A Label-Free Aptasensor for the Detection of Sulfaquinoxaline Using AuNPs and Aptamer in Water Environment

Sulfaquinoxaline (SQX) is widely utilized in aquaculture and animal husbandry due to its broad antimicrobial spectrum and low cost. However, it is difficult to degrade, and there are relevant residues in the aquatic environment, which could be harmful to both the ecological environment and human health. As a new recognition molecule, the aptamer can be recognized with SQX with high affinity and specificity, and the aptamer is no longer adsorbed to AuNPs after binding to SQX, which weakens the catalytic effect of AuNPs. Consequently, an aptasensor for the detection of SQX was successfully developed. This aptasensor exhibits a linear range of 40–640 ng/mL, with a detection limit of 36.95 ng/mL, demonstrating both sensitivity and selectivity. The recoveries of this aptasensor in water samples ranged from 90 to 109.9%, which was quite in line with high-performance liquid chromatography. These findings suggest that the aptasensor is a valuable tool for detecting SQX in aqueous environmental samples.