Zhu Zhi-liang, Gao Jun-ying, Li Feng-ting, Zhang Bing-ru
Department of Chemistry, Tongji University, Shanghai 200092, China.
Guang Pu Xue Yu Guang Pu Fen Xi. 2004 Jan;24(1):68-70.
The adsorption state and the characteristics of L-aspartic acid adsorbed on silver sol were studied by the Surface-Enhanced Raman Scattering (SERS) method. Strong Raman signals were detected in the experiments. The results suggested that L-aspartic acid adsorbed on the silver surfaces through carboxyl and nitrogen atoms since the signals were mainly due to the carboxyl and the nitrogen of the molecule of L-aspartic acid. The adsorption of carboxyl on the silver surfaces is chemical adsorption, which is based on the mechanism of charge-transfer, while the adsorption of nitrogen on the silver surfaces is physical type, which is due to the electromagnetic mechanism. The intensity of surface-enhanced Raman scattering of L-aspartic acid adsorbed on silver surface was also analyzed, and it was found that the intensity of surface-enhance Raman scattering will change with different concentrations of L-aspartic acid adsorbed on the silver surfaces. The intensity will reach the top value when the concentration of L-aspartic acid was 10(-3) mol x L(-1). When the concentration of L-aspartic acid decreased to 10(-4) mol x L(-1), the intensity of surface-enhanced Raman scattering became a little weaker than that with 10(-3) mol x L(-1). With further decrease in the concentration of L-aspartic acid, the intensity of surface-enhanced Raman scattering also decreased gradually. When the concentration of L-aspartic acid decreased to 10(-6) mol x L(-1), the intensity of surface-enhanced Raman scattering was very low. The above study will be helpful to the further study of peptide and other complex biological systems.
采用表面增强拉曼散射（SERS）方法研究了L-天冬氨酸在银溶胶上的吸附状态及吸附特性。实验中检测到了强烈的拉曼信号。结果表明，L-天冬氨酸通过羧基和氮原子吸附在银表面，因为信号主要源于L-天冬氨酸分子的羧基和氮。羧基在银表面的吸附是基于电荷转移机制的化学吸附，而氮在银表面的吸附是基于电磁机制的物理吸附类型。还分析了吸附在银表面的L-天冬氨酸的表面增强拉曼散射强度，发现表面增强拉曼散射强度会随着吸附在银表面的L-天冬氨酸浓度不同而变化。当L-天冬氨酸浓度为10(-3) mol·L(-1)时，强度达到最大值。当L-天冬氨酸浓度降至10(-4) mol·L(-1)时，表面增强拉曼散射强度比10(-3) mol·L(-1)时略弱。随着L-天冬氨酸浓度进一步降低，表面增强拉曼散射强度也逐渐降低。当L-天冬氨酸浓度降至10(-6) mol·L(-1)时，表面增强拉曼散射强度非常低。上述研究将有助于对肽和其他复杂生物体系的进一步研究。
