathione and neutral polyethylene glycol (PEG) ligands, respectively, we found that zwitterionic glutathione coated AuNPs (GS-AuNPs) can reduce survival rates of MCF-7 cells under irradiation of clinically used megavoltage photon beam at low dosage of ~2.25 Gy. On the other hand, PEG-AuNPs can serve as a radiation-protecting agent and enabled MCF-7 cells more resistant to the irradiation, clearly indicating the key role of surface chemistry in radiosensitization of AuNPs. More detailed studies suggested that such difference was independent of cellular uptake and its efficiency, but might be related to the ligand-induced difference in photoelectron generation and/or interactions between AuNPs and X-ray triggered reactive oxygen species (ROS).
金纳米颗粒（AuNPs）因其卓越的生物相容性和高Z材料性质，可作为潜在的放射治疗增敏剂；然而，由于AuNPs的行为不仅取决于其粒径，还取决于其表面化学性质，在AuNPs的放射增敏作用中，表面配体是否会影响其放射增敏作用鲜有研究。通过对分别包覆两性离子型谷胱甘肽和中性聚乙二醇（PEG）配体的两种超小（约2 nm）近红外（NIR）发射AuNPs的放射增敏作用进行直接比较，我们发现，在临床使用的兆伏级光子束以约2.25 Gy的低剂量照射下，包覆两性离子型谷胱甘肽的AuNPs（GS-AuNPs）可降低MCF-7细胞的存活率。另一方面，PEG-AuNPs可作为辐射防护剂，使MCF-7细胞对辐射更具抗性，这清楚地表明了表面化学在AuNPs放射增敏作用中的关键作用。更详细的研究表明，这种差异与细胞摄取及其效率无关，但可能与配体诱导的光电子产生差异和/或AuNPs与X射线触发的活性氧（ROS）之间的相互作用有关。
