title: Electrochemiluminescent quenching of quantum dots for ultrasensitive immunoassay through oxygen reduction catalyzed by nitrogen-doped graphene-supported hemin.
abstract: A hemin functionalized graphene sheet was prepared via the noncovalent assembly of hemin on nitrogen-doped graphene. The graphene sheet could act as an oxygen reduction catalyst to produce sensitive electrochemiluminescent (ECL) quenching of quantum dots (QDs) due to the annihilation of dissolved oxygen, the ECL coreactant, by its electrocatalytic reduction. With the use of the catalyst with high loading of hemin as a signal tag of the secondary antibody, a novel ultrasensitive immunoassay method for biomarker detection was proposed. In an air-saturated pH 8.0 buffer, the immunosensor constructed by a stepwise immobilization of bidentate-chelated CdTe QDs and capture antibody showed an intensive cathodic ECL irradiation, which could be scavenged upon the formation of the catalyst-bound sandwich immunocomplex. With the use of the carcinoembryonic antigen as a model analyte, the immunoassay method showed a linear range from 0.1 pg mL(-1) to 10 ng mL(-1) and a detection limit of 24 fg mL(-1). The immunosensor exhibited good stability, acceptable fabrication reproducibility, and practicability. The electrocatalytic reduction-based ECL quenching strategy provided a powerful avenue for the design of the ultrasensitive detection method, showing great promise for clinical application.
authors: State Key Laboratory of Analytical Chemistry for Life Science, Department of Chemistry, Nanjing University, Nanjing 210093, China.
authors: Shengyuan
authors: S
authors: Deng
authors: Jianping
authors: J
authors: Lei
authors: Yin
authors: Y
authors: Huang
authors: Yan
authors: Y
authors: Cheng
authors: Huangxian
authors: H
authors: Ju
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D002272:Carcinoembryonic Antigen / Q000097:blood* / Q000276:immunology; D002384:Catalysis; D004563:Electrochemistry; D006108:Graphite / Q000737:chemistry; D006427:Hemin / Q000737:chemistry*; D006801:Humans; D007118:Immunoassay; D007074:Immunoglobulin G / Q000276:immunology; D057230:Limit of Detection; D008163:Luminescent Measurements / Q000379:methods*; D049329:Nanostructures / Q000737:chemistry; D009584:Nitrogen / Q000737:chemistry; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry; D045663:Quantum Dots
chemical_list: D002272:Carcinoembryonic Antigen; D007074:Immunoglobulin G; D006427:Hemin; D006108:Graphite; D009584:Nitrogen; D010100:Oxygen