Nanosized fibers containing carbon nanotube (CNT) were produced by electrospinning from a DMF solution containing CNT and polyacrilonitrile (PAN). The resulting fibers form a felt like fiber tissue that was used as an electrode. The nitrile groups of these fibers were chemically reduced to amines groups that were protonated at pH 5. The resulting positively charged nanofibers swell in aqueous solutions increasing the exposed surface of CNT and facilitating the diffusion of small molecules and ions to the conducting CNTs. The electrochemical behavior and the morphology of as prepared and reduced nanofibers were characterized by cyclic voltammetry and scanning electron microscopy (SEM) respectively. In addition, the influence of the reduction process determining the amount of amino groups, was investigated. The biofunctionalization of the nanofiber tissue electrodes was carried out by activation of the amino groups via incubation in glutaraldehyde vapor. Then, an enzyme model, polyphenol oxidase (PPO), was chemically grafted onto the nanofiber surface. The efficient covalent binding of PPO onto PAN–NH2–CNT electrodes (1 × 1 cm size), was exemplified through the electro-enzymatic detection of catechol. The resulting sensitivity and maximum current values at saturated catechol concentration are 118 mA mol−1 L and 10.66 μA respectively, with a detection limit of 0.9 μmol L−1.

Electrospun carbon nanofibres (CNFs) containing CNTs were produced by electrospinning and subsequent thermal treatment. This material was evaluated as a bioelectrode for biofuel cell applications after covalent grafting of laccase. Bis-pyrene-modified ABTS was used as a plug to wire laccase to the nanofibres leading to a maximum current density of 100 μA cm(-2).

Horseradish peroxidase and glucose oxidase were immobilized on redox buckypapers modified by poly(pyrrole-concanavalin) for the electroreduction of oxygen into water.

The design of redox buckypapersviacross-linking of carbon nanotubes with bis-pyrene modified ABTS.

The covalent grafting of carboxyphenyl functionalities to planar carbon substrates by reaction with 2-carboxybenezenediazonium salt has been studied in aqueous acid solution. The surface was characterized, before and after the functionnalization process, by cyclic voltammetry, electrochemical impedance spectroscopy and linear sweep voltammetry (LSV) in order to control and to prove the formation of a coating on the carbon surface. The results indicate the presence of substituted phenyl groups on the investigated surface. Electrochemical impedance measurements show that the slowing down of the electron transfer kinetics was more evident by increasing the number of cycles resulting to higher DEp and RCT parameters. Besides, the effect of the pH on the electron transfer processes of the Fe(CN)63-/4- at the modified electrode is studied. By changing the solution pH the terminal group’s charge state would vary, based on which the surface pKa value is estimated.

Electrochemical impedance spectroscopy was evaluated for the label free detection of MCF-7 cancer cell in which c-erbB-2 receptor is overexpressed on the cell surfaces. Anti-c-erbB-2, used as a specific antibody, was immobilized on electrogenerated polypyrrole-NHS on electrodes via covalent linking. The polymer formation, the grafting of the antibody, and the recognition event with the cancer cells using MCF-7 as a model cell line, were characterized by using cyclic voltammetry and fluorescence microscopy. The impedimetric sensor showed high sensitivity from 100 to 10 000 cell/mL without needing any labeling step and represents an efficient transduction method for cell selective detection.

An efficient way of immobilizing and wiring a large amount of laccase on non-covalently-functionalized multi-walled carbon nanotube (MWCNT) electrodes is reported. 1-(2-anthraquinonylaminomethyl)pyrene and 1-[bis(2-anthraquinonyl)aminomethyl]pyrene were synthesized and studied for their capability to non-covalently functionalize MWCNT electrodes and immobilize and orientate laccase on the nanostructured electrodes. This led to high-performance biocathodes for oxygen reduction by direct electron transfer with maximum current densities of (1±0.2) mA cm(-2). The performance of the resulting bioelectrodes could be doubled simply by using the bis-anthraquinone compound. The bioelectrodes show excellent stability over weeks and can thus be envisioned in enzymatic biofuel cells.