A four-channel paper microfluidic device with gold nanoparticles and aptamers for seized drugs.

In this note we describe a four-channel paper microfluidic device (μPAD) that utilizes gold nanoparticles (AuNPs) as colorimetric sensors and specifically tailored aptamers to capture a set of targeted drugs, including cocaine, codeine and methamphetamine. The design utilizes salt-induced aggregation of AuNPs to produce a color change that indicates the presence of target analytes. In the absence of the targets, the aptamers bind to AuNPs, preventing aggregation. This μPAD was developed by optimizing the concentrations of aggregating agents, AuNPs and aptamers. The resultant device is sensitive and specific, producing a positive result upon detection of the target analyte.