A reagentless amperometric immunosensor for human chorionic gonadotrophin based on a gold nanotube arrays electrode

Gold nanotubes array has been synthesized by direct electrodeposition with cyclic voltammetry utilizing anodic aluminum oxide template (AAO). The morphological characterizations of the gold nanotubes prepared with different electrodepositing time have been investigated by scanning electron microscopy (SEM). The results shows that as electrodepositing time increased, the inner diameter of gold nanotubes become smaller. An amperometric immunosensor for determination of human serum chorionic gonadotrophin (hCG) was constructed by immobilizing hCG antibody (anti-hCG) onto gold nanotubes array. The fabricated procedures and electrochemical behaviors of proteins on such an interface were characterized with electrochemical impedance, cyclic voltammetry and chronoamperometry. Effects of electrodepositing time of gold nanotubes on the amperometric response of experimental measurements and other experimental conditions such as pH, incubation time and temperature were studied and the optimal pH, incubation time and temperature were 6.9, 40 min, 33 °C, respectively. The resulting immunosensor offers an excellent amperometric response for hCG ranging from 0.1 to 100 mIU mL−1 and the detection limit of 0.08 mIU mL−1 with the correlation coefficient of 0.991. The immunosensor shows satisfactory regeneration, stability and selectivity. A satisfactory determination of hCG in serum samples can be obtained by this immunosensor.