Engineered AuNPs/fMWCNT Nanocomposite Electrodes for High‐Sensitivity Methylglyoxal Sensing in Saliva and Sweat for Non‐Invasive Diabetes Monitoring

Elevated methylglyoxal (MG) levels contribute to diabetes-related complications through accelerated formation of advanced glycation end products, highlighting the need for sensitive, portable, and non-invasive monitoring strategies. Here, we report a gold-carbon nanohybrid electrochemical MG sensor integrated into a three-dimensional printed microfluidic platform for point-of-care analysis. The sensing interface is engineered by sequential electrodeposition of carboxyl-functionalized multi-walled carbon nanotubes (fMWCNT) and gold nanoparticles (AuNPs) onto a screen-printed carbon electrode (SPCE). The fMWCNT provide a high-surface-area scaffold for MG adsorption, while AuNPs enhance electroactive surface area and electron transfer. The AuNPs/fMWCNT/SPCE sensor exhibits quasi-reversible electrochemical behavior suitable for sensitive MG detection. The optimized sensor achieves reliable MG detection across a wide dynamic range (50 nM-100 µM), with limits of detection of 40 nM in aqueous media and 400 nM in artificial sweat. Accurate MG quantification in human saliva and sweat, with recoveries exceeding 97%, demonstrates robustness in complex biological matrices. This work demonstrates the potential of this electrochemical sensing system for future wearable biosensors and personalized diabetes monitoring.