A novel fluorescence probe capable of discriminatively and simultaneously detecting Cys, Hcy and GSH has been developed. This specially designed probe can selectively react with Cys and Hcy to form thiazinane and thiazolidine derivatives in the presence of diverse amino acids, protected Cys and glucose and display the expected aggregation-induced emission (AIE) properties. Relying on the differences in kinetics, Cys can be easily and discriminately detected over Hcy by the observation of FL responses. GSH shows great interference with the detection of Cys and Hcy and it can be quantitatively detected by the FL spectroscopic titration method. The threshold of the FL turn-off concentration for GSH is measured to be 1 mM. This is the first report of using a single fluorescent probe to discriminately detect Cys, Hcy and GSH by FL turn-on and turn-off strategies. The discrimination relies on the reaction-dependent fluorophore aggregation, or the solubility of adducts of the probe molecule and analytes. The present strategy is intrinsically a fluorescent titration, which combines the high sensitivity of FL spectroscopy and the reliability of precipitate titration methodology. The threshold concentration of Cys (375 μM, at which the FL is turned-on) coincides with the upper margin of the deficient Cys levels in human plasma, and the primary investigation of the FL response to deproteinized human plasma indicates that this FL probe is a promising one for the discriminatory detection of Cys over Hcy and GSH on a clinical level.
一种新型荧光探针被开发出来,能够选择性且同时检测半胱
氨酸(Cys)、同半胱
氨酸(Hcy)和
谷胱甘肽(GSH)。该特别设计的探针可以在多种
氨基酸、保护的Cys和
葡萄糖存在的情况下,选择性地与Cys和Hcy反应,形成
噻唑烷和
噻唑烷衍
生物,并展示出预期的聚集诱导发光(AIE)特性。依赖于动力学的差异,通过观察荧光(FL)响应,Cys可以被轻松且选择性地检测出来,而Hcy则较难。GSH对Cys和Hcy的检测产生了很大的干扰,但可以通过荧光光谱滴定法进行定量检测。GSH的荧光熄灭浓度阈值测定为1 mM。这是首次报告使用单一荧光探针通过荧光开关策略选择性检测Cys、Hcy和GSH。该选择性依赖于反应依赖的荧光团聚集或探针分子与分析物的加合物的溶解度。目前的策略本质上是一种荧光滴定,结合了荧光光谱的高灵敏度和沉淀滴定方法的可靠性。Cys的阈值浓度(375 μM,荧光开启时)恰好与人类血浆中缺乏Cys
水平的上限相吻合,初步研究表明该荧光探针在去蛋白质化人类血浆中的荧光响应,表明其在临床上选择性检测Cys相对于Hcy和GSH的潜力。