Enzymatic electrochemical biosensor for glucose detection based on biomass-derived Fe₃O₄/C and PEDOT:PSS modification

Enzyme-based electrochemical biosensors allow sensitive and selective detection of blood glucose levels and enable diabetes patients personalize their treatment plans. Biocompatible, low-toxic, abundant and electroactive iron oxide (Fe₃O₄) nanoparticles are widely used as biosensor electrode materials. Herein, Fe₃O₄/Carbon (Fe₃O₄/C) nanocomposite was obtained through hydrothermal carbonization and successive calcination of heteroatom-rich spirulina (Arthrospira platensis, SP) biomass on Fe₃O₄ nanoparticles. Functionality and electrical conductivity of the Fe₃O₄/C nanocomposite was further enriched by a conductive poly(3,4-ethylenedioxythiophene) polystyrenesulfonate coating (Fe₃O₄/C/PEDOT:PSS). Glucose oxidase (GOx) was physically immobilized on the electrodes and glucose was detected by means of electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) methods. The glucose detection limits for the Fe₃O₄/C/GOx electrode were calculated as 0.73 mM (CV) and 1.04 mM (EIS) in the linear concentration range of 5–15 mM. The glucose detection limits for the Fe₃O₄/C/PEDOT:PSS/GOx electrode were calculated as 0.03 mM (CV) and 0.13 mM (EIS) in the linear concentration range of 0.5–1.5 mM. The selectivity of the biosensor was tested in the presence of ascorbic acid. Sensitive, selective, low-cost, and biocompatible electrodes provide a valuable tool in the management of diabetes.