Abstract: 【Objective】 The aim of this experiment was to construct a colloidal gold immunochromatography for the rapid detection of Staphylococcus aureus.【Method】 The colloid gold was prepared and characterized, and then connected with aptamer, characterized and sprayed on the binding pad.The test strip was constructed with polyclonal antibody as the test line and the complementary sequence of aptamer as the control line.The test conditions of sample pad and binding pad treatment solution, sample dilution solution, suspension solution, T-line antibody concentration, and aptamer connection concentration were optimized to obtain the best conditions.At the same time, the sensitization effect of the test strip was studied, and the sensitivity and specificity of the test strip were tested under the best conditions.Finally, the artificial contaminated sample was prepared to evaluate the effect of the test strip in the actual sample detection.【Result】 The particle size of colloidal gold was about 20 nm, and the results showed that the colloidal gold was successfully connected to the aptamer.The optimal conditions for the sample pad, the binding pad and the sample diluent were SELEX buffer with different components, the resuspension with gold standard was HEPES resuspension, and the T-line antibody concentration was 2 mg/mL.The aptamer binding concentration was 1 μmol/L, and 40 mmol/L hydroxylamine was sensitized with 0.5% gold chloride aqueous solution, and the detection sensitivity was 1×10⁴ CFU/mL with good specificity.For artificially contaminated meat and milk samples, the sensitivity was 1×10⁵ CFU/mL.【Conclusion】 The test strip detection method for Staphylococcus aureus was established successfully, and had good specificity, which provided a theoretical basis for further exploring the application of nucleic acid aptamer in the detection of pathogenic bacteria.

Key words: aptamers; colloidal gold; Staphylococcus aureus; rapid detection