title: Discriminatory detection of cysteine and homocysteine based on dialdehyde-functionalized aggregation-induced emission fluorophores.
abstract: We demonstrate a concept-proof work of using fluorescence (FL) "turn-on" probes for the discriminatory detection of cysteine (Cys) over homocysteine (Hcy). The fluorogens are provided with aggregation-induced emission (AIE) characteristic and functionalized with two aldehyde-groups (DMTPS-ALD and TPE-ALD). All the detections were carried out in a biocompatible medium (10 mM HEPES buffer and DMSO, pH 7.4). In principle, the formation of thiazinane/thiazolidine through the chemical reaction of aldehydes on the probe molecules and the residue of Cys/Hcy determines the selective recognition of Cys and Hcy over other amino acids and glucose. The FL responses originate from the AIE property of thiazinane/thiazolidine resultants, which have low solubility and precipitate (aggregate) in the detection medium. The discrimination between Cys and Hcy comes from the difference in reaction kinetics of TPE-ALD/DMTPS-ALD with Cys and Hcy, thereby the FL responses show different time courses and intensity enhancement. It is worth noting that TPE-ALD outshined the other two probes in performance with fast response, a high FL enhancement up to 16-fold, high sensitivity, and good specificity and selectivity. Moreover, its FL response threshold at 250 μM is very close to the lower limit of the normal level of Cys in human plasma, which implies that TPE-ALD could be applied as a potential indicator of Cys deficiency.
authors.affiliation: MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science & Engineering, Zhejiang University, No. 38, Zheda Road, Hangzhou 310027, PR China.
authors.forename: Ju
authors.initials: J
authors.lastname: Mei
authors.forename: Yijia
authors.initials: Y
authors.lastname: Wang
authors.forename: Jiaqi
authors.initials: J
authors.lastname: Tong
authors.forename: Jian
authors.initials: J
authors.lastname: Wang
authors.forename: Anjun
authors.initials: A
authors.lastname: Qin
authors.forename: Jing Zhi
authors.initials: JZ
authors.lastname: Sun
authors.forename: Ben Zhong
authors.initials: BZ
authors.lastname: Tang
mesh_terms: D000447:Aldehydes / Q000737:chemistry*; D002021:Buffers; D002623:Chemistry Techniques, Analytical / Q000295:instrumentation*; D003545:Cysteine / Q000032:analysis* / Q000097:blood / Q000737:chemistry*; D004121:Dimethyl Sulfoxide / Q000737:chemistry; D005456:Fluorescent Dyes / Q000737:chemistry*; D006710:Homocysteine / Q000032:analysis* / Q000097:blood / Q000737:chemistry*; D006801:Humans; D007536:Isomerism; D013050:Spectrometry, Fluorescence
chemical_list: D000447:Aldehydes; D002021:Buffers; D005456:Fluorescent Dyes; D006710:Homocysteine; D003545:Cysteine; D004121:Dimethyl Sulfoxide