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Fluorescein as a Visible‐Light‐Induced Oxidase Mimic for Signal‐Amplified Colorimetric Assay of Carboxylesterase by an Enzymatic Cascade Reaction
Author(s) -
Liu Li,
Sun Chaoqun,
Yang Juan,
Shi Ying,
Long Yijuan,
Zheng Huzhi
Publication year - 2018
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201705980
Subject(s) - fluorescein , visible spectrum , detection limit , chemistry , analyte , fluorescence , photochemistry , naked eye , carboxylesterase , combinatorial chemistry , enzyme , chromatography , materials science , optoelectronics , optics , organic chemistry , physics
Abstract We have found that fluorescein possesses high visible‐light‐induced oxidase mimetic activity and could transform colorless 3,3′,5,5′‐tetramethylbenzidine (TMB) into blue oxidized TMB (oxTMB) without unstable and destructive H 2 O 2 under visible‐light illumination. Instead, fluorescein uses oxygen as a mild and green electron acceptor, and its activity can be easily controlled by the switching “on/off” of visible light. In addition, the visible‐light‐induced catalytic mechanism was elucidated in detail and, as the main reactive species h + and O 2 .− accounted for TMB oxidation. Based on the fact that fluorescein diacetate (FDA) possessed no activity and generated active fluorescein in situ in the presence of carboxylesterase (CaE), a signal‐amplified sensing platform through a cascade reaction for CaE detection was constructed. Our proposed sensing system displayed excellent analytical performance for the detection of CaE in a wide linear range from 0.040 to 20 U L −1 with a low detection limit of 0.013 U L −1 . This work not only changes the conventional concept that fluorescein is generally considered to be photocatalytically inert, but also provides a novel sensing strategy by tailoring the enzyme mimetic activity of fluorescein derivatives with analyte.