Nano-alloys for glucose detection and energy storage

– Devansh Sanjay Jhawar

Image: Gokul Raj

Most glucose sensors for measuring sugar levels use enzymes that catalyse glucose oxidation. However, these are expensive, sensitive to environmental factors like temperature and moisture, and cannot detect glucose below a certain level. Non-enzymatic methods are, therefore, increasingly becoming popular.

In a new study, scientists from the Materials Research Centre (MRC), IISc have tweaked High Entropy Nano Alloys (HENAs) – materials made by mixing five or more elements – to turn them into non-enzymatic glucose sensors. The team combined iron, cobalt, nickel, manganese, and chromium under conditions that prompted the metals to fuse into an alloy. Then, they crushed and heated the alloys in a tube furnace under nitrogen gas flow, which allowed the metals to form nano alloys encapsulated within Nitrogen-doped Carbon Nano Tubes (HENAs@NCNTs). Nitrogen doping increases conductivity by increasing charge carriers, and CNTs shield them from harsh environments.

The hybrid material showed superior thermal and chemical stability. It catalyses glucose oxidation in saliva to produce hydrogen peroxide, which on further oxidation generates electrons. These electrons send a signal in the form of a current proportional to the glucose concentration. The sensor could accurately detect glucose at significantly lower concentrations than enzymatic sensors.

In addition, the material also has active sites that offer greater charge transfer efficiency to catalyse electrochemical reactions. An example is the Oxygen Evolution Reaction (OER) – the slowest step in generating oxygen through various chemical reactions like electrolysis of water and reduction of carbon dioxide. These reactions are significant for storing energy in fuel cells and metal-air batteries. The team found that the HENAs@NCNTs were able to catalyse OER in water electrolysis just as efficiently as an expensive, benchmark catalyst called RuO2.

Employing abundantly available metals like iron, cobalt, nickel in making non-enzymatic catalysts and reusing such catalysts can thus pave the way for developing affordable glucose sensors and sustainable energy solutions.

REFERENCE:

Raj G, Nandan R, Gakhad P, Kumar K, Singh AK, Nanda KK, A novel electrochemical high-performance non-enzymatic glucose sensing based on face-centred cubic FeCoNiMnCr high entropy nano alloys encapsulated in NCNTs, Chemical Engineering Journal (2025).

https://doi.org/10.1016/j.cej.2024.158041

LAB WEBSITES:
https://mrc.iisc.ac.in/karuna-kar-nanda/
https://mrc.iisc.ac.in/abhishek-singh/