Aptamer-based electrochemical sensor for picomolar level tetracycline determination in wastewater

The widespread use of antibiotics, especially tetracycline, has contributed to the emergence of a global crisis of antibiotic resistance. In response to this threat, the development of precise and reliable sensors for detecting tetracycline in environmental sources is crucial. This study reports the development of an electrochemical aptasensor that rapidly and selectively detects and determines the amount of tetracycline in wastewater. Immobilizing a thiol-ended ssDNA onto a gold screen-printed electrode shows the interaction of tetracycline with aptamer, which was examined by cyclic voltammetry (CV) and square wave voltammetry (SWV) using ferro-ferri redox couple (pH 7.4) at room temperature. The developed aptasensor exhibits a wide linear range of 0.01 pM to 104 nM, with a limit of detection (LOD) of 0.002 pM. Excellent selectivity towards tetracycline is demonstrated by the constructed electrochemical sensor, which exhibits negligible change in response to interfering antibiotics such as doxycycline and chloramphenicol. Furthermore, the suggested aptasensor was effectively used to analyze tetracycline levels in wastewater samples, with recovery rates ranging from 100.96% to 110%. The developed aptasensor demonstrated adequate repeatability and stability with a relative standard deviation (RSD) of less than 2.88%. A molecular docking analysis demonstrated a good interaction between the aptamer and tetracycline, characterized by several hydrogen bonds, with the most stable configuration exhibiting the lowest binding energy of -8.86 kcal/mol. The ease of fabrication, rapid analysis time, and miniaturized system make apt/AuSPE suitable for environmental monitoring and public health protection.