An electrochemical aptasensor based on enzyme linked aptamer assay

► A simple and sensitive aptasensor for cocaine detection based on enzyme linked aptamer assay (ELAA) is developed. ► The detection limit down to 20 nM for cocaine has been achieved by thereaction of H2O2 and HQ catalyzed by HRP. ► The aptasensor shows the potential application in biological fluid. ► A new configuration for ELAA requiring only a single aptamer sequence can be generalized to detect different kinds of targets.