A molecular recognition assisted colorimetric aptasensor for tetracycline

Based on the study of intrinsic conformational structure-dependent molecular recognition between tetracycline (TC) and anti-TC aptamers, herein, we focus on the classic gold nanoparticle (AuNPs)-based colorimetric aptasensor. We adopt a 40 mer T-rich aptamer with considerations of stand length, primary sequence, and conformational structure. A computational analysis was applied to further decipher the molecular binding property among the AuNPs, aptamer, and TC. The short length of the aptamer assisted easy adsorption of the aptamer onto the surface of AuNPs. The rich T bases with less affinity onto the surface of AuNPs contributed to the sensitivity of the biosensor. The computational analysis revealed that the binding sites on the 40 mer aptamer distributed closely, and the aptamer had a flexible conformational structure to be adsorbed onto or desorbed from the surface of AuNPs. After detailed optimization, we developed a label-free colorimetric aptasensor which provided both visual and spectrographic quantitation for TC detection in a honey sample with high specificity and a limit of detection (LOD) of 12.4 ng mL(-1). The present assay can be developed as a simple and efficient method for basic on-site screening for TC residue in honey products, both visually and quantitatively. Moreover, the present study proves the concept for TC aptasensor development with a successful prediction practice and may lay the foundation for the development of other aptasensors.