Direct electrochemistry of adsorbed proteins and bioelectrocatalysis at film electrode prepared from oppositely charged carbon nanoparticles

Highlights: ► Entirely carbon nanoparticlulate film electrodes were prepared by layer-by-layer method. ► Their average thickness was determined by atomic force microscopy and can be controlled by the number of immersion and withdrawal steps. ► The material has a highly developed electroactive surface. ► Direct voltammetry of adsorbed myoglobin and glucose oxidase on carbon nanoparticlulate film electrodes was obtained. ► The electrodes were used as supports for enzymatic bioelectrocatalysis. -- Abstract: Carbon nanoparticulate film electrodes were prepared by alternative immersion of indium tin oxide plates into suspension of positively and negatively charged carbon nanoparticles. Their average thickness is in the range of 30–300 nm as determined by atomic force microscopy and depends on the number of immersion and withdrawal steps. After adsorption of myoglobin the voltammetric signal corresponding to redox reaction of heme prosthetic group is observed. This electrode exhibits bioelectrocatalytic hydrogen peroxide reduction with cathodic current linearly dependent on concentration in millimolar range. After adsorption of glucose oxidase the electrode exhibits well defined voltammetric signal attributed to the electrochemical reaction of redox cofactor FAD. In oxygenated solution the cathodic current decreases and is linearly dependent on glucose concentration in the millimolar range. In the presence of mediator – ferrocene carboxylate, bioelectrocatalytic oxidation of glucose is seen. The magnitude of the redox voltammetric signal of both enzymes is roughly proportional to the amount of nanoparticulate material