School of Environmental and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, China.
Analyst. 2019 Dec 2;144(24):7489-7497. doi: 10.1039/c9an01541h.
A yolk-shell structured Au@Ag@mSiO2 probe was fabricated by coating a layer of mesoporous silica on the surface of a Au@Ag core-shell nanosphere, followed by partially removing the Ag shell. Mirror symmetrical chiral signals at ∼258 nm in the UV region were observed for the probe upon coupling with cysteine enantiomers on the surface of Au@Ag. The intensity of the CD signal of the probe is enhanced by increasing l/d-Cys concentration, allowing the quantitative determination of the cysteine enantiomers. The developed method shows an excellent linear relationship between the CD signal and l-Cys concentration ranging from 10 μM to 90 μM with a limit of detection of 8.5 μM. In the presence of Cu2+, the CD signal of the probe weakened due to the oxidation of l-cysteine to l-cystine catalyzed by Cu2+. Based on this phenomenon, a new strategy for the detection of Cu2+ can be developed. Under the optimized conditions, the CD signal decreases linearly with the log of the concentration of Cu2+ in the range from 1 to 250 nM with a detection limit of 0.1 nM.
一种蛋黄壳结构的 Au@Ag@mSiO2 探针是通过在 Au@Ag 核壳纳米球表面包覆一层介孔硅，然后部分去除 Ag 壳制得的。当与 Au@Ag 表面的半胱氨酸对映异构体偶联时，探针在紫外区约 258nm 处观察到镜像对称的手性信号。随着 l/d-Cys 浓度的增加，探针的 CD 信号强度增强，允许对半胱氨酸对映异构体进行定量测定。所开发的方法在手性识别方面表现出良好的线性关系，其 CD 信号与 l-Cys 浓度在 10 μM 至 90 μM 范围内呈线性关系，检测限为 8.5 μM。在 Cu2+存在下，由于 Cu2+催化 l-半胱氨酸氧化为 l-胱氨酸，探针的 CD 信号减弱。基于这一现象，可以开发出一种用于检测 Cu2+的新策略。在优化条件下，CD 信号随 Cu2+浓度的对数在 1 至 250 nM 范围内呈线性降低，检测限为 0.1 nM。
