Three dimensional film electrode prepared from oppositely charged carbon nanoparticles as efficient enzyme host

Chemical and Biochemical Approach to Make a Perfect Biocatalytic System on Carbonaceous Matrices

Enzymatic processes are widely used in food industry, pharmacy, cosmetic and household chemistry, and medicine. However, the common and efficient application of the biological catalysts is limited by a number of factors that influence enzymes activity. One of the most frequent methods to improve the biocatalysts' properties is immobilization. This chapter presents a recent overview of our attempts to obtain the perfect biocatalytic system. The experimental approach, proposed in this chapter, includes the critical points like: the choice of adequate immobilization method, most suitable carrier, determination of enzyme kinetic parameters, stability, and toxicity of obtained systems. As carbon materials including graphene-derived materials offer unique properties and a plenty of different modifications, these parameters seem to be of decisive importance to understand chemistry of complex systems. Consideration of all the mentioned requirements lead us to the conclusion that graphene oxide could be the best candidate for support in perfect biocatalytic systems.

Controlling enzymatic activity by immobilization on graphene oxide

In this study, graphene oxide (GO) has been applied as a matrix for enzyme immobilization. The protein adsorption capacity of GO is much higher than of other large surface area carbonaceous materials. Its structure and physicochemical properties are reported beneficial also for enzymatic activity modifications. The experimental proof was done here that GO-based biocatalytic systems with immobilized catalase are modifiable in terms of catalyzed reaction kinetic constants. It was found that activity and stability of catalase, considered here as model enzyme, closely depend on enzyme/GO ratio. The changes in kinetic parameters can be related to secondary structure alterations. The correlation between enzyme/GO ratio and kinetic and structure parameters is reported for the first time and enables the conscious control of biocatalytic processes and their extended applications. The biological activity of obtained biocatalytic systems was confirmed in vitro by the use of functional test. The addition of immobilized catalase improved the cells' viability after they were exposed to hydrogen peroxide and tert-butyl-hydroperoxide used as source of reactive oxygen species.

How the Intricate Interactions between Carbon Nanotubes and Two Bilirubin Oxidases Control Direct and Mediated O2 Reduction

Due to the lack of a valid approach in the design of electrochemical interfaces modified with enzymes for efficient catalysis, many oxidoreductases are still not addressed by electrochemistry. We report in this work an in-depth study of the interactions between two different bilirubin oxidases, (from the fungus Myrothecium verrucaria and from the bacterium Bacillus pumilus), catalysts of oxygen reduction, and carbon nanotubes bearing various surface charges (pristine, carboxylic-, and pyrene-methylamine-functionalized). The surface charges and dipole moment of the enzymes as well as the surface state of the nanomaterials are characterized as a function of pH. An original electrochemical approach allows determination of the best interface for direct or mediated electron transfer processes as a function of enzyme, nanomaterial type, and adsorption conditions. We correlate these experimental results to theoric voltammetric curves. Such an integrative study suggests strategies for designing efficient bioelectrochemical interfaces toward the elaboration of biodevices such as enzymatic fuel cells for sustainable electricity production.

Positively charged carbon nanoparticulate/sodium dodecyl sulphate bilayer electrode for extraction and voltammetric determination of ciprofloxacin in real samples

The modified electrode was prepared using a layer-by-layer method with functionalized CNPs and SDS. The ability of modified electrode to adsorb ciprofloxacin was investigated. Ciprofloxacin was analyzed in real samples.

Recent Developments of Nanostructured Electrodes for Bioelectrocatalysis of Dioxygen Reduction

The recent development of nanostructured electrodes for bioelectrocatalytic dioxygen reduction catalysed by two copper oxidoreductases, laccase and bilirubin oxidase, is reviewed. Carbon-based nanomaterials as carbon nanotubes or carbon nanoparticles are frequently used for electrode modification, whereas there are only few examples of biocathodes modified with metal or metal oxide nanoparticles. These nanomaterials are adsorbed on the electrode surface or embedded in multicomponent film. The nano-objects deposited act as electron shuttles between the enzyme and the electrode substrate providing favourable conditions for mediatorless bioelectrocatalysis.