Kalanchoe sect. Bryophyllum leaf extract assisted sustainable MnWO₄ nanoparticles to enhance colorimetric detection of glucose molecules

In this study, MnWO₄ nanoparticles shows boundless growth for the utilization of noble nanocatalyst as the oxidase-mimicking material to achieve a sustainable and environment friendly procedure. MnWO₄ nanocatalyst were synthesized via hydrothermal approach using Bryophyllum leaves (Kalanchoe sect. Bryophyllum) green extract as a co-reducer for the colorimetric sensing of H₂O₂ and monosaccharide glucose. X-ray diffractogram (XRD) showed monoclinic crystallinity for the sample. Microstructural investigations depicted the presence of nanorod like structures of the material, using FESEM and HRTEM images. Through HRTEM images, the average particle size was calculated to be 53.4 nm, with the particle distribution curve showing the z-average size to be 80 nm. FTIR spectra validated the phase pure synthesis and formation of MnWO₄ nanoparticles as bend at 517 cm⁻¹ and 705 cm⁻¹ attributed to the Mn–o–Mn and W–O vibrations respectively. The nanocatalyst was employed for the colorimetric assessment of H₂O₂ and monosaccharide glucose, where the nanocatalyst oxidised 3,3′,5,5′‐tetramethylbenzidine (TMB), a colourless substrate to a bluish coloured product (oxTMB) with an absorbance shift at 652 nm. The nanoparticles have shown lower values of Michaelis and Menten constant represented as ‘k_m’ which show high affinity towards TMB. Herein, we have also demonstrated that our catalyst detects the H₂O₂ and glucose precisely. The detection limit of monosaccharide glucose was 2.08 µM with a linearity range of 20–100 µM. High catalytic activity, chemical stability and affordability provide the MnWO₄ nanoparticles with a significant potential as a commercial glucose sensor.