“Crude” extracts obtained by ultrasonic disintegration of microorganisms are promising bioelectrocatalysts. Extracts from Saccharomyces cerevisiae are of particular interest because they may contain a significant number of enzyme systems that oxidize simple carbohydrates such as glucose. A technology for producing “crude” protein extracts of Saccharomyces cerevisiae has been developed. The percentage of glucose added to the nu-trient medium, as well as the composition of the buffer solution at the resuspending stage, the power and time of ultrasonic disintegration of biomass, the rate and time of centrifugation during separation of the sediment of destroyed cells from the filler fluid have a significant effect on the enzymatic activity of the resulting “crude” extract.

“Crude” extracts are a new perspective type of bioelectrocatalysts for biofuel cells. The method of obtaining a “crude” extract by disintegrating bacterial cell membranes (for example, by ultrasound) is simpler and more economical in comparison with pure enzymes. From a scientific point of view, the study of the biocatalytic properties of “crude” extracts is very interesting, since the disintegrated biomass contains a cascade of enzymes involved in the metabolism of microorganisms and coenzymes necessary for oxidative/reductive transformation. This set of bioactive substances makes it possible to simulate the processes occurring during the operation of a “natural” fuel cell in an artificial environment. The effect of the pH and composition of the LB nutrient medium used in the cultivation of E.coli on the dehydrogenase activity of protein extracts obtained from this culture was studied. It is shown that by selecting the pH and modifying the composition of the LB nutrient medium, it is possible to increase the value of the specific dehydrogenase activity of extracts by almost 9 times (from 0.25 to 2.2 mg/mg).

The performance of a bioanode based on living cells Escherichia coli in the electrochemical oxidation of glucose is studied. It is shown that potassium ferricyanide can serve as the mediator in this bioelectrocatalytic system. The efficiency of this bioelectrocatalytic reaction with living cells depends on the mediator concentration. It is shown that the nature of buffer can affect the electrochemical responses of this system.

The kinetics of bioelectrocatalytic oxidation of glucose by protein extracts—supersonic-destruction products of Escherichia coli BB cells—is studied in the presence of [Fe(CN)6]3– as the mediator system. The effect of the concentration of mediator, glucose, and protein extract is studied by electrochemical methods. The results are used in determination of effective parameters: the rate constant of glucose biooxidation, the constant of substrate-induced inhibition, and the activation energy. It is shown that the activation energy of this reaction falls into the interval of activation energies of dehydrogenase reactions. The voltammetric characteristics of a model asymmetrical biofuel cell which employs the protein extract as the anodic catalyst are determined. The maximum specific power of such model biofuel cell is found to be 400 µW/cm2 (4 W/m2).

«Crude» extracts obtained via simple ultrasonic disintegration of microbial cell membrane are perspective bioelectrocatalysts. This extract contains all the necessary enzymes and cofactors required for oxidative or reductive conversion. The technology of synthesis of «crude extract» is simpler and less costly in comparison with technology of obtaining pure enzymes. Dialysis of the obtained extracts was performed with different molecular weight cut-off (3.5 kDa, 12-14 kDa, 25 kDa, 50 kDa). The obtained data show that after dialysis extracts lose their dehydrogenase and bioelectrocatalytic activity due to the loss of cofactors. However, the addition of NAD and NADP cofactors leads to a recovery of activity. The obtained data demonstrate that the concentration of the cofactor directly affects the rate of the bioelectrocatalytic reaction. Also, the obtained data indicate that the composition of the enzyme systems of the extract includes succinate dehydrogenase. Analyzing this data set can provide insight on increase of the electrocatalytic activity of a new type of bioelectrocatalyst.

A protein extract of microbe cells is studied as a bioelectrocatalyst for glucose oxidation. The microbial protein extract prepared from Escherichia coli BB, which comprises all enzymes of the life cycle of these bacteria, is considered here as a model system. This system demonstrates the mediator mechanism of interaction with an inert glassy-carbon electrode in a buffer containing glucose as the substrate. The efficiency of the bioelectrocatalytic process was shown to depend on the type of mediator system and also on the nature of buffer, its temperature, pH, and ionic strength. The protein extract is shown to contain NAD-dependent Fe-glucosodehydrogenase and demonstrate the current densities in mediator-assisted glucose oxidation well comparable with the known data for pure dehydrogenase enzymes and E. coli microbial systems. The prospects for further studies and practical applications of this new bioelectrocatalyst type are outlined.

Palladium nanoparticles–polypyrrole composite (Pd/PPy) catalyzes the addition of perfluoroalkyl halides to olefins to produce a variety of products with good yields. An effective fluoroalkylation technique tested with various olefins, fluoroalkyl halides and Pd/PPy was developed. The reaction proceeds highly efficient under mild phosphine-free reaction conditions with different substrates, easy catalyst recycling and provides a general and straightforward access to fluoroalkylated products. Furthermore, we were able to control whether the addition of perfluoroalkyl occurs with various monomer (fluoroalkylated alkene or alkane with RF and OH moieties) or dimer formation (under electrochemical conditions).

The dehydrogenase activity of Escherichia coli BB cell extracts was studied at different growth stages in the presence of different substrates and triphenyl tetrazolium chloride as an electron acceptor. It was shown that the highest degree of reduction of triphenyl tetrazolium chloride was observed during exponential growth of the bacteria when potassium isocitrate was used as a substrate. It was found that extracts of the bacteria during the exponential phase of growth on an inert glassy carbon electrode in a three-electrode liquid electrochemical cell manifested electrochemical activity in the presence of potassium citrate and methylene blue or potassium hexacyanoferrate(III) as redox mediators.