本文以结晶紫作为探针分子, 研究了以金溶胶膜、pH=6以及pH=13的金溶胶溶液为活性基底的表面增强拉曼光谱的增强效果。采用化学还原法制备金溶胶, 加入氢氧化钠改变其pH值, 并以自组装法制备金溶胶膜。通过比较金溶胶膜、pH=6及pH=13时金溶胶溶液的增强因子以及在这三种金溶胶基底上结晶紫的检测限, 分析不同活性基底增强效果的差异。三种活性基底的增强因子分别可达到5.9×103、1.5×105、2.3×107, pH=13的金溶胶溶液有最佳的增强效果。以这三种金溶胶为基底对结晶紫进行表面增强拉曼光谱探测, 可得到检测限为70.7 nmol/L、9.6 nmol/L、1.8 nmol/L。结果表明, 金溶胶溶液的增强效果明显优于金溶胶膜, 而通过改变金溶胶体系的pH值可以改变金纳米颗粒的聚合程度及对探测物的吸附特性从而获得更高灵敏度的活性基底。

In this paper, the SERS enhancement of gold colloid film and gold colloid solution under the condition of pH=6 and pH=13 was studied by using crystal violet (CV) as the probe molecule. Gold colloid solution was prepared using chemical reduction method and its pH value was changed by adding NaOH solution. Gold colloid films were prepared by the self-assembly method. The enhancements of gold colloid film and gold colloid solution with pH=6 and pH=13 were evaluated by comparing their enhancement factors (EFs) and the limits of detection (LODs). The EFs of these three substrates were 5.9×103, 1.5×105 and 2.3×107 respectively and their LODs of CV were 70.7 nmol/L, 9.6 nmol/L and 1.8 nmol/L respectively. The results show that the enhancement of gold colloid solution is better than the gold colloid film. By changing the pH value of gold colloid solution, the aggregation degree and the adsorption properties for adsorbate of gold nanoparticles have been changed as well so that the enhancement of gold colloid solution can be significantly improved.