A Highly Efficient Electrochemical Biosensing Platform by Employing Conductive Nanocomposite Entrapping Magnetic Nanoparticles and Oxidase in Mesoporous Carbon Foam

Abstract

A conductive multi‐catalyst system consisting of Fe3O4 magnetic nanoparticles (MNPs) and oxidative enzymes co‐entrapped in the pores of mesoporous carbon is developed as an efficient and robust electrochemical biosensing platform. The construction of the nanocomposite begins with the incorporation of MNPs by impregnating Fe(NO3)3 on a wall of mesoporous carbon followed by heat treatment under an Ar/H2 atmosphere, which results in the formation of magnetic mesoporous carbon (MMC). Glucose oxidase (GOx) is subsequently immobilized in the remaining pore spaces of the MMC by using glutaraldehyde crosslinking to prevent enzyme leaching from the matrix. H2O2 generated by the catalytic action of GOx in proportion to the amount of target glucose is subsequently reduced into H2O by the peroxidase mimetic activity of MNPs generating cathodic current, which can be detected through the conductive carbon matrix. To develop a robust and easy‐to‐use electrocatalytic biosensing platform, a carbon paste electrode is prepared by mechanically mixing the nanocomposite or MMCs and mineral oil. Using this strategy, H2O2 and several phenolic compounds are amperometrically determined employing MMCs as peroxidase mimetics, and target glucose was successfully detected over a wide range of 0.5 × 10−3 to 10 × 10−3 M, which covers the actual range of glucose concentration in human blood, with excellent storage stability of over two months at room temperature. Sensitivities of the biosensor (19 to 36 nA mM−1) are about 7–14 times higher than that of the biosensor using immobilized GOx in mesoporous carbon without MNPs under optimized condition. The biosensor is of considerable interest because of its potential for expansion to any oxidases, which will be beneficial for use in practical applications by replacing unstable organic peroxidase with immobilized MNPs in a conductive carbon matrix.

Recent Advances in Nanozyme Research

“…Among them nanoparticle (NP) based catalysts have attracted increasing interest. Up to now, various NPs made of metals, metal oxides, and carbons have been reported to resemble the functions of various enzymes‐like oxidase, peroxidase, catalase, and superoxide dismutase . Recent studies revealed that activities of NPs are greatly dependent on the particle size, shape, and surface facets, which could be affected by charges, coatings, dopings, loadings, and external fields.…”

Ferromagnetic nanoparticles with peroxidase-like activity enhance the cleavage of biological macromolecules for biofilm elimination

“…10, 15 MNP are promising nanocatalysts because of their magnetic properties, high catalytic activity, and adjustability through nanoscale modifications 10, 16–19 , suggesting possible uses in immunoassays 10, 13, 20, 21 , organic pollutant degradation 12, 22–26 , glucose detection 17, 18, 27–31 and cancer diagnostics. 14 Although it has been reported that MNP alone or combined with H 2 O 2 can prevent biofilm formation by inhibiting bacterial growth, 32, 33 there are no reports regarding the efficacy of an MNP-H 2 O 2 system on biofilm destruction and killing of bacteria resident within biofilms—a much more difficult medical challenge.…”

Recent Research Trends and Future Prospects in Nanozymes

“…There have been several reports of an electrochemical biosensing platform using GOx-coupled nanozymes. A highly efficient and robust electrochemical biosensing strategy employing a nanocomposite harboring GOx-coupled nanozymes was developed by our group [49]. In this report, MNPs and GOx were entrapped in the pores of mesoporous carbon, in which GOx immobilized in the nanocomposite generates H 2 O 2 which then is directly reduced to H 2 O, with the electrocatalytic reduction mediated by MNPs.…”