Abstract: Objective: To select and use aptamers as molecular recognition elements to construct a biosensor based on the salt effect of gold nanoparticles for the rapid quantitative detection of staphylococcal enterotoxin A (SEA). Methods: Molecular docking and molecular dynamics simulation were used to truncate the SEA aptamer and predict the results. The simulation results were verified colorimetrically using gold nanoparticles. The optimal SEA aptamer was used as the molecular recognition element. The reaction system was optimized, the relationship between SEA mass concentration and absorbance ratio was explored, and the accuracy, precision and specificity of the developed method were evaluated. Results: An SEA aptamer with short sequence, high affinity, strong specificity and stability was selected. This method was characterized by low limit of detection (LOD) and satisfactory recoveries for spiked samples. Conclusion: Molecular simulation can effectively improve the screening efficiency of aptamers, and the proposed method can be used for rapid detection of SEA.

Key words: staphylococcal enterotoxin A; visualization; aptamer; truncation; molecular dynamics simulation; gold nanoparticles-based colorimetry