Direct electrochemistry and electrocatalysis of horseradish peroxidase immobilized in graphene oxide–Nafion nanocomposite film

An enhanced electrochemical performance of in milk, pigeon meat and eggs samples using se nanorods capped with Co3O4 nanoflowers decorated on graphene oxide

In this work, we report a novel preparation of selenium nanorods (Se) doped cobalt oxide (Co₃O₄) nanoflowers encapsulated with graphene oxide (GO) nanocomposite (NC). Se nanorods were successfully decorated on Co₃O₄ nanoflowers and an increase in electrical conductivity was observed in Se-Co₃O₄@GO-NC. The as-prepared Se-Co₃O₄@GO-NC was utilized as an effective nanocomposite for the electrochemical detection of dimetridazole (DMZ) for the first time in the field of electrochemical sensors. Se-Co₃O₄@GO-NC modified glassy carbon electrode (GCE) which showed an excellent cathodic current response (17.6 μA) at the lower potential at -0.7314 V upon DMZ sensing. With the various optimized conditions, Se-Co₃O₄@GO-NC based electrochemical sensor displayed a lengthy linear range of 0.02-83.72 μM, limit of detection 3.4 nM and sensitivity of 1.898 μA.μM^-1. cm^-2 for DMZ detection. In addition, Se-Co₃O₄@GO-NC revealed fabulous catalytic reduction activity for DMZ, when compared to GO and Se-Co₃O₄ modified GCE. Additionally, Se-Co₃O₄@GO-NC is applied in real sample analysis of pigeon egg, milk and pigeon meat. The results illustrated that Se-Co₃O₄@GO-NC can be a promising nanocomposite for the electrocatalytic reduction of DMZ in clinical samples in biomedical field.

3D-printed graphene direct electron transfer enzyme biosensors

Three-dimensional (3D) printing technology offers attractive possibilities for many fields. In electrochemistry, 3D printing technology has been used to fabricate customized 3D-printed electrodes as a platform to develop bio/sensing, energy generation and storage devices. Here, we use a 3D-printed graphene/polylactic (PLA) electrode made by additive manufacturing technology and immobilize horseradish peroxidase (HRP) to create a direct electron transfer enzyme-based biosensors for hydrogen peroxide detection. Gold nanoparticles are included in the system to confirm and facilitate heterogeneous electron transfer. This work opens a new direction for the fabrication of third-generation electrochemical biosensors using 3D printing technology, with implications for applications in the environmental and biomedical fields.

Molecular effects of encapsulation of glucose oxidase dimer by graphene

A box-like shape of graphene leads to different types of “sandwich” or “burrito” encapsulation of the enzyme. To preserve the critical interactions in the enzyme active site a proper balance of forces between protein and graphene is required.

Graphene-based electrochemical sensors

Graphene, one kind of emerging carbon nanomaterial, has attracted increasing attention recently. Due to its fascinating physical and electrochemical properties, graphene as a promising electrode material has been widely used in electrochemical sensing applications. In this review, different approaches for the fabrication of graphene and the preparation of graphene-modified electrodes for electrochemical sensors are introduced. Moreover, recent research results on different graphene-based materials as an electrochemical platform for the detection of various biomolecules and chemicals are reviewed and compared. More electrochemical studies on this novel material should show up in the near future.

Supramolecular assembly of enzyme on functionalized graphene for electrochemical biosensing

The self-assembly of cyclodextrin (CD) functionalized graphene (GR) and adamantane-modified horseradish peroxidase (HRP-ADA) by host-guest supramolecular interaction into novel nanostructures in aqueous solution is reported in the present study. Electrochemical impedance spectroscopy and cyclic voltammetry were applied to characterize the self-assembly process and study the electrochemical behaviors of the immobilized proteins. UV-vis spectra indicated that the native structure of HRP was maintained after the assembly, implying good biocompatibility of CD-functionalized GR (CD-GR). Furthermore, the HRP-ADA/CD-GR composites were utilized for the fabrication of enzyme electrodes (HRP-ADA/CD-GR electrodes). The proposed biosensor showed good reproducibility and high sensitivity to H2O2 with the detection limit of 0.1 μM. In the range of 0.7-35 μM, the catalytic reduction current of H2O2 was proportional to H2O2 concentration.