A Colorimetric Aptasensor for Detection of Tetracycline Based on Aggregation of Silver Nanoparticles

Tetracycline is a broad-spectrum antibiotic that can help control microbial infections in human and veterinary. Excessive use of tetracycline in veterinary medicine and animal feeds as antibiotics and growth promotors could lead to antibiotic residues in foodstuff. Tetracycline residues in the food chain can be responsible for undesirable side effects on human health and emergence of antibiotic resistance strains of bacteria in both veterinary and human. Therefore, there is an urgent need to develop a simple, rapid method for determination and quantification of antibiotic residues in animal-derived foods. In this study, a colorimetric aptasensor was designed for sensitive and fast detection of tetracycline based on aggregation of silver nanoparticles with a low cost. Our detection method exploits tetracycline-specific DNA aptamer as the recognition element of an optical sensor. In the absence of tetracycline, silver nanoparticles are still well—dispersed, stable against salt-induced aggregation. In the presence of tetracycline, DNA aptamers detach from the nanoparticle’s surface and bind to its target, leading to the aggregation of silver nanoparticles by salt and a noticeable color change from yellow to colorless. The presented aptasensor showed high sensitivity and selectivity toward tetracycline with a limit of detection as low as 100 nM with an analysis time of ~ 20 min. With regard to demonstrating sensitivity and specificity of the sensor, our sensing platform shows a great potential application in rapid detection of antibiotics in the field of biomedicine and food safety.