title: Enzyme-catalyzed silver deposition on irregular-shaped gold nanoparticles for electrochemical immunoassay of alpha-fetoprotein.
abstract: A new and disposable electrochemical immunosensor was designed for detection of alpha-fetoprotein (AFP), as a model analyte, with sensitivity enhancement based on enzyme-catalyzed silver deposition onto irregular-shaped gold nanoparticles (ISGNPs). The assay was carried out with a sandwich-type immunoassay protocol by using ISGNP-labeled anti-AFP antibodies conjugated with alkaline phosphatase (ALP-Ab(2)) as detection antibodies. The enzymatically catalytic deposition of silver on the electrode could be measured by stripping analysis in KCl solution due to the Ag/AgCl solid-state voltammetric process. Several labeling protocols including spherical gold nanoparticle-labeled ALP-Ab(2) and ISGNP-labeled ALP-Ab(2) were investigated for determination of AFP, and improved analytical properties were achieved with the ISGNP labeling. With the ISGNP labeling method, the effects of incubation time and incubation temperature for antigen-antibody reaction, and deposition time of silver on the current responses of the electrochemical immunosensors were also monitored. Under optimal conditions, the electrochemical immunosensor exhibited a wide dynamic range from 0.01 ng mL(-1) to 200 ng mL(-1) with a detection limit of 5.0 pg mL(-1) AFP. The immunosensor displayed a good stability and acceptable reproducibility and accuracy. No significant differences at the 95% confidence level were encountered in the analysis of 10 clinical serum samples between the developed immunoassay and the commercially available electrochemiluminescent method for determination of AFP.
authors.affiliation: Key Laboratory of Analysis and Detection for Food Safety (Ministry of Education & Fujian Province), Department of Chemistry, Fuzhou University, Fuzhou, PR China.
authors.forename: Wenqiang
authors.initials: W
authors.lastname: Lai
authors.forename: Dianping
authors.initials: D
authors.lastname: Tang
authors.forename: Xiaohua
authors.initials: X
authors.lastname: Que
authors.forename: Junyang
authors.initials: J
authors.lastname: Zhuang
authors.forename: Libing
authors.initials: L
authors.lastname: Fu
authors.forename: Guonan
authors.initials: G
authors.lastname: Chen
mesh_terms: D015415:Biomarkers; D002623:Chemistry Techniques, Analytical; D004563:Electrochemistry; D006046:Gold / Q000737:chemistry*; D006801:Humans; D007118:Immunoassay; D008855:Microscopy, Electron, Scanning; D008954:Models, Biological; D053758:Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D012834:Silver / Q000737:chemistry*; D000509:alpha-Fetoproteins / Q000032:analysis* / Q000737:chemistry
chemical_list: D015415:Biomarkers; D000509:alpha-Fetoproteins; D012834:Silver; D006046:Gold