A biosensor based on Fe 3 O 4 @MXene-Au nanocomposites with high peroxidase-like activity for colorimetric and smartphone-based detection of glucose.

A novel magnetic nanozyme Fe 3 O 4 @MXene-Au nanocomposite, which possessed higher peroxidase-like activity than that of Fe 3 O 4 nanoparticles and Fe 3 O 4 @MXene nanocomposites, was developed. The outstanding magnetic properties of the nanozyme endowed it with the ability of simple and rapid separation, achieving great recyclability. Based on Fe 3 O 4 @MXene-Au nanocomposites and glucose oxidase (Glu Ox), a highly selective colorimetric biosensor for glucose detection was developed. Fe 3 O 4 @MXene-Au nanocomposites can catalyze H 2 O 2 produced from glucose catalyzed by glucose oxidase to ·OH and oxidize colorless 3,3',5,5'-tetramethylbenzidine (TMB) to blue oxidized TMB (oxTMB) with a significant absorbance at 652 nm. The linear range of glucose was 0-1.4 mM under optimal conditions, with a limit of detection (LOD) of 0.11 mM. Glucose in human whole blood was successfully detected with satisfactory recoveries. Furthermore, a facile agarose hydrogel detection platform was designed. With smartphone software, glucose detection can be realized by the agarose hydrogel platform, demonstrating the potential in on-site and visual detection of glucose.