Tachikawa Shingo, Noguchi Atsushi, Tsuge Takeharu, Hara Masahiko, Odawara Osamu, Wada Hiroyuki
Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan.
Materials (Basel). 2011 Jun 17;4(6):1132-1143. doi: 10.3390/ma4061132.
Optical properties of ZnO nanoparticles capped with polymers were investigated. Polyethylene glycol (PEG) and polyvinyl pyrrolidone (PVP) were used as capping reagents. ZnO nanoparticles were synthesized by the sol-gel method. Fluorescence and absorption spectra were measured. When we varied the timing of the addition of the polymer to the ZnO nanoparticle solution, the optical properties were drastically changed. When PEG was added to the solution before the synthesis of ZnO nanoparticles, the fluorescence intensity increased. At the same time, the total particle size increased, which indicated that PEG molecules had capped the ZnO nanoparticles. The capping led to surface passivation, which increased fluorescence intensity. However, when PEG was added to the solution after the synthesis of ZnO nanoparticles, the fluorescence and particle size did not change. When PVP was added to the solution before the synthesis of ZnO nanoparticles, aggregation of nanoparticles occurred. When PVP was added to the solution after the synthesis of ZnO nanoparticles, fluorescence and particle size increased. This improvement of optical properties is advantageous to the practical usage of ZnO nanoparticles, such as bioimaging.
研究了用聚合物包覆的ZnO纳米颗粒的光学性质。使用聚乙二醇（PEG）和聚乙烯吡咯烷酮（PVP）作为包覆试剂。通过溶胶-凝胶法合成了ZnO纳米颗粒。测量了荧光光谱和吸收光谱。当我们改变聚合物添加到ZnO纳米颗粒溶液中的时间时，光学性质发生了显著变化。当在ZnO纳米颗粒合成之前将PEG添加到溶液中时，荧光强度增加。同时，总粒径增大，这表明PEG分子包覆了ZnO纳米颗粒。这种包覆导致表面钝化，从而增加了荧光强度。然而，当在ZnO纳米颗粒合成之后将PEG添加到溶液中时，荧光和粒径没有变化。当在ZnO纳米颗粒合成之前将PVP添加到溶液中时，纳米颗粒发生聚集。当在ZnO纳米颗粒合成之后将PVP添加到溶液中时，荧光和粒径增加。这种光学性质的改善有利于ZnO纳米颗粒的实际应用，如生物成像。
