title: An ultrasensitive and universal photoelectrochemical immunoassay based on enzyme mimetics enhanced signal amplification.
abstract: An ultrasensitive photoelectrochemical (PEC) immunoassay based on signal amplification by enzyme mimetics was fabricated for the detection of mouse IgG (as a model protein). The PEC immunosensor was constructed by a layer-by-layer assembly of poly (diallyldimethylammonium chloride) (PDDA), CdS quantum dots (QDs), primary antibody (Ab1, polyclonal goat antimouse IgG), and the antigen (Ag, mouse IgG) on an indium-tin oxide (ITO) electrode. Then, the secondary antibody (Ab2, polyclonal goat antimouse IgG) combined to a bio-bar-coded Pt nanoparticle(NP)-G-quadruplex/hemin probe was used for signal amplification. The bio-bar-coded Pt NP-G-quadruplex/hemin probe could catalyze the oxidation of hydroquinone (HQ) using H2O2 as an oxidant, demonstrating its intrinsic enzyme-like activity. High sensitivity for the target Ag was achieved by using the bio-bar-coded probe as signal amplifier due to its high catalytic activity, a competitive nonproductive absorption of hemin and the steric hindrance caused by the polymeric oxidation products of HQ. For most important, the oxidation product of HQ acted as an efficient electron acceptor of the illuminated CdS QDs. The target Ag could be detected from 0.01pg/mL to 1.0ng/mL with a low detection limit of 6.0fg/mL. The as-obtained immunosensor exhibited high sensitivity, good stability and acceptable reproducibility. This method might be attractive for clinical and biomedical applications.
authors.affiliation: The Key Laboratory of Food Colloids and Biotechnology, Ministry of Education, School of Chemical and Material Engineering, Jiangnan University, Wuxi 214122, PR China; State Key Laboratory of Analytical Chemistry for Life Science, Nanjing University, Nanjing 210093, PR China. Electronic address: glwang@jiangnan.edu.cn.
authors.forename: Guang-Li
authors.initials: GL
authors.lastname: Wang
authors.affiliation: The Key Laboratory of Food Colloids and Biotechnology, Ministry of Education, School of Chemical and Material Engineering, Jiangnan University, Wuxi 214122, PR China.
authors.forename: Jun-Xian
authors.initials: JX
authors.lastname: Shu
authors.affiliation: The Key Laboratory of Food Colloids and Biotechnology, Ministry of Education, School of Chemical and Material Engineering, Jiangnan University, Wuxi 214122, PR China.
authors.forename: Yu-Ming
authors.initials: YM
authors.lastname: Dong
authors.affiliation: The Key Laboratory of Food Colloids and Biotechnology, Ministry of Education, School of Chemical and Material Engineering, Jiangnan University, Wuxi 214122, PR China.
authors.forename: Xiu-Ming
authors.initials: XM
authors.lastname: Wu
authors.affiliation: The Key Laboratory of Food Colloids and Biotechnology, Ministry of Education, School of Chemical and Material Engineering, Jiangnan University, Wuxi 214122, PR China.
authors.forename: Zai-Jun
authors.initials: ZJ
authors.lastname: Li
mesh_terms: D000818:Animals; D055910:Antibodies, Immobilized / Q000737:chemistry; D015374:Biosensing Techniques / Q000295:instrumentation; D019187:Cadmium Compounds / Q000737:chemistry; D055664:Electrochemical Techniques / Q000295:instrumentation*; D004566:Electrodes; D004867:Equipment Design; D054856:G-Quadruplexes; D006427:Hemin / Q000737:chemistry; D006801:Humans; D007118:Immunoassay / Q000295:instrumentation*; D007074:Immunoglobulin G / Q000032:analysis*; D057230:Limit of Detection; D008163:Luminescent Measurements / Q000295:instrumentation; D051379:Mice; D010984:Platinum / Q000737:chemistry*; D011095:Polyethylenes / Q000737:chemistry; D045663:Quantum Dots / Q000737:chemistry* / Q000648:ultrastructure; D000644:Quaternary Ammonium Compounds / Q000737:chemistry; D015203:Reproducibility of Results; D013440:Sulfides / Q000737:chemistry; D017971:Tin Compounds / Q000737:chemistry
chemical_list: D055910:Antibodies, Immobilized; D019187:Cadmium Compounds; D007074:Immunoglobulin G; D011095:Polyethylenes; D000644:Quaternary Ammonium Compounds; D013440:Sulfides; D017971:Tin Compounds; C034939:cadmium sulfide; C041004:poly-N,N-dimethyl-N,N-diallylammonium chloride; D010984:Platinum; C109984:indium tin oxide; D006427:Hemin
keywords: Bio-bar-coded Pt NP-G-quadruplex/hemin probe; CdS quantum dots; Enzyme mimetics; Photoelectrochemical immunoassay