基于L-Cys@Ag分析吲哚美辛的表面增强拉曼光谱

联合紫外、拉曼光谱及其在L-半胱氨酸/银传感器(L-Cys@Ag)的表面增强拉曼散射(SERS)光谱表征吲哚美辛, 并与固体吲哚美辛的常规拉曼光谱(NRS)进行对比, 发现L-Cys@Ag对吲哚美辛有明显拉曼信号放大, 但其特征峰几乎不产生位移。研究不同酸碱环境下, L-Cys@Ag的吸附模型, 分析吲哚美辛在L-Cys@Ag上的拉曼光谱和SERS光谱, 归属拉曼特征峰。结果显示, L-半胱氨酸与银主要以Ag-S键的方式形成稳定吸附, 但是中性和碱性条件时-COO-也会吸附到银表面。结果表明: 半胱氨酸中的氨基与吲哚美辛中的羧基氧、苯环中的π电子发生吸附, 整体能量下降, 使结构更加稳定。加入牛血清白蛋白(BSA)后, pH为5时, SERS强度明显减弱。在pH为7和9时, N-H伸缩振动和酰胺Ⅱ振动明显增强, 吲哚美辛的苯环和吲哚环的特征峰振动消失。其原因是吲哚美辛的苯环和吲哚环进攻BSA后, 吲哚美辛特征振动消失, 但是吲哚美辛中的氮, 羰基与BSA中氨基吸附, 使得C-N和-COO-的SERS信号稳定。这为将来吲哚美辛以及相关非淄体消炎药的改良和新药的研究提供了可靠的鉴别和分析方法。

Analysis of Indomethacin by Surface Enhanced Raman Spectroscopy Based on L-Cys@Ag

In this paper, indomethacin are characterized by the spectroscopy of UV and Raman and surface enhanced Raman scattering (SERS) on the substrate of L-Cys@Ag. And compared with the conventional Raman spectra (NRS) of solid indomethacin, it was found that L-Cys@Ag had significant Raman enhancement for indomethacin, but the characteristic peak was almost unchanged. The Raman spectra of indomethacin on L-Cysteine/silver were analyzed by the adsorption model of L-Cysteine and silver under acidic and basic conditions. The results showed that L-Cysteine and silver were mainly adsorbed by Ag-S bonds, but neutral and alkaline conditions carboxyl were also adsorbed to the surface of silver. The reson why the overall energy decreases is that the amino groups in the cysteine react with the carboxyl groups in the indomethacin and the π electrons in the benzene ring. After adding bovine serum albumin (BSA), the SERS intensity was significantly decreased at pH 5. At pH 7, and pH 9, the NH stretching vibration and amide II vibration were obviously enhanced, as well as the benzene ring and indole ring of indomethacin. The peak vibration disappeared due to the disappearance of indole mesacin, and the nitrogen and carbonyl groups in indomethacin were adsorbed by amino groups in BSA, and the C-N And -COO’s SERS signal is stable. This provides a reliable method for the identification and analysis of the future improvement of indomethacin and related non-Zhiban anti-inflammatory drugs and new drugs.