▎ 摘　　要

NOVELTY - Method for preparing prostate specific antigen (PSA) sensor involves (a) polishing glassy carbon electrode using aluminum oxide powder, and washing the electrode using ultrapure water, (b) adding gold (Au)-tin oxide(SnO2)-graphene sheet (GS) solution, and washing electrode, (c) adding PSA capture antibody Ab1 solution and bovine serum albumin solution, and washing the electrode, (d) adding PSA antigen Ag solutions in different concentrations, and drying the electrode, and (e) adding antibody Ab2-Ag-Cys-Au solution, incubating and drying the electrode. USE - The method is useful for preparing PSA sensor, which is used as immunosensor for detecting tumor marker PSA (all claimed) e.g. prostrate cancer marker. ADVANTAGE - The prepared PSA sensor has high specificity and sensitivity for detecting tumor marker PSA e.g. prostrate cancer marker. DETAILED DESCRIPTION - Method for preparing prostate specific antigen (PSA) sensor involves (a) polishing glassy carbon electrode having diameter of 3-5 mm using aluminum oxide powder, and washing the electrode using ultrapure water, (b) dropwise adding 6 mu l of 1-4 mg/l of gold (Au)-tin oxide(SnO2)-graphene sheet (GS) solution on surface of the electrode, drying the electrode at room temperature, washing electrode with ultrapure water, again drying the electrode, (c) adding 6 mu l of 8-12 g/ml of PSA capture antibody Ab1 solution, drying the electrode at 4 degrees C in a refrigerator, dropwise adding 3 mu l of 1-3 mg/ml bovine serum albumin solution for blocking non-specific sites on the surface of electrode, washing the electrode, again drying the electrode at 4 degrees C in a refrigerator, (d) dropwise adding 6 mu l of PSA antigen Ag solutions in different concentrations of 10 fg/ml-50 ng/ml, drying the electrode at room temperature, washing electrode using ultrapure water, again drying the electrode at 4 degrees C in a refrigerator, and (e) adding 6 mu l of 1-3 mg/ml antibody Ab2-Ag-Cys-Au solution, incubating the electrode, and drying the electrode at 4 degrees C in a refrigerator. An INDEPENDENT CLAIM is included for use of immunosensor for detecting tumor marker PSA, which involves detecting tumor markers PSA by performing chronoamperometry at -0.4 V for 400 seconds in electrochemical workstation using 3-electrode system, where the 3-electrode system comprises saturated calomel electrode as reference electrode, platinum wire electrode as auxiliary electrode and PSA sensor as working electrode, adding 10 mo of 50 mmol/l phosphate buffer solution having pH of 5.1-8.6, and 10 mu l of 5 mol/l hydrogen peroxide solution at a interval of 50 seconds and recording changes.