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Reagentless amperometric immunosensor for human chorionic gonadotrophin based on direct electrochemistry of horseradish peroxidase

2004; Elsevier BV; Volume: 21; Issue: 2 Linguagem: Inglês

10.1016/j.bios.2004.10.023

1873-4235

Jin Chen, Feng Yan, Zong Dai, Huangxian Ju,

Analytical Chemistry and Sensors

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.