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

Abstract

Analyzing interstitial fluid (ISF) via microneedle (MN) devices enables patient health monitoring in a minimally invasive manner and in point-of-care settings. However, most MN-based diagnostic approaches require complicated fabrication processes and postprocessing of the extracted ISF or are limited to detection of electrochemically active biomarkers. Here, we show on-needle measurement of target analytes by integrating hydrogel microneedles 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 cross-linked 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 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.

Recent Advances, Opportunities, and Challenges in Developing Nucleic Acid Integrated Wearable Biosensors for Expanding the Capabilities of Wearable Technologies in Health Monitoring

“…A colorimetric readout was observed upon detection. A recent study uses optical fluorescence intensities generated by the attachment of a particular biomarker to the aptamer-quencher complex to assess interstitial fluids utilizing aptamer-immobilized hydrogel microneedle patches [ 59 ]. To fabricate the microneedle patches, a mixture of methacrylated hyaluronic acid (MeHA), photoinitiator, and N,N′-methylenebisacrylamide (MBA) was prepared in buffer solution and applied to a negative PDMS mold.…”

“…To create the base of the patch, another layer of MeHA is added on top. However, the mold needed to be then washed to remove unbound aptamers and exposed to ultraviolet light for 5 min [ 59 ]. Microneedle-based wearable devices are new avenues for integrating nucleic acid-based assays.…”

“…Continuous measurement can be achieved by using a linker that prevents complete removal of the quencher-conjugated DNA from the aptamer upon target binding. Miniaturization of optical detecting strategies would also be an improvement for this device [ 59 ]. Another study developed a body heat-activated wearable bandage sensor for the detection of nucleic acid fragments of the zika virus by combining flexible microfluidic technology and RPA [ 30 ].…”

3D Printed Hydrogel Microneedle Arrays for Interstitial Fluid Biomarker Extraction and Colorimetric Detection

“…In addition, some biomarkers available in ISF are not available in blood plasma [ 17 ]. Transdermal biosensing allows for the non-invasive or minimally invasive continuous monitoring of patient health status, which can move us closer to personalized and precision medicine [ 10 , 18 , 19 ].…”

“…Straightforward and efficient methods for a complete analysis of interstitial fluid can result in game-changing advancements in diagnostic practices. These methods are not only painless and minimally invasive, but they are also appropriate for point-of-care and resource-constrained settings [ 18 ]. However, due to the stratum corneum (SC) barrier that is the skin’s outer layer, the ISF metabolites cannot easily permeate the skin surface for testing [ 21 ].…”