title: Enzymatically biocatalytic precipitates amplified antibody-antigen interaction for super low level immunoassay: an investigation combined surface plasmon resonance with electrochemistry.
abstract: We demonstrated a simple and efficient strategy, which based on the enzymatically biocatalytic precipitates amplified antibody-antigen interaction, for improving the response signals of surface plasmon resonance (SPR) immunosensing. The antibody-antigen-alkaline phosphatase (AP) labeled secondary antibody sandwich were successfully prepared and characterized by SPR, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The SPR signal amplification was accomplished through probing resonance angle shift and Faradaic electron impedance of [Fe(CN)(6)](3-/4-) redox pair after the enzymatically biocatalytic products precipitating on the immunosensing electrode surface. As a result, the accumulation of the enzymatically biocatalytic precipitates leads to significantly resonance angle shift and increase of electron transfer impedance of [Fe(CN)(6)](3-/4-) probe. The precipitates-enhanced sandwich SPR immunoassay for mouse immunoglobulin G (m-IgG) can easily detect solution protein concentrations in the linear range of 0.02-40 ng mL(-1) and with a detection limit of 200 fg mL(-1), which is more than four-orders and 10 times better compared with the values using streptavidin-biotinylated protein complex and biotinylated HRP biocatalyzation amplification methods. Moreover, this method is generally applicable to other sandwich immunoassays and also can be expanded to monitor other antibody-antigen interaction for immunosensing detection at low concentrations.
authors.affiliation: Ministry of Education Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research, College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha, PR China. tanghao@hunnu.edu.cn
authors.forename: Hao
authors.initials: H
authors.lastname: Tang
authors.forename: Qiong
authors.initials: Q
authors.lastname: Wang
authors.forename: Qingji
authors.initials: Q
authors.lastname: Xie
authors.forename: Youyu
authors.initials: Y
authors.lastname: Zhang
authors.forename: Liang
authors.initials: L
authors.lastname: Tan
authors.forename: Shouzhuo
authors.initials: S
authors.lastname: Yao
mesh_terms: D000469:Alkaline Phosphatase; D000906:Antibodies; D000915:Antibody Affinity; D000941:Antigens; D002384:Catalysis; D004563:Electrochemistry; D007118:Immunoassay; D007159:Immunologic Tests; D020349:Surface Plasmon Resonance
chemical_list: D000906:Antibodies; D000941:Antigens; D000469:Alkaline Phosphatase