Miniaturized integrated electrochemical sensor using Ag@MoS2/graphene oxide aerogel for implantable non-enzymatic glucose monitoring

This study reports the successful synthesis of silver-decorated molybdenum disulfide/graphene oxide aerogels (Ag@MoS₂/GOA) via a combined hydrothermal and freeze-drying approach. This 3D aerogel-based nanocomposite offers a high surface area and porous framework, thereby significantly enhancing the diffusion of glucose molecules and their electrochemical interactions. Electrochemical non-enzymatic glucose sensors were subsequently fabricated by precisely depositing the nanocomposite onto a gold-coated tungsten (W-Au) microelectrode within a highly confined area. To further stabilize the active layer, electropolymerization of pyrrole was employed during the sensor's construction. This design not only enabled sensor miniaturization but also significantly increased its potential for implantable applications. Furthermore, an integrated reference electrode (IRE) based on Ag/AgCl was developed and seamlessly incorporated into the platform, thereby enhancing to the sensing system's compactness and self-sufficiency. Surface morphology analyses confirmed the successful and uniform formation of the nanocomposite layer on the electrode surface. Cyclic voltammetry (CV) experiments were conducted in both alkaline (1.0 M NaOH) and neutral (PBS) media, consistently revealing a significant enhancement in glucose oxidation under alkaline conditions. Amperometric measurements across a glucose concentration range of 1-18 mM demonstrated a remarkable sensitivity of 24.70 µA mM^-1 cm^-2, a low detection limit of 0.52 µM, a wide linear range, and excellent operational stability. The sensor further exhibited remarkable selectivity, excellent reproducibility, long-term durability, and a relatively fast response time (6-8 s). Collectively, these findings indicate that the Ag@MoS₂/GOA-based platform, effectively supported by an integrated reference electrode, represents a promising strategy for reliable and enzyme-free glucose detection in complex biological environments.