A simple and label-free fluorescent aptasensor for detection of tobramycin: Appropriate for on-site antibiotic monitoring

Abstract

Herein a simple fluorescent aptasensor is introduced to quantitatively monitor tobramycin (TOB) antibiotic by using the inherent hairpin structure of TOB aptamer and SYBR Green I (SGI) dye, as the biorecognition element and signal reporter, respectively. In the presence of TOB, the preferential binding of the aptamer towards its target induces the conformational change of the aptamer from hairpin-like to a single string structure. Hence, the SGI intercalation is reduced, decreasing the fluorescent intensity. Under the effect of experimental conditions, there was a wide linear relationship between the relative fluorescence emission and TOB concentration in the range of 0.1–6 µM. Besides, the aptasensor could detect TOB with the detection limit as low as 0.063 µM. The developed aptasensor was utilized to determine TOB in human serum and milk samples with the detection limits of 0.043 and 0.034 µM, respectively. The label-free aptasensor with the main features of feasibility, simplicity and high sensitivity holds the superior potential to develop a low-cost sensing method for human diagnostics, food control, and environmental monitoring. The designed aptasensor can be efficiently applied by non-specialist consumers for on-site monitoring of the diverse targets by substituting their specific aptamers.