Synthetic antibodies for methamphetamine analysis: Design of high affinity aptamers and their use in electrochemical biosensors

An aptamer-based electrochemical biosensor was designed and fabricated for methamphetamine (METH) analysis. Several aptamer sequences developed by the GO-SELEX method were immobilized onto gold electrodes (GE) via gold-thiol affinity. Surface characterizations were performed by electrochemical methods including cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectrometry (EIS). GE/Apta-4/METH aptasensor was selected for further studies since the best results were obtained with the Apta-4 sequence in terms of analytical parameters. Accordingly, it exhibited good selectivity for METH analysis with a wide linear range of 0.1–50 ng/mL and a low limit of detection (LOD) which was found to be 0.467 ng/mL. The proposed aptasensor platform displayed good selectivity for the detection of METH in synthetic urine samples spiked with METH.