Reagentless amperometric immunosensor for human chorionic gonadotrophin based on direct electrochemistry of horseradish peroxidase.
A novel amperometric immunosensor for determination of human serum chorionic gonadotrophin (HCG) was constructed by immobilization of HCG with titania sol-gel on a glassy carbon electrode and the direct electrochemistry of horseradish peroxidase (HRP) labeled to HCG antibody (HRP-anti-HCG). The morphologies of the HCG membrane were characterized to be chemically clean, porous and homogeneous. HRP-anti-HCG was functionally conjugated with the immobilized HCG after incubation in phosphate buffer (PBS) containing HRP-anti-HCG. A direct electron transfer of HRP with a rate constant of 1.35+/-0.40 s(-1) was observed at the HRP-anti-HCG-HCG/titania sol-gel membrane modified electrode in 0.1 M PBS pH 7.0. With a competitive mechanism the differential pulse voltammetric peak current of the immobilized HRP decreased linearly with an increasing HCG concentration from 2.5 to 12.5 mIU/ml in the incubation solution. The HCG immunosensor showed a detection limit of 1.4 mIU/ml, a good accuracy and acceptable precision and reproducibility with an intra-assay CV of 4.7% at 5.0 mIU/ml and an inter-assay precision of 8.1% obtained at 10 mIU/ml. The biosensor displayed a good stability in a storage period of 30 days.
Chen
Jin
J
Key Laboratory of Analytical Chemistry for Life Science, Education Ministry of China, Department of Chemistry, Nanjing University, Nanjing 210093, PR China.
Yan
Feng
F
Dai
Zong
Z
Ju
Huangxian
H
D015374:Biosensing Techniques / Q000295:instrumentation / Q000379:methods*; D006063:Chorionic Gonadotropin / Q000032:analysis* / Q000737:chemistry*; D020099:Coated Materials, Biocompatible / Q000032:analysis / Q000737:chemistry; D004563:Electrochemistry / Q000295:instrumentation* / Q000379:methods; D004800:Enzymes, Immobilized / Q000032:analysis / Q000737:chemistry; D006735:Horseradish Peroxidase / Q000032:analysis* / Q000737:chemistry*; D006801:Humans; D007118:Immunoassay / Q000295:instrumentation* / Q000379:methods; D007202:Indicators and Reagents; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
D006063:Chorionic Gonadotropin; D020099:Coated Materials, Biocompatible; D004800:Enzymes, Immobilized; D007202:Indicators and Reagents; D006735:Horseradish Peroxidase