Development of a ssDNA aptamer for detection of residual benzylpenicillin

Antibiotics are useful for improving the living conditions of livestock. However, residual antibiotics induce several human diseases such as food-borne illness and infection of carbapenem-resistant Enterobacteriaceae (CRE). In this study, the identification of a benzylpenicillin-specific aptamer was selected by rGO-SELEX (reduced Graphene Oxide-Systematic Evolution of Ligands by EXponential enrichment). A random ssDNA library was incubated with rGO for adsorption and eluted with benzylpenicillin. As a result of the selection process, a DNA aptamer was found that specifically bound to benzylpenicillin with high binding affinity, K_d = 383.4 nM, and had a low limit of detection (LOD) of 9.2 nM. The characterization of the aptamer was performed through the fluorescence recovery signal from rGO surface. In addition, detection of benzylpenicillin was performed in pretreated milk samples, and its detection accuracy was shown to be 100± 10%. This represented that BBA1 was used for fluorescence aptasensor system in real sample. Furthermore, this benzylpenicillin binding aptamer showed high specificity against other antibiotics except for ampicillin. With these advantageous characteristics, we expect that this aptamer could be applied to an on-site detection system for residual benzylpenicillin.