一种基于多羧基荧光共轭聚电解质的氨基酸检测新方法

基于多羧基荧光共轭聚电解质PPE-(COOK)₄, 发展了一种检测半胱氨酸(Cys)和组氨酸(His)的简便方法. 该方法以PPE-(COOK)₄与Cu²⁺所构成的猝灭体系为基础, 当体系中存在半胱氨酸或组氨酸时, PPE-(COOK)₄/Cu²⁺体系的荧光恢复, 从而实现对上述氨基酸的测定. 由于PPE-(COOK)₄具有类似四乙酸乙二胺(EDTA)的螯状侧链结构, 使其在磷酸盐缓冲液(PBS, 10 mmol/L, pH=7.4)中对Cu²⁺具有超高的灵敏度和选择性, 因此可以借助各种金属掩蔽离子来提高氨基酸检测的特异性. 实验结果表明, 在PPE-(COOK)₄/Cu²⁺体系中引入Ni²⁺或Hg²⁺后, 可分别实现对半胱氨酸和组氨酸的特异性检测, 线性范围分别为1~5和0.5~2.5 μmol/L, 检出限分别为0.15和0.04 μmol/L.

Specific Assay of Amino Acids Based on a Fluorescent Conjugated Polyelectrolyte with Multi-carboxylates

A simple assay for cysteine(Cys) and histidine(His) based on a conjugated polyelectrolyte with multi-carboxylate groups was developed.The proposed approach takes advantage of the emission quenching of PPE-(COOK)4 caused by Cu2+,which can be efficiently restored in the presence of Cys or His.Thus,the rapid assay of both amino acids can be carried out by measuring the fluorescence recovery.With the high similarity between the polymer’s side groups and EDTA,PPE-(COOK)4 in phosphate buffer solution exhibits not only high sensitivity but remarkable specificity towards Cu2+,which makes it possible to introduce various shielding metals for improving the selectivity of Cys and His assays.The results demonstrated that both Cys and His can be assayed sensitively and selectively by adding Ni2+ or Hg2+ to PPE-(COOK)4/Cu2+ system.The limit of detection is 0.15 μmol/L for Cys and 0.04 μmol/L for His,with the linear range of 1—5 μmol/L and 0.5—2.5 μmol/L,respectively.