A disposable amperometric immunosensor for alpha-1-fetoprotein based on enzyme-labeled antibody/chitosan-membrane-modified screen-printed carbon electrode.
A screen-printed three-electrode system is fabricated to prepare a novel disposable screen-printed immunosensor for rapid determination of alpha-1-fetoprotein (AFP) in human serum. The immunosensor is prepared by entrapping horseradish peroxidase (HRP)-labeled AFP antibody in chitosan membrane to modify the screen-printed carbon electrode. The membrane is characterized with scanning electron microscope and electrochemical methods. After the immunosensor is incubated with AFP at 30 degrees C for 35 min, the access of the active center of HRP catalyzing the oxidation reaction of thionine by H(2)O(2) is partly inhibited. In presence of 1.2 mM thionine and 6 mM H(2)O(2), the electrocatalytic current decreases linearly in two concentration ranges of AFP from 0 to 20 and from 20 to 150 ng/mL with a detection limit of 0.74 ng/mL. The immunosensor shows an acceptable accuracy compared with those obtained from immunoradiometric assays. The interassay coefficients of variation are 6.6 and 4.2% at 10 and 100 ng/mL, respectively. The storage stability is acceptable in pH 7.0 phosphate buffer solution at 4 degrees C for more than 10 days. The proposed method can detect the AFP through one-step immunoassay and would be valuable for clinical immunoassay.
Yu
Hua
H
State Key Laboratory of Coordination Chemistry, Department of Chemistry, Institute of Chemical Biology, Nanjing University, Nanjing 210093, People's Republic of China.
Yan
Feng
F
Dai
Zong
Z
Ju
Huangxian
H
D000906:Antibodies / Q000737:chemistry; D015374:Biosensing Techniques / Q000379:methods*; D048271:Chitosan / Q000737:chemistry; D004563:Electrochemistry; D004566:Electrodes; D006735:Horseradish Peroxidase / Q000737:chemistry; D006801:Humans; D006861:Hydrogen Peroxide / Q000737:chemistry; D007124:Immunoenzyme Techniques / Q000379:methods*; D008567:Membranes, Artificial; D010640:Phenothiazines / Q000737:chemistry; D012680:Sensitivity and Specificity; D000509:alpha-Fetoproteins / Q000032:analysis*
D000906:Antibodies; D008567:Membranes, Artificial; D010640:Phenothiazines; D000509:alpha-Fetoproteins; D048271:Chitosan; D006861:Hydrogen Peroxide; D006735:Horseradish Peroxidase; C009469:thionine