A wearable sensor integrating a MXene-PLL-GOx-modified electrode and a Janus nanofibrous membrane for electrochemical monitoring of sweat glucose

A cascade catalytic MXene-PLL-GOx/SPCE electrode is developed for non-invasive and sensitive sweat glucose monitoring. • PLL enables efficient GOx immobilization on MXene through charge regulation and covalent crosslinking. • A PU/PVA Janus nanofiber membrane enables directional sweat transport, while MXene-mediated H 2 O 2 conversion enhances glucose sensing. MXene is a two-dimensional transition metal carbide with large specific surface area, good conductivity, and outstanding biocompatibility, which can be integrated with electrochemical devices, significantly enhancing the sensing performance. Herein, we present a wearable electrochemical sensor based on MXene composites modified electrode and Janus nanofibrous membranes for active sweat collection and precise detection of sweat glucose. Poly- l -lysine (PLL) is highly positively charged because of the -NH 3 + groups, which acts as the crosslinker to bond MXene and glucose oxidase (GOx, containing -COO - groups) both negatively charged, forming a functional composite with high catalytic activity for glucose sensing. In this way, GOx was efficiently immobilized on the MXene nanosheets and then deposited on the screen-printed carbon electrode (SPCE). The intermediate H 2 O 2 from enzymatic glucose oxidation was catalytically decomposed by MXene into H 2 O and O 2 . The recycled O 2 further accelerated the enzymatic reaction on the SPCE. PU/PVA Janus nanofibrous membrane was prepared through electrospinning for active and effective sweat collection due to the unidirectional moisture conduction from its hydrophobic/hydrophilic side. The modified SPCE was integrated with the Janus nanofibrous membrane to fabricate a wearable sweat sensor, with the sensitivities of 16.70 μA mM −1  cm −2 for 0∼300 μM glucose levels, with a detection limit of 24.35 μM. The sensor also showed good stability, selectivity, and reproducibility, providing a new strategy for non-invasive sweat glucose monitoring. Download: Download high-res image (270KB) Download: Download full-size image