绿色合成银纳米粒子及其在SERS中的应用

采用无毒、绿色的酪氨酸作为还原剂和稳定剂，在碱性条件下还原硝酸银，经60 ℃恒温水浴处理20 min，成功地合成了银纳米粒子。混合溶液颜色由淡黄色变为棕黄色直观地呈现了银纳米粒子的生成。利用紫外可见吸收光谱(UV-Vis)和透射电子显微镜(TEM)对制备样品进行分析和表征。粒子的UV-Vis吸收在412 nm附近。TEM图像显示，银纳米粒子的形状近似球形，粒子直径在15～25 nm。分别以结晶紫(CV)和叶酸(FA)为探测分子，进一步研究了该银纳米粒子的表面增强拉曼散射(SERS)效应。实验结果表明，该合成方法不仅方便、快速、绿色环保，而且合成的银纳米粒子对CV和FA分子有很好的SERS效应。

Green Synthesis of Silver Nanoparticles and Their Application in SERS

In the present paper, we have successfully synthesized silver nancomparticles by reducing of silver nitrate in alkaline solution via 60 ℃ water bath for 20 minutes with the use of tyrosine, a nontoxic and green macromolecule, as a reducing and stabilizing agent. The formation of silver nanoparticles was observed visually by color change of the solutions (from faint yellow to brown yellow). The morphologies of the Ag NPs were characterized by UV-Vis absorption spectroscopy and transmission electron microscopy (TEM). The UV-Vis absorption peak of silver nanoparticles located at 412 nm. The TEM image of silver nanoparticles indicated that the diameters of nanospheres are mainly in the range 15～25 nm. In order to evaluate the SERS activity of the silver nancomparticles, crystal violet and folic acid were used as the Raman probe molecule. The experimental results indicated that there are two ascendancies, firstly, the approach is convenient and the reaction condition is facile, secondly, tyrosine is a water-soluble, nontoxic and biodegradable macromolecule, which makes this approach provide a green strategy to prepare Ag NPs. Significantly, the synthesized Ag NPs exhibits good surface enhanced Raman scattering (SERS) activity as SERS substrates to detect crystal violet and folic acid in aqueous solution.