Electrochemical Biosensor Based on Gherkin (<i>Cucumis anguria</i>) Peroxidase Immobilized on Chitosan‐Coated Iron Oxide Nanoparticles for Phenolic Compounds Detection

This work presents the development of a sustainable and biocompatible electrochemical biosensor for the detection of phenolic compounds, leveraging peroxidase from Cucumis anguria (gherkin) homogenate and chitosan‐coated iron oxide nanoparticles ( γ ‐Fe 2 O 3 @CTS). A simple and cost‐effective method was used to prepare the enzymatic extract, with peroxidase activity confirmed spectrometrically. The γ ‐Fe 2 O 3 @CTS were synthesized with hydrodynamic radius of 146.8 ± 8.4 nm. Square wave voltammetry was employed to optimize experimental parameters for phenolic detection. Analytical curves were constructed for quercetin, morin, ferulic acid, and 2,5‐dihydroxybenzoic acid (2,5‐DHBA), showing excellent linearity and low detection limits of 0.0556, 24.2, 0.0102 and 1.72 μmol L −1 , respectively. These results highlight the potential of this biosensor for future applications in phenolic compound detection for environmental monitoring, food safety, and pharmaceutical industries, where phenolic compounds are significant markers. The biosensor's cost‐effectiveness, simplicity, and biocompatibility make it an attractive tool for on‐site and real‐time analysis of phenolic pollutants, improving sustainability in detection technologies.