基于表面富Cd^2＋的硫化镉量子点荧光增强测定半胱氨酸

Determination of Cysteine Based on Fluorescence Enhancement of CdS Quantum Dots with Cd^(2+) Rich Surface

采用一步法可控合成了表面富Cd2+的水溶性荧光硫化镉量子点,并成功用于半胱氨酸测定。通过控制镉-硫前驱体合适比例,使合成的量子点表面富含Cd2+,它们能与半胱氨酸分子中巯基结合引起体系量子点荧光增强,由此实现半胱氨酸的选择性定量分析检测。在pH=2.87的B-R缓冲体系中,测定半胱氨酸的线性区间分别为0.01～5.0μmol/L和5.0～100μmol/L;检出限(3σ)为3.3 nmol/L,且其它氨基酸干扰小,可应用于混合氨基酸合成样品、复方氨基酸注射液和人血清实际样品中半胱氨酸的检测。

Water-soluble CdS quantum dots with Cd2＋ rich surface,synthesized via a controllable one-step approach,have been successfully employed for the determination of cysteine.Under proper concentration ratio of cadmium and sulfur precursors,excessive Cd2＋ on the surface of CdS can interact specifically with the mercapto group in cysteine molecule,resulted in the enhancement of fluorescence signals.Therefore,it can be applied in the selective quantitative detection of cysteine.In the B-R buffer medium with pH at 2.87,the enhancement of fluorescence intensities were linear with the concentration of cysteine in the range of 0.01-5.0 and 5.0-100 μmol/L,and the detection limit（3σ） was 3.3 nmol/L.Without the interference of other amino acids,the proposed method can be applied to the detection of cysteine in synthetic or real samples,such as amino acid mixture,compound amino acids injection and human serum.