Diagnosis by simplicity: an aptachip for dopamine capture and accurate detection with a dual colorimetric and fluorometric system.

In this study, we aim to rapidly fabricate an aptachip with a dual colorimetric and fluorometric sensing strategy for easy dopamine (DA) detection with high sensitivity and selectivity. To construct an aptachip with high DA capture efficiency, molecular dynamics (MD) simulations were utilitized to predict the most stable configuration of the DA-binding aptamer (DBA) for DA recognition. The DA in the specimen would be specifically captured on the DBA-aptachip, then released from the DBA in alkaline solution to form DA-quinone (DAQ), thus leading to a color change (from colorless to brown) and inducing a dramatic decrease in the fluorescence intensity as a result of the photoinduced electron transfer (PET) for bovine serum albumin (BSA)-stabilized Au nanoclusters (BSA-Au NCs). The detection limit of DA is as low as 0.1 μg mL for the colorimetric system and 0.5 ng mL for the fluorometric system. In addition, this biosensing of DA is easy to implement for visual detection owing to the DA oxidation and fluorescence quenching by BSA-AuNCs in the presence of the alkaline solution. Both the colorimetric and fluorometric systems showed excellent selectivity toward DA over interfering substances. Furthermore, we demonstrated the application of the present approach to analysis of artificial cerebrospinal fluid (ACSF) and serum samples, suggesting that this system holds promise for diagnostics.