Nanobioengineered\nAl<sub>2</sub>O<sub>3</sub> Core–Shell\nNanoparticle Preparation Using Bauhinia Variegate Plant Extract for Efficient Photocatalysis and Electrochemical Sensing

Core–shell-based\nnanomaterials have garnered considerable\nattention in the recent past not only in catalytic applications but\nalso in their potentiality in selective and efficient sensing. Present\nresearch reports the first and successful biosynthesis of the core\n(c-Al<sub>2</sub>O<sub>3</sub>)–shell nanoparticles (NPs) using Bauhinia variegate blossom extract as reducing and\ncapping agents. The synthesized c-Al<sub>2</sub>O<sub>3</sub> NPs\nwere characterized and utilized to fabricate nanobioengineered electrodes\non indium tin oxide (ITO) substrates via electrophoretic deposition.\nElectrochemical analysis, including cyclic voltammetry and differential\npulse voltammetry, revealed quasi-reversible processes with high electron-transfer\nrates (<i>K</i><sub>s</sub> = 0.66 s<sup>–1</sup>) and a diffusion coefficient (<i>D</i> = 5.84 × 10<sup>–2</sup> cm<sup>2</sup> s<sup>–1</sup>). The electrode\nexhibited a very high sensitivity (23.44 μA μM<sup>–1</sup> cm<sup>–2</sup>) and a low detection limit (0.463 μM)\nfor sodium azide (NaN<sub>3</sub>) over two linear ranges of 1–6\nand 8–20 μM. Additionally, c-Al<sub>2</sub>O<sub>3</sub> NPs demonstrated the effective photocatalytic degradation of crystal\nviolet dye under visible light, following pseudo-first-order kinetics.\nThe fabricated electrode showed excellent selectivity, stability,\nand reproducibility, highlighting its potential for environmental\nmonitoring and clinical diagnostics.