Design and performance of cocaine and adenosine detections using a PGM. a, Cocaine-induced release of immobilized DNA–invertase conjugates. b, Cocaine detection in buffer using the PGM. c, Cocaine detection in human serum and calf blood samples using the PGM. d, Adenosine-induced release of immobilized DNA–invertase conjugates. e, Adenosine detection using the PGM. f, Effects of active aptamers on the performance of the PGM in detecting adenosine and cocaine in the presence of 1 mM targets; −, with aptamer active site truncated; +, with no truncation. All error bars were obtained through the detection of three parallel samples.