A Highly Sensitive Aptasensor for Sulfamethazine Detection Using an Enzyme-Linked Aptamer Assay

To detect sulfamethazine (SMZ) residues in edible animal products, a colorimetric aptasensor that is based on indirect competitive enzyme-linked aptamer assay (ELAA) is developed in this study. This ELAA uses SMZ-specific aptamers as recognition elements and enzyme as the signal readout element. The detection sensitivity and the specificity of the ELAA were investigated. Our results showed that the indirect competitive ELAA had a ultrasensitivity with a low detection limit of 0.05 ng mL(-1). In addition, the proposed indirect competitive ELAA exhibited an 50% inhibition concentration value of 0.64 ng mL(-1) for SMZ, and recoveries up to 80.5-92.3% with coefficients of variation of less than 10%. Furthermore, when the ELAA was used for incurred samples by detecting SMZ in chicken muscles, the results obtained by the ELAA methods showed a good agreement with those obtained by established TRFIA and HPLC methods. These results demonstrate that the proposed indirect competitive ELAA can be efficiently used with good accuracy and precision, providing a simple method for the detection of SMZ residue in animal tissues.