title: An organic-inorganic hybrid nanostructure-functionalized electrode for electrochemical immunoassay of biomarker by using magnetic bionanolabels.
abstract: A new electrochemical immunoassay of alpha-fetoprotein (AFP) was developed on an organic-inorganic hybrid nanostructure-functionalized carbon electrode by coupling with magnetic bionanolabels. Multi-walled carbon nanotubes (CNTs), single-stranded DNA, thionine and AFP were utilized for the construction of the immunosensor, while the core-shell Fe(3)O(4)-silver nanocomposites were employed for the label of horseradish peroxidase-anti-AFP conjugates (HRP-anti-AFP-AgFe). Electrochemical measurement toward AFP was carried out by using magnetic bionanolabels as traces and H(2)O(2) as enzyme substrate with a competitive-type immunoassay mode. Experimental results indicated that the immunosensors with carbon nanotubes and DNA exhibited better electrochemical responses than those of without carbon nanotubes or DNA. Under optimal conditions, the electrochemical immunosensor by using HRP-anti-AFP-AgFe as signal antibodies exhibited a linear range of 0.001-200 ng mL(-1) AFP with a low detection limit of 0.5 pg mL(-1) at 3s(B). Both intra- and inter-assay coefficients of variation were 7.3%, 9.4%, 8.7% and 10.2%, 7.8%, 9.4% toward 0.01, 30, 120 ng mL(-1) AFP, respectively. The specificity and stability of the electrochemical immunoassay were acceptable. In addition, the methodology was validated for 12 clinical serum specimens including 9 positive specimens and 3 normal specimens, receiving a good correlation with the results obtained from the referenced electrochemiluminescence assay.
authors.affiliation: Ministry of Education Key Laboratory of Analysis and Detection for Food Safety, Department of Chemistry, Fuzhou University, Fuzhou 350108, People's Republic of China.
authors.forename: Biling
authors.initials: B
authors.lastname: Su
authors.forename: Dianping
authors.initials: D
authors.lastname: Tang
authors.forename: Juan
authors.initials: J
authors.lastname: Tang
authors.forename: Qunfang
authors.initials: Q
authors.lastname: Li
authors.forename: Guonan
authors.initials: G
authors.lastname: Chen
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000032:analysis*; D002138:Calibration; D002417:Cattle; D004247:DNA; D058266:Dielectric Spectroscopy; D055664:Electrochemical Techniques / Q000379:methods*; D004566:Electrodes; D005290:Ferric Compounds / Q000737:chemistry; D006735:Horseradish Peroxidase / Q000378:metabolism; D006801:Humans; D006861:Hydrogen Peroxide / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007118:Immunoassay / Q000379:methods*; D007287:Inorganic Chemicals / Q000737:chemistry*; D008280:Magnetics / Q000379:methods*; D037742:Nanotubes, Carbon / Q000737:chemistry* / Q000648:ultrastructure; D009930:Organic Chemicals / Q000737:chemistry*; D010640:Phenothiazines / Q000737:chemistry; D012015:Reference Standards; D013056:Spectrophotometry, Ultraviolet; D013997:Time Factors; D000509:alpha-Fetoproteins / Q000032:analysis
chemical_list: D015415:Biomarkers; D005290:Ferric Compounds; D007287:Inorganic Chemicals; D037742:Nanotubes, Carbon; D009930:Organic Chemicals; D010640:Phenothiazines; D000509:alpha-Fetoproteins; C000499:ferric oxide; D004247:DNA; C427203:calf thymus DNA; D006861:Hydrogen Peroxide; D006735:Horseradish Peroxidase; C009469:thionine