Current technology for blood glucose level monitoring is mainly based on the invasive finger‐prick extraction of a small drop of blood using a lancet and measured via a handheld glucometer, which is not conducive to continuous measurements. Interstitial fluid (ISF) is gaining attention as an alternative biofluid. Its biochemical composition is very similar to that of blood and it can be monitored in a continuous manner via minimally invasive methods that cause no pain and minimize any risk of infection. Herein, a microneedle array (MNA) based transdermal sensing system for the pain free monitoring of ISF glucose is presented. High‐density silicon microneedles (≈9500 microneedles cm−2) are used to prepare a three‐electrode patch for the electrochemical monitoring of glucose. The MNA glucose patch shows very good selectivity when tested in artificial ISF, with a sensitivity of 0.1622 µA mm−1 cm−2 and a detection limit of 0.66 mm. In vivo application of the microneedle array in mice shows that the ISF glucose concentrations obtained with the MNA sensor gave very good correlation with the blood glucose levels determined with a commercial glucometer. This microneedle‐based sensing system hence provides an alternative transdermal diagnostic tool to the invasive existing techniques.

Abstract Here we present the simple and effective fabrication method of an array of gold microneedles (AuMNs) via the casting of conductive gold ink. To demonstrate the potential of MN arrays as electrochemical biosensors we functionalized AuMNs with an epoxy- and ferrocene-functional polymeric mediator and covalently immobilised urease. The performance of the MN array biosensor for urea detection was assessed in artificial interstitial fluid and epidermal/skin mimic, both spiked with urea. The analytical performance of MN biosensor shows that urea is detected in the range of 50–2500 µM, with a calculated limit of detection of 2.8 µM and sensitivity of 31 nA/mM. The results reveal that these MN-based biosensors may underpin the development of wearable real-time monitoring devices.

The aim of this study was the electrochemical detection of the adenosine-3-phosphate degradation product, xanthine, using a new xanthine biosensor based on a hybrid bionanocomposite platform which has been successfully employed in the evaluation of meat freshness. In the design of the amperometric xanthine biosensor, chitosan–polypyrrole–gold nanoparticles fabricated by an in situ chemical synthesis method on a glassy carbon electrode surface was used to enhance electron transfer and to provide good enzyme affinity. Electrochemical studies were carried out by the modified electrode with immobilized xanthine oxidase on it, after which the biosensor was tested to ascertain the optimization parameters. The Biosensor exhibited a very good linear range of 1–200 μM, low detection limit of 0.25 μM, average response time of 8 seconds, and was not prone to significant interference from uric acid, ascorbic acid, glucose, and sodium benzoate. The resulting bio-nanocomposite xanthine biosensor was tested with fish, beef, and chicken real-sample measurements.