Colorimetric determination of cysteine based on Au@Pt nanoparticles as oxidase mimetics with enhanced selectivity

• Published in: Mikrochimica acta (1966) Vol. 189; no. 1; p. 13
• Main Authors: Chi, Hui, Cui, Xiaoqian, Lu, Yongzhuang, Yu, Miao, Fei, Qiang, Feng, Guodong, Shan, Hongyan, Huan, Yanfu
• Format: Journal Article
• Language: English
• Published: Vienna Springer Vienna 01.01.2022; Springer; Springer Nature B.V
• Subjects: Absorption; Analytical Chemistry; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Colorimetry; Cysteine; Cystine; Dissolved oxygen; Glutathione; Gold; Hydrogen peroxide; Microengineering; Nanochemistry; Nanoparticles; Nanotechnology; Original Paper; Oxidase; Oxidases; Oxidation; Platinum; Selectivity; Cysteine; Nanozymes; Homocysteine; Au@Pt nanoparticles; Glutathione; Colorimetric determination
• ISSN: 0026-3672; 1436-5073; 1436-5073
• DOI: 10.1007/s00604-021-05091-7

A H 2 O 2 -free colorimetric protocol based on urchin-like Au@Pt nanoparticles (Au@Pt NPs) has been developed for the sensitive and selective determination of cysteine (Cys). We verified the intrinsic oxidase-like activity of the Au@Pt NPs. They can act as artificial mimic oxidases to catalyse the oxidization of 3,3′,5,5′-tetramethylbenzidine (TMB) with the assistance of dissolved oxygen, avoiding the use of H 2 O 2 in the colorimetric determination of Cys. In addition, the discrimination of Cys from the other two biothiol analogues, homocysteine and glutathione, can be easily realized through a simple ageing process. HNO 3 is added to this colorimetric system to terminate the reaction by oxidizing ox-TMB (oxidized form of TMB) to diphenoquinone (DPQ), thus generating a characteristic absorption peak of DPQ at 450 nm. By recording the absorbance at 450 nm, interference from the aggregated Au@Pt NPs (absorption peak at 670 nm) when 650 nm (the characteristic absorption peak of ox-TMB) is used as the absorption wavelength can be eliminated. We investigated this H 2 O 2 -free colorimetric protocol and obtained high sensitivity, with a detection limit of 1.5 nM and relatively high selectivity. The analytical performance for real samples was further explored. The Au@Pt NP–based H 2 O 2 -free colorimetric protocol is of great significance for the sensitive and selective determination of Cys in practical samples in different scenarios. Graphical abstract