In this work, we introduced an improved method for developing a robust and user-friendly point of care (POC) diagnostic device to monitor stress and depression biomarkers (cortisol and dopamine) in non-invasive biofluids (sweat, urine and saliva). A paper-based apata-sensor device with three channels is designed to detect the levels of stress biomarkers within 10 minutes by providing a red band in each channel. Color intensity in the test zone of each channel in the device indicates the target concentration in sample. Most POC biomarker monitoring assays are based on immunochemical reactions using antibody recognition. The use of aptamer- functionalized gold nanoparticles (AuNPs) as a colorimetric method of detection in strip biosensors are an attractive alternative to overcome the limitations of current methods: immunogenicity, complex laboratory techniques, time consuming and large sample volume. Each channel of the device developed by a unique design based on the size and concentration of the biomarkers and the type of the target biofluids.<br/>Two approaches; target induced structure switching and target-induced dissociation/displacement were incorporated for developing the biosensor. Non-thiolated cortisol aptamers conjugated to the AuNPs surface, via physical absorption, could provide a 0.1µg/dL visual limit of detection (LOD). Presence of the cortisol in sweat makes conformational changes of the aptamers on AuNPs surface and leads to dissociation of the aptamer from AuNPs surface. Immobilized cysteamine on device could capture the naked AuNPs and provide a red band in test line. The intensity of the red band in test zone has a direct relation with the target concentration in sweat, Fig. 1a.<br/>The channel for dopamine detection in urine designed based on aptamer (as a sensor probe) dissociation from the capture part. More target in sample makes more aptamers goes under conformational changes and leaves the capture part to do hybridization with the immobilized complementary probe in the test zone, Fig. 1b.

Developing aptamer-based biosensor for onsite detection of stress biomarkers in noninvasive biofluids

2019 Fall National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.