荧光共振能量转移高灵敏检测汞离子和半胱氨酸

FITC as a fluorescence probe for sensitive detection of Hg^(2+) and L-Cysteine

开发了一种简单快速的荧光探针,该探针在DNA的3’端标记荧光素并利用[T-Hg(II)-T]复合结构对荧光进行猝灭,荧光素与[T-Hg(II)-T]复合结构之间发生荧光共振能量转移。在对探针链长度以及pH和反应时间等实验条件进行优化后,该荧光探针对汞离子具有较高的选择性,用于汞离子分析时检出限可以达到纳摩尔级。当加入半胱氨酸,由于形成了半胱氨酸-汞离子复合结构,[T-Hg(II)-T]复合结构被破坏,荧光强度大量的恢复。利用此原理可以对半胱氨酸进行分析,检出限也可以达纳摩尔级。该荧光探针利用一条廉价的T碱基适配体链所构筑,相比传统的荧光探针有着独特的优势。

A simple and fast new fluorescence probe in which fluorescein（FAM） attached to its 3＇end acting as a fluorophore and a bridged thymidine-Hg-thymidine（T-Hg-T） complex acting as a quencher is designed.The fluorescence resonance energy transfer（FRET） between the fluorophore and the quencher results in annihilation of the FAM fluorescence.Experimental conditions that influence the fluorescence quenching,such as number of thymidine bases,pH value,and reaction time have been optimized.The fluorescence probes was found to be highly selective for Hg^2＋ among a number of metal ions investigated.Hg^2＋ concentration atananomolar level could be determined.In the presence of Cysteine,the FAM fluorescence can be largely restored due to L-Cysteine-Hg formation.L-Cysteine concentration at a nanomolar level could be determined using the present method for Cysteine assay is can determine Cysteine concentration at a nanomolar level.The substitution of the quencher group in a conventional fluorescence probe molecule with simple thymidine bases affords an inexpensive oligonucleotides that retains the unique property of the fluorescence probe molecule.