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目的:考察纳米银溶胶的稳定性与影响其稳定性的因素,以及其稳定性对于表面增强拉曼光谱检测的影响。方法:用电子透射显微镜和zeta电势对银溶胶及加入电解质或酸碱后的银溶胶进行了表征,并用zeta电势对不同温度下不同时间段的银溶胶进行了稳定性考察。选择了苏丹红III、盐酸西布曲明、盐酸吡格列酮3个化合物做为探针分子,对比了它们在分散的银溶胶及沉降后的银溶胶中的表面增强拉曼光谱的差异。并比较分析了它们在不同温度及不同时间段测定的表面增强拉曼光谱。结果:在温度较低的环境下,2个月之内的银溶胶基本能保持稳定,2个月之后,稳定性显著下降。而在温度较高的环境下,银溶胶极易沉降失活。加入电解质或酸碱后,银溶胶颗粒迅速凝聚。分散的银溶胶对于苏丹红III、盐酸西布曲明、盐酸吡格列酮3个化合物均有较理想的增强效应,沉降后的银溶胶对3个化合物的增强均不明显。环境温度变化对于表面增强拉曼光谱检测的影响基本可以忽略。表面增强拉曼光谱测定的最佳时间为样品与银胶混合后的1 h内,时间过长,纳米沉降使得光谱信号显著减弱。结论:外来酸碱对银溶胶稳定性的影响比一般的电解质要大。时间和温度也是影响溶胶稳定性的重要因素之一。分散的银溶胶具有较强的拉曼增强活性,沉降后的银溶胶增强活性明显下降。
OBJECTIVE: To investigate the stability of nano-silver sol and the factors affecting the stability of nano-silver sol and the influence of its stability on the surface-enhanced Raman spectroscopy. Methods: The silver sol was characterized by means of electron transmission microscope and zeta potential. The stability of silver sol was characterized by zeta potential at different temperatures. The three compounds Sudan III, sibutramine hydrochloride and pioglitazone hydrochloride were selected as probe molecules, and their differences in surface-enhanced Raman spectra were compared between the dispersed silver sol and the precipitated silver sol. Their surface-enhanced Raman spectra were compared and analyzed at different temperatures and different time periods. Results: In a low temperature environment, the silver sol remained stable within 2 months and its stability remarkably decreased after 2 months. In the high temperature environment, the silver sol can easily settle inactivation. After adding electrolyte or acid-base, silver sol particles agglomerate rapidly. Dispersed silver sol had better enhancement effect on three compounds of Sudan III, sibutramine hydrochloride and pioglitazone hydrochloride, and the silver sol had no obvious enhancement on the three compounds after settling. The effect of ambient temperature change on surface-enhanced Raman spectroscopy can be neglected. The best time for surface-enhanced Raman spectroscopy was within 1 h after the sample was mixed with the silver paste, and the time was too long for the nano-particles to settle, resulting in a significant decrease of the spectral signal. Conclusion: The effect of extraneous acid and base on the stability of silver sol is larger than that of common electrolytes. Time and temperature are also one of the important factors affecting sol stability. Dispersed silver sol had stronger Raman-enhancing activity, and the activity of silver sol after settling decreased obviously.