Recent Advances in Non-Enzymatic Glucose Sensors Based on Metal and Metal Oxide Nanostructures for Diabetes Management- A Review

There is an undeniable growing number of diabetes cases worldwide that have received widespread global attention by many pharmaceutical and clinical industries to develop better functioning glucose sensing devices. This has called for an unprecedented demand to develop highly efficient, stable, selective, and sensitive non-enzymatic glucose sensors (NEGS). Interestingly, many novel materials have shown the promising potential of directly detecting glucose in the blood and fluids. This review exclusively encompasses the electrochemical detection of glucose and its mechanism based on various metal-based materials such as cobalt (Co), nickel (Ni), zinc (Zn), copper (Cu), iron (Fe), manganese (Mn), titanium (Ti), iridium (Ir), and rhodium (Rh). Multiple aspects of these metals and their oxides were explored vis-à-vis their performance in glucose detection. The direct glucose oxidation via metallic redox centres is explained by the chemisorption model and the incipient hydrous oxide/adatom mediator (IHOAM) model. The glucose electrooxidation reactions on the electrode surface were elucidated by equations. Furthermore, it was explored that an effective detection of glucose depends on the aspect ratio, surface morphology, active sites, structures, and catalytic activity of nanomaterials, which plays an indispensable role in designing efficient NEGS. The challenges and possible solutions for advancing NEGS have been summarized.

Electrocatalytic Glucose Oxidation at Coral-Like Pd/C3N4-C Nanocomposites in Alkaline Media

Porous coral-like Pd/C3N4-C nanocomposites are fabricated by a simple one-pot chemical reduction method. Their electrocatalytic performance is ~50% higher than a carbon-loaded palladium electrocatalyst (Pd/C) in alkaline media. This confirms that the glucose electrooxidation and sensing performance of a Pd/C can be improved by the synergy of graphitic carbon nitride (C3N4), though C3N4 exhibits poor electrical conductivity. Compared to Pd/C, the size of Pd nanoparticles in Pd/C3N4-C decreases. As a result, the activity of Pd/C3N4-C is enhanced due to the higher dispersion and the synergistic effect. Pd/C3N4-C presents a rapid response and high sensitivity to glucose. The sensitivity for glucose sensing at Pd/C3N4-C is 3.3 times that of at Pd/C in the range of 0.001–10 mM. In the lower range of 0.001–1 mM, the sensitivity at Pd/C3N4-C is ~10 times greater than Pd/C.