A molecularly imprinted electrochemical microneedle sensor for multiplexed metabolites detection in human sweat

This article demonstrates an array of inexpensive molecularly imprinted microneedle platforms for the multi-plexed electrochemical detection of pH, epinephrine, dopamine, and lactate biomarkers in human sweat. The multiplexed sensors were fabricated via layer-by-layer (LbL) assembly on a polydimethylsiloxane (PDMS) microneedle platform coated with a conductive PDMS/carbon nanotube (CNT)/cellulose nanocrystal (CNC) composite (PDMS/CNT/CNC@PDMS). The pH sensor was comprised of a pH-responsive polyaniline (PANI)/ CNT/CNC/silver nanoparticle (AgNP) composite layer. The epinephrine, dopamine, and lactate sensors consisted of an additional epinephrine, dopamine, or lactate-imprinted PANI-co-3-aminophenylboronic acid (PBA)/gold nanoparticle (AuNP) layer atop the PANI/CNT/CNC/AgNP composite layer. Each sensor rapidly (similar to 2 min) and selectively responded to their target analytes, with excellent precision between scans. The limits of detection (LOD) for the epinephrine, dopamine, and lactate sensors were 0.0007 +/- 0.0002 mu M, 2.11 +/- 0.05 nM, and 0.07 +/- 0.07 mM, respectively. The pH sensor accurately responded to a pH range of 4.25-10. The applicability of the sensor platforms were successfully verified through quantification of pH, epinephrine, dopamine, and lactate in a human sweat sample, showing promise for use as a wearable, point of need (PON) sensor for sweat analytics.