title: The preparation of label-free electrochemical immunosensor based on the Pt-Au alloy nanotube array for detection of human chorionic gonadotrophin.
abstract: BACKGROUND
  Human 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.
  
  
  METHODS
  A 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 H(2)O(2) by Pt-Au alloys after binding to the surface of electrode through immunoreactions.
  
  
  RESULTS
  The 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.
  
  
  CONCLUSIONS
  This sensor displayed high selectivity, long-term stability and simplicity.
authors.affiliation: College of Chemistry and Chemical Engineering, Yunnan Normal University, Kunming 650092, PR China.
authors.forename: Manlan
authors.initials: M
authors.lastname: Tao
authors.forename: Xiaofei
authors.initials: X
authors.lastname: Li
authors.forename: Zaisheng
authors.initials: Z
authors.lastname: Wu
authors.forename: Meng
authors.initials: M
authors.lastname: Wang
authors.forename: Mei
authors.initials: M
authors.lastname: Hua
authors.forename: Yunhui
authors.initials: Y
authors.lastname: Yang
mesh_terms: D000497:Alloys; D015374:Biosensing Techniques; D002138:Calibration; D006063:Chorionic Gonadotropin / Q000097:blood*; D055664:Electrochemical Techniques / Q000295:instrumentation*; D004566:Electrodes; D006046:Gold; D008855:Microscopy, Electron, Scanning; D043942:Nanotubes; D010984:Platinum; D015203:Reproducibility of Results
chemical_list: D000497:Alloys; D006063:Chorionic Gonadotropin; D010984:Platinum; D006046:Gold