title: Hg2+-mediated aggregation of gold nanoparticles for colorimetric screening of biothiols.
abstract: In this work, we report a colorimetric assay for the screening of biothiols including glutathione (GSH), cysteine (Cys), and homocysteine (Hcys) based on Hg(2+)-mediated aggregation of gold nanoparticles (AuNPs). Hg(2+) can induce aggregation of thiol-containing naphthalimide (1) capped AuNPs due to the cross-linking interactions from the resulting "thymine-Hg(2+)-thymine" (T-Hg(2+)-T) analogous structure. When Hg(2+) is firstly treated with biothiols, followed by mixing with 1-capped AuNPs suspension, AuNPs undergo a transformation from an aggregation to a dispersion state depending on the concentration of biothiols. This anti-aggregation or re-dispersion of AuNPs is due to the higher affinity of Hg(2+) for biothiols relative to compound 1. The corresponding color variation in the process of anti-aggregation of AuNPs can be used for the quantitative screening of biothiols through UV-vis spectroscopy or by the naked eye. Under optimized conditions, a good linear relationship in the range of 0.025-2.28 μM is obtained for GSH, 0.035-1.53 μM for Cys, and 0.040-2.20 μM for Hcys. The detection limits of this assay for GSH, Cys, and Hcys are 17, 9, and 18 nM, respectively. This colorimetric assay exhibits a high selectivity and sensitivity with tunable dynamic range. The proposed method has been successfully used in the determination of total biothiol content in human urine samples.
authors.affiliation: Shanghai Key Laboratory of Functional Materials Chemistry, Department of Chemistry, East China University of Science and Technology, Shanghai, 200237, PR China.
authors.forename: Hu
authors.initials: H
authors.lastname: Xu
authors.forename: Yiwen
authors.initials: Y
authors.lastname: Wang
authors.forename: Xiaomei
authors.initials: X
authors.lastname: Huang
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
authors.forename: Hua
authors.initials: H
authors.lastname: Zhang
authors.forename: Xinhua
authors.initials: X
authors.lastname: Zhong
mesh_terms: D003124:Colorimetry / Q000379:methods*; D006046:Gold / Q000737:chemistry; D006801:Humans; D057230:Limit of Detection; D008297:Male; D008628:Mercury / Q000737:chemistry; D053768:Metal Nanoparticles / Q000737:chemistry*; D012680:Sensitivity and Specificity; D013438:Sulfhydryl Compounds / Q000032:analysis / Q000652:urine*
chemical_list: D013438:Sulfhydryl Compounds; D006046:Gold; D008628:Mercury