A label-free aptasensor for the sensitive and specific detection of cocaine using supramolecular aptamer fragments/target complex by electrochemical impedance spectroscopy

► A simple label-free aptasensor was developed by electrochemical impedance spectra. ► For the optimization, we designed and compared three different sensing interfaces. ► The sensor could detect as low as 100 nM cocaine without amplification or labeling. ► The aptasensor showed the potential application in biological fluid.