Study of Aptamer-Based Lateral Flow Strip and Its Application for Qualitative Detection of Staphylococcus aureus

In this experiment, Staphylococcus aureus was selected as the model target, and a pair of aptamers were used as the recognition molecules. An aptamer-based lateral flow test strip (ABLF) was prepared for the qualitative detection of Staphylococcus aureus based on the sandwich-type model and principle of lateral flow chromato gram. Several crucial parameters were investigated, including the NaCl concentrations, aptamer concentrations, the loaded amounts of gold nanoparticle-aptamer conjugates and capture probe to obtain the best preparation conditions for ABLF. The sensitivity and specificity of the ABLF were tested under optimized conditions. Finally, the ABLF approach was applied for qualitative detection of Staphylococcus aureu in 116 food samples, and was validated using sandard method (GB 4789.10-2016). The results showed that the optimal conditions for preparing ABLF were as follows: NaCl concentration 80 mmol/L, aptamer concentration 1 µmol/L, dilution volume ratio of gold nanoparticles-aptamer 1:2, capture probe concentration 25 μmol/L. Under the optimal experimental conditions, the visual limit of detection of the strip for Staphylococcus aureus were 2×10³ CFU/mL. The assay can be completed within 5 min, and no significant cross-reactivity with other foodborne pathogens such as Salmonella typhimurium, Listeria monocytogenes, Escherichia coli, Bntorobater sakazakii, Shigella dysenteriae were observed. The test results obtained by the proposed method were found to be in consistency with those obtained from GB sandard method. The method developed was simple, rapid, accurate and inexpensive, which could be a potential screening tool for the qualitative detection of Staphylococcus aureus in food samples.