Hierarchical microcrystalline cellulose/SeO₂-MnO₂/MWCNTs nanocomposite-based non-enzymatic electrochemical sensor for...

Reliable determination of hydrogen peroxide (H₂O₂) in food matrices requires sensitive and robust non-enzymatic electrochemical sensing strategies. Herein, we developed a hierarchical MCC/MnO₂-SeO₂@MWCNTs nanocomposite as a nanostructured-based non-enzymatic electrochemical interface for H₂O₂ determination. The proposed architecture integrates microcrystalline cellulose (MCC) with electroactive MnO₂-SeO₂ and a conductive multi-walled carbon nanotubes (MWCNTs) network to construct an electrochemically accessible sensing interface. The electrochemically active surface area increased from 0.253 cm² for the bare electrode to 0.412 cm² for the modified electrode, corresponding to a 63% increase. The nanocomposite and its individual components were characterized by Fourier-transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and chronoamperometry (CA) to define the physical and electrochemcial characteristics. Under optimized conditions, the modified carbon paste electrode exhibited a linear amperometric response to the H₂O₂ over 10-1200 µM, with a detection limit of 1.0 µM. The sensor exhibited good selectivity, repeatability, reproducibility, and storage stability. Accordingly, its applicability was tested across yellow cheese, salami, beef, milk, and burger samples, providing recoveries of 95.3-104.61% with low standard deviations (n = 5). Therefore, the integration of a MCC matrix with MnO₂-SeO₂ and MWCNTs, together with the experimentally demonstrated increase in electrochemically active surface area, provides a practical hierarchical interface for non-enzymatic H₂O₂ sensing in diverse food matrices.