Reagentless Amperometric Immunosensor Based on Human Immunodeficiency Virus Diagnosis Marker Glycoprotein 160 Antibody Coated Gold-Magnetic Particles Modified Electrode
Abstract A novel amperometric immunosensor is investigated for human immunodeficiency virus (HIV) glycoprotein 160 (gp160) based on nano-Fe 3 O 4 (core)/Au (shell)/chitosan composite film as immobilization matrix. First, the complex [Cu(bpy) 2 (H 2 O)] 2 ·(C 6 H 8 O 4 ) 2 (ClO 4 ) 4 (CuL) was prepared and adsorbed on the surface of glass carbon electrode (GCE), then nano-Fe 3 O 4 (core)/Au (shell)/chitosan composite film was modified on the surface of GCE|CuL, and HIV gp160 antibody was furthermore immobilized on the surface to form one gp160 immunosensor (GCE|CuL/nano-Fe 3 O 4 (core)/Au (shell)/chit/anti gp160). CuL can be used as an electron transfer mediator for catalytic activity detection of H 2 O 2 . After the immunosensor is incubated with HIV gp160 solution at 37 °C for 30 min, the electron transfer access of CuL to H 2 O 2 is partly inhibited, which leads to a linear decrease of the catalytic efficiency to H 2 O 2 by the oxidation of immobilized CuL by H 2 O 2 at −300 mV in PBS at pH 7.0. Under the optimal conditions, the linear range of gp160 by the immunosensor is from 1 to 400 ng ml −1 , and the detection limit is 0.5 ng ml −1 at three times noise. The immunosensor shows more sensitivity and accuracy than the immunosensor only modified by gp160 antibody coated nano-Au/chitosan film. This method simplifies the detection system without adding electron transfer media to solution and shortens the analytical time with one-step immunoassay, thus it would be valuable for clinical immunoassay for HIV gp160 in serums of patients with AIDs.