A 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 at point-of-care settings. However, most MN-based diagnostic approaches require complicated fabrication processes or post-processing of the extracted ISF. Here we show in-situ and on-needle measurement of target analytes by integrating hydrogel microneedles (HMN) with aptamer probes as the target recognition elements. Fluorescently tagged aptamer probes are chemically attached to the hydrogel matrix while a crosslinked patch is formed. We use the assay for specific and sensitive quantification of glucose concentrations in an animal model of diabetes to track hypoglycemia, euglycemia, and hyperglycemia conditions. The assay can track the rising and falling concentrations of glucose and the extracted measurements closely match those from the gold standard techniques. The assay enables rapid and reagentless target detection and can be readily modified to measure other target analytes in vivo. Our system has the potential to improve the quality of life of patients who are in need of close monitoring of biomarkers of health and disease.

Opportunities and challenges in the diagnostic utility of dermal interstitial fluid

“…Another finding from this method is that cycles of repeated pressure and relaxation reduce the ISF time-lag when measuring rapidly changing blood glucose levels 55 . An emerging variation of the needle-based method uses receptor-coated microneedle patches to bind target analytes in situ, followed by patch removal and ex vivo analysis without the need to collect substantial fluid volume 67,68 (Table 1, row 'Capture needles').…”

“…This enabled the capture of post-immunization antibodies and of IL-6 at femtomolar concentrations in the ISF of mice 67 . A similar aptamer-based approach was used to monitor glucose levels in rats 68 . Still, owing to the limited data available, it remains unclear which design is better from a practical perspective if the goal is to sense a disease state: redundant (multiple) microneedle perforations and sensors in the upper dermis, or a single and fully adequate sensor insertion (as with current CGM devices).…”

3D-Printed Microneedles for Point-of-Care Biosensing Applications

“…Additionally, modifying MNAs with specific bio-recognition elements such as aptamer can dramatically elevate the performance of the MNAs-based sensing platform. For example, hydrogel MNs were modified with a fluorescent-labeled aptamer probe for detection of glucose in a model animal, with minimum invasiveness, great specificity, and sensitivity [ 13 ]. Furthermore, another study presented a MN-supported electrochemical, aptamer-based sensor for continuous drug monitoring [ 14 ].…”

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

“…Transdermal biosensing can bring us one step closer to personalized and precision medicine as it enables tracking of patient health conditions in a non- or minimally invasive manner. − Transdermal biosensors analyze interstitial fluid (ISF), the fluid which is present in the lowermost skin layer of the dermis, for biomarker measurements. − Compared to other body fluids, ISF has the most similar molecular composition to blood plasma, in addition to possessing other unique features including biomarkers of medical relevance. , Microneedle (MN)-based techniques have been introduced as a pain-free, minimally invasive, and easy-to-use ISF sampling approach with the potential of integrating diagnostics. − MNs with a needle length less than 1000 μm enable efficient skin penetration and ISF extraction. , Different types of MNs implement various strategies to obtain ISF, for example, hollow MNs operate based on negative pressure, , porous MNs use capillary force, , and the most recent one, hydrogel-based MNs (HMNs), employ material absorption property. , Compared to other MNs, HMNs possess several advantages, including increased and rapid ISF extraction, high biocompatibility, lower fabrication cost, higher production yield, and, most importantly, ease of insertion and removal without causing skin damage. ,,,, …”