MOFs-on-MOFs modified wearable electrochemical microneedle array for uric acid detection

Conventional UA detection relies on invasive blood or urine tests, limiting convenience and real-time monitoring. In this study, we have designed a novel microneedle array-based wearable electrochemical sensor to detect UA in skin interstitial fluid (ISF), which consists of a bi-metal-organic framework (bi-MOF) modified screen-printed electrode (SPE) and 3D-printed hollow microneedle array patch (HMNsAP). To this end, a "MOFs on MOFs" strategy was applied by combining HKUST-1 and Eu-MOF nanocomposites on an SPE, enhancing electrode surface area, electrode material porosity, and electron transfer efficiency. The HMNsAP was equipped with a microvalve and connected to a vacuum tube to facilitate efficient ISF extraction while preventing backflow to mitigate biosafety risk. The sensor showed outstanding analytical performance, with a low limit of detection of 20 nM and high recovery rates ranging from 98.6% to 100.4% across various UA concentrations in ex-vivo rat skin tests, along with strong selectivity and reproducibility, indicated by a relative standard deviation (RSD = 1.68%). These findings underscore the synergistic advantages of combining advanced MOF materials with an innovative microneedle system for precise UA monitoring in ISF, enhancing its role in personalized diagnostics and beyond.