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

ABSTRACT 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.