Fe-MXene Nanozyme for Dual-Mode Colorimetric-SERS Sensing of Glucose With Mechanistic Insights Into Catalysis and...

The development of colorimetric and surface-enhanced Raman spectroscopy (SERS) dual-mode analytical platforms based on nonnoble-metal substrates is of considerable significance. However, the underlying mechanisms governing enzyme-mimetic catalysis and SERS enhancement in nonnoble-metal-based systems remain insufficiently understood. In this work, the Fe-MXene nanozyme was synthesized via a self-reduction strategy. Enzyme-like catalytic behavior and SERS enhancement performance were systematically elucidated by correlating the structural features of Fe-MXene with its catalytic efficiency and signal amplification capability, governed by the Fenton-like reactions and chemical enhancement mechanisms. On this basis, a dual-mode sensing platform was developed for glucose determination. Glucose was enzymatically oxidized by glucose oxidase to generate hydrogen peroxide, which triggered Fe-MXene-catalyzed oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) into a blue product, which exhibits distinct optical and Raman signatures. The sensor showed a linear response to glucose concentrations over 0.01-1.0 mM (colorimetric) and 0.01-0.8 mM (SERS), with detection limits of 14.2 µM (colorimetric) and 4.67 µM (SERS). Practical applicability was validated by glucose analysis in real samples, yielding satisfactory recoveries of 95.8%-106.5%. In addition, the Fe-MXene nanozyme exhibited excellent stability, signal uniformity, and reusability. This work presents a simple, cost-effective, and reliable dual-mode sensing strategy for glucose detection, highlighting its potential in advanced biosensing applications.