Electroanalysis of an Iron@Graphene‐Carbon Nanotube Hybrid Material

Abstract

Hybrid nanomaterials have outstanding properties that are superior to the corresponding constituents working alone. This work reports on the electroanalysis of a hybrid material‐decorated screen‐printed carbon electrode (SPCE) that consists of iron nanoparticles supported at multi‐wall carbon nanotubes (MWCNT), coated with graphene layers, named Fe@G‐MWCNT. Electrochemical and morphological characterizations were carried out by cyclic voltammetry, electrochemical impedance spectroscopy and high‐resolution transmission electron microscopy, respectively. After optimizing the amount of hybrid material to be drop casted at the SPCE, its electrochemical activation in sulphuric acid produced an enhanced response. The resultant electrochemically reduced Fe@G‐MWCNT‐e‐modified electrode exhibited a diffusion‐controlled redox process with an enhanced heterogeneous electron‐transfer rate constant of 3.21×10−2 cm⋅s−1, which was superior to that from the MWCNT counterpart. However, it was slightly lower than that from a Fe‐MWCNT‐decorated electrode. The graphene coating limited slightly the electron‐transfer process, but works as a protective layer that prevent the loss of Fe catalytic activity. The electrochemical response of the hybrid with graphene coated Fe decreased only a 24.3 % after one week, respect to 51.9 % of the uncoated one. In addition, the hybrid material‐modified electrode exhibited electrocatalytic activity towards the reduction of H2O2 in a linear range of 0.5 mM to 9.8 mM, with sensitivity of 7.97 μA⋅mM−1 and LOD of 0.65 mM, thereby opening an avenue for the development of more specific and highly sensitive Fe@G‐MWCNT hybrid‐based (bio) sensors.

Peptide-based simple detection of SARS-CoV-2 with electrochemical readout

“…Fitting electrochemical parameters from EIS by a Randles equivalent circuit (Inset Fig. 1 B) was used to estimate the charge-transfer resistance (R ct ), the electrolyte resistance (R s ), the constant phase element (CPE), which depends on a pre-exponential factor (P) and an exponent (n) [ [55] , [56] , [57] , [58] ], as summarized in Table 1 .

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Hybrid Nanobioengineered Nanomaterial-Based Electrochemical Biosensors

“…Carbon-based nanomaterials have attracted increasing attention in electrochemical nano(bio)sensor development owing to their unique properties [68]. Among the carbonaceous nanomaterials, graphene and carbon nanotubes (CNT) have received considerable interest because they can be used simultaneously as transducer platforms, as matrixes to immobilize bioreceptors, and as signal amplification systems [46,69].…”

“…Graphene mainly has four forms, i.e., graphene itself; the oxidized form of chemically modified graphene (GO); the reduced form of graphene oxide (rGO); and graphene quantum dots (GQD), which have a size less than 10 nm [68,[74][75][76]. There are several reports about the synthesis of graphene, including chemical vapor deposition (CVD) [77], plasma-enhanced chemical vapor deposition (PE-CVD), cleavage of natural graphite, arc discharge, epitaxial growth of electrically insulating materials, solution-processable methods, and the microwave-assisted synthesis method [47].…”

“…Although acid treatments typically remove impurities, these treatments, in turn, can introduce other types of impurities, which may affect the physicochemical properties of nanotubes [90,91]. CNTs have been widely used in the development of electroactive platforms due to their unique properties such as electrical conductivity; relative biocompatibility; surface functionality; high surface area; high adsorption capacity; wide potential window; high mechanical, thermal, and chemical stability; and low background current [68,92]. In addition, CNT-based platforms have demonstrated higher sensitivity and better performance due to their 1D π-electron conjugation through hollow cylinders, which is responsible for the efficient capture and promotion of electron transfer from analytes and makes them very attractive in many applications.…”

Electrochemical Biosensors for Determination of Colorectal Tumor Biomarkers

“…With the progress in the fields of nanoscience and nanotechnology, a wide range of nanomaterials with excellent chemical, physical, and mechanical properties have been developed and adapted in biosensing platforms. They include several types of nanomaterials such as noble metals [75], metal oxides [76], metal chalcogenides [77], magnetic nanoparticles (NPs) [78], carbon-based nanomaterials [79], conductive polymers [80], etc. Among them, metal nanostructures have been attractive in the design of highly sensitive electrochemical biosensors.…”