title: Bioinspired near-infrared-excited sensing platform for in vitro antioxidant capacity assay based on upconversion nanoparticles and a dopamine-melanin hybrid system.
abstract: A novel core-shell structure based on upconversion fluorescent nanoparticles (UCNPs) and dopamine-melanin has been developed for evaluation of the antioxidant capacity of biological fluids. In this approach, dopamine-melanin nanoshells facilely formed on the surface of UCNPs act as ultraefficient quenchers for upconversion fluorescence, contributing to a photoinduced electron-transfer mechanism. This spontaneous oxidative polymerization of the dopamine-induced quenching effect could be effectively prevented by the presence of various antioxidants (typically biothiols, ascorbic acid (Vitamin C), and Trolox). The chemical response of the UCNPs@dopamine-melanin hybrid system exhibited great selectivity and sensitivity toward antioxidants relative to other compounds at 100-fold higher concentration. A satisfactory correlation was established between the ratio of the "anti-quenching" fluorescence intensity and the concentration of antioxidants. Besides the response of the upconversion fluorescence signal, a specific evaluation process for antioxidants could be visualized by the color change from colorless to dark gray accompanied by the spontaneous oxidation of dopamine. The near-infrared (NIR)-excited UCNP-based antioxidant capacity assay platform was further used to evaluate the antioxidant capacity of cell extracts and human plasma, and satisfactory sensitivity, repeatability, and recovery rate were obtained. This approach features easy preparation, fluorescence/visual dual mode detection, high specificity to antioxidants, and enhanced sensitivity with NIR excitation, showing great potential for screening and quantitative evaluation of antioxidants in biological systems.
authors.affiliation: State Key Laboratory for Physical Chemistry of Solid Surfaces, Department of Chemistry, College of Chemistry and Chemical Engineering, and ‡Department of Biomaterials, College of Materials, Xiamen University , Xiamen 361005, P. R. China.
authors.forename: Dong
authors.initials: D
authors.lastname: Wang
authors.forename: Chuan
authors.initials: C
authors.lastname: Chen
authors.forename: Xuebin
authors.initials: X
authors.lastname: Ke
authors.forename: Ning
authors.initials: N
authors.lastname: Kang
authors.forename: Yuqing
authors.initials: Y
authors.lastname: Shen
authors.forename: Yongliang
authors.initials: Y
authors.lastname: Liu
authors.forename: Xi
authors.initials: X
authors.lastname: Zhou
authors.forename: Hongjun
authors.initials: H
authors.lastname: Wang
authors.forename: Changqing
authors.initials: C
authors.lastname: Chen
authors.forename: Lei
authors.initials: L
authors.lastname: Ren
mesh_terms: D000975:Antioxidants / Q000032:analysis*; D032701:Biomimetics / Q000379:methods; D015374:Biosensing Techniques / Q000379:methods; D004298:Dopamine / Q000737:chemistry* / Q000528:radiation effects; D005456:Fluorescent Dyes / Q000737:chemistry*; D007259:Infrared Rays; D008543:Melanins / Q000737:chemistry* / Q000528:radiation effects; D053758:Nanoparticles / Q000737:chemistry* / Q000528:radiation effects / Q000648:ultrastructure; D013050:Spectrometry, Fluorescence / Q000379:methods*
chemical_list: D000975:Antioxidants; D005456:Fluorescent Dyes; D008543:Melanins; D004298:Dopamine
keywords: antioxidant capacity assay; biothiols; dopamine; melanin; near-infrared; upconversion nanoparticles