The preparation of label-free electrochemical immunosensor based on the Pt–Au alloy nanotube array for detection of human chorionic gonadotrophin

BackgroundHuman chorionic gonadotrophin (hCG) is a secretion of the placenta during pregnancy and gestational trophoblastic diseases. It increases as a consequence of abnormal placental invasion and placental immaturity. So, it is an important diagnostic marker of pregnancy and many diseases such as the hydatidiform mole, the choriocarcinoma, the orchic teratoma, etc.MethodsA novel amperometric immunosensor for determination of hCG was constructed by immobilizing hCG antibody on the Pt–Au alloy nanotube array which was produced by electrodepositing strategy using nanopore polycarbonate (PC) membrane at − 0.35 V. The vertically aligned Pt -Au alloy nanotube can be considered as an electrode and therefore each of the electrodes is similar to the nanoelectrode. The determination of hCG antigen was based on its obstruction to the electrocatalytic reduction of H2O2 by Pt–Au alloys after binding to the surface of electrode through immunoreactions.ResultsThe electrochemical behaviors were characterized with electrochemical impedance, cyclic voltammetry and chronoamperometry. Under the optimum condition, the current response of the immunosensor is in linear relationship with concentration of hCG ranging from 25 to 400 mIU/ml with a detection limit of 12 mIU/ml. Satisfactory results were obtained for determination of hCG in serum samples.ConclusionThis sensor displayed high selectivity, long-term stability and simplicity.