Gold microneedles fabricated by casting of gold ink used for urea sensing

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 mu M, with a calculated limit of detection of 2.8 mu M and sensitivity of 31 nA/mM. The results reveal that these MN-based biosensors may underpin the development of wearable real-time monitoring devices. (C) 2019 Elsevier B.V. All rights reserved.