L-半胱氨酸-金属离子配合物的表面增强拉曼光谱研究

发布时间：2018-03-20 05:00

本文选题：表面增强拉曼光谱　切入点：L-半胱氨酸　出处：《光谱学与光谱分析》2017年07期 　论文类型：期刊论文

【摘要】：利用拉曼光谱仪测定L-半胱氨酸(L-Cys)的常规拉曼光谱(NRS)和表面增强拉曼光谱(SERS),发现L-Cys在纳米银棒上有明显的拉曼增强效应,对分子特征峰进行了归属,研究L-Cys在银纳米棒基底表面吸附机理,在固体NRS中在2 576cm~(-1)出处有明显的S—H伸缩振动峰,而SERS中没有出现,实验表明纳米银棒与L-Cys巯基上的S原子形成了Ag—S键,C—O和C—N伸缩振动有明显的增强。在不同pH值条件下,分析了L-Cys的拉曼光谱差异,探讨吸附行为的变化。在pH值为6时,S—H的伸缩振动峰基本消失,形成了稳定的S—Ag键;随着pH值增加趋于碱性时,羧基易失去H原子形成—COO-易与银发生吸附作用且振动峰增强。在pH值为7时,S原子与Ag形成稳定的S—Ag键,C—O和C—N的振动峰也最稳定。选择在pH值为7的条件下,在L-Cys溶液中加入Na+,Mg~(2+)和Cu~(2+)等10种金属盐,发现Al 3+,Cu~(2+),Zn~(2+),Cd~(2+)和Hg~(2+)使L-Cys分子的结构发生了改变,金属离子与L-Cys另一端羧基发生作用,其中Cu~(2+),Zn~(2+),Cd~(2+)和Hg~(2+)随半径增大与S原子的孤电子发生作用越大。探讨了在不同pH值、不同比例和不同浓度下,金属离子与L-Cys作用SERS的变化,随着pH值、比例和浓度的增大,峰的强度有减小趋势。Cu~(2+)与L-Cys作用的SERS信号很弱,Hg~(2+)与L-Cys作用只出现了一个C—O的振动峰,说明Hg~(2+)完全破坏了L-Cys的空间构型。该研究对蛋白质变性等的研究提供了重要参考信息。
[Abstract]:The conventional Raman spectroscopy (NRSs) and surface-enhanced Raman spectroscopy (SERSs) were used to determine L-Cys-L-cysteine (L-Cys). It was found that L-Cys had obvious Raman enhancement effect on silver nanorods, and the molecular characteristic peaks were assigned. The adsorption mechanism of L-Cys on the surface of silver nanorods was studied. The S-H stretching vibration peak was observed in solid NRS at 2576 cm ~ (-1), but not in SERS. The results show that the Ag-S bond C-O and C-N stretching vibration of the nanocrystalline silver rod formed by S atoms on L-Cys sulfhydryl group are obviously enhanced. The Raman spectra of L-Cys are analyzed at different pH values. The change of adsorption behavior is discussed. When the pH value is 6:00, the S-H stretching vibration peak disappears basically, forming a stable S-Ag bond, and when the pH value increases, it tends to be alkaline. It is easy for carboxyl group to lose H atom to form -COO- easily adsorbed with silver and the vibrational peak is enhanced. The vibrational peak of S-Ag bond C-O and C-N formed by S atom with Ag at 7:00 pH is also the most stable. When pH value is 7, the vibration peak of C-O and C-N is also the most stable. It was found that the structure of L-Cys was changed by adding 10 kinds of metal salts, such as Na ~ (2 +) (mg ~ (2)) and Cu~(2), and the metal ions acted on the other end of L-Cys, and the structure of L-Cys was changed. The effects of Cu~(2 and Hg~(2) on the generation of solitary electrons in S atoms are increased with the increase of radius. The changes of SERS interaction between metal ions and L-Cys at different pH values, different ratios and different concentrations are discussed, and with the increase of pH value, ratio and concentration, the effect of SERS on L-Cys is discussed. The intensity of the peak tends to decrease. The SERS signal interacting with L-Cys is very weak. There is only one C-O vibration peak in the interaction with L-Cys. The results show that Hg~(2 completely destroys the spatial configuration of L-Cys, and this study provides important reference information for the study of protein denaturation.
【作者单位】：发光与实时分析教育部重点实验室西南大学化学化工学院;
【基金】：国家自然科学基金项目(21175015,21475014)资助
【分类号】：O641.4;O657.37

【相似文献】