title: Digital multimeter-based immunosensing strategy for sensitive monitoring of biomarker by coupling an external capacitor with an enzymatic catalysis.
abstract: A new digital multimeter (DMM)-based immunosensing system was designed for quantitative monitoring of biomarker (prostate-specific antigen, PSA used in this case) by coupling with an external capacitor and an enzymatic catalytic reaction. The system consisted of a salt bridge-linked reaction cell and a capacitor/DMM-joined electronic circuit. A sandwich-type immunoreaction with target PSA between the immobilized primary antibody and glucose oxidase (GOx)-labeled detection antibody was initially carried out in one of the two half-cells. Accompanying the sandwiched immunocomplex, the conjugated GOx could catalyze the oxidation of glucose, simultaneously resulting in the conversion of [Fe(CN)6](3-) to [Fe(CN)6](4-). The difference in the concentrations of [Fe(CN)6](3-)/[Fe(CN)6](4-) in two half-cells automatically produced a voltage that was utilized to charge an external capacitor. With the closing circuit switch, the capacitor discharged through the DMM, which could provide a high instantaneous current. Under the optimal conditions, the resulting currents was indirectly proportional to the concentration of target PSA in the dynamic range of 0.05-7 ng mL(-1) with a detection limit (LOD) of 6 pg mL(-1). The reproducibility, precision, and selectivity were acceptable. In addition, the methodology was validated by analyzing 12 clinical serum specimens, receiving a good accordance with the referenced values for the detection of PSA.
authors.affiliation: Key Laboratory of Analysis and Detection for Food Safety (Ministry of Education & Fujian Province), Department of Chemistry, Fuzhou University, Fuzhou 350108, PR China. Electronic address: dianping.tang@fzu.edu.cn.
authors.forename: Dianping
authors.initials: D
authors.lastname: Tang
authors.affiliation: Key Laboratory of Analysis and Detection for Food Safety (Ministry of Education & Fujian Province), Department of Chemistry, Fuzhou University, Fuzhou 350108, PR China.
authors.forename: Bing
authors.initials: B
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Analysis and Detection for Food Safety (Ministry of Education & Fujian Province), Department of Chemistry, Fuzhou University, Fuzhou 350108, PR China.
authors.forename: Bingqian
authors.initials: B
authors.lastname: Liu
authors.affiliation: Key Laboratory of Analysis and Detection for Food Safety (Ministry of Education & Fujian Province), Department of Chemistry, Fuzhou University, Fuzhou 350108, PR China.
authors.forename: Guonan
authors.initials: G
authors.lastname: Chen
authors.affiliation: Institute of Environmental and Analytical Science, School of Chemistry and Chemical Engineering, Henan University, Kaifeng 475004, Henan, PR China. Electronic address: minghua.lu2009@hotmail.com.
authors.forename: Minghua
authors.initials: M
authors.lastname: Lu
mesh_terms: D015415:Biomarkers; D014408:Biomarkers, Tumor / Q000097:blood / Q000276:immunology; D015374:Biosensing Techniques / Q000295:instrumentation; D002384:Catalysis; D003217:Conductometry / Q000295:instrumentation*; D025802:Electric Capacitance; D004581:Electronics / Q000295:instrumentation; D004797:Enzyme-Linked Immunosorbent Assay / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005949:Glucose Oxidase / Q000737:chemistry* / Q000276:immunology; D006801:Humans; D008297:Male; D017430:Prostate-Specific Antigen / Q000097:blood*; D011471:Prostatic Neoplasms / Q000097:blood* / Q000175:diagnosis / Q000276:immunology; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation*
chemical_list: D015415:Biomarkers; D014408:Biomarkers, Tumor; D005949:Glucose Oxidase; D017430:Prostate-Specific Antigen
keywords: Digital multimeter; Enzyme immunoassay; Glucose oxidase; Prostate-specific antigen