A Hydrogel Microneedle-Assisted Assay Integrating Aptamer Probes and Fluorescence Detection for Reagentless Biomarker Quantification

Abstract

Analyzing interstitial fluid (ISF) via microneedle devices enables patient health monitoring in a minimally invasive manner and at point-of-care settings. However, most of the MN-based diagnostic approaches require complicated fabrication processes or post-processing of the extracted ISF. Here we show on-needle measurement of target analytes by integrating hydrogel microneedles (HMN) with aptamer probes as the recognition elements. Fluorescently tagged aptamer probes are chemically attached to the hydrogel matrix using a simple and novel approach while a crosslinked patch is formed. For reagentless detection, we employ a strand displacement strategy where fluorophore-conjugated aptamers are hybridized with a DNA competitor strand conjugated to a quencher molecule. The assay is utilized for rapid (2 min) measurement of glucose, adenosine triphosphate, L-tyrosinamide, and thrombin ex vivo. Furthermore, the system enables the specific and sensitive quantification of rising and falling concentrations of glucose in an animal model of diabetes to track hypoglycemia, euglycemia, and hyperglycemia conditions. Our assay can be applied for rapid measurement of a diverse range of biomarkers, proteins or small molecules, introducing a generalizable platform for biomolecule quantification and has the potential to improve the quality of life of patients who are in need of close monitoring of biomarkers of health and disease.