Enzymatic biofuel cell based on anode and cathode powered by ethanol.

Enzymatic biofuel cell based on enzyme modified anode and cathode electrodes are both powered by ethanol and operate at ambient temperature is described. The anode of the presented biofuel cell was based on immobilized quino-hemoprotein-alcohol dehydrogenase (QH-ADH), while the cathode on co-immobilized alcohol oxidase (AOx) and microperoxidase (MP-8). Two enzymes AOx and MP-8 acted in the consecutive mode and were applied in the design of the biofuel cell cathode. The ability of QH-ADH to transfer electrons directly towards the carbon-based electrode and the ability of MP-8 to accept electrons directly from the same type of electrodes was exploited in this biofuel cell design. Direct electron transfer (DET) to/from enzymes was the basis for generating an electric potential between the anode and cathode. Application of immobilized enzymes and the harvesting of the same type of fuel at both electrodes (cathode and anode) avoided the compartmentization of enzymatic biofuel cell. The maximal open circuit potential of the biofuel cell was 240mV.

Self-encapsulation of oxidases as a basic approach to tune the upper detection limit of amperometric biosensors.

This study describes a new, basic procedure for the tuning of some analytical parameters of enzymatic biosensors that are based on hydrogen peroxide-producing oxido-reductases. An amperometric biosensor based on glucose oxidase (GOx) (EC 1.1.3.4) from Penicillum vitale, immobilized on a carbon rod electrode by cross-linking with glutaraldehyde, was exploited as a model system for demonstration of the approach described here. Such an important analytical parameter as the upper detection limit was dramatically changed by the formation of a polypyrrole conducting polymer layer by the GOx-induced polymerization of polypyrrole (Ppy). An increase in the upper detection limits for differently modified electrodes was estimated by calculation of the apparent Michaelis-Menten constant [K(M(app))]. A significant increase in the long-term stability of the GOx-based electrode modified by Ppy (GOx/Ppy) was detected compared with that of an unmodified one. Further application of this approach, based on the self-encapsulation of glucose oxidase and other oxidases, is predicted for such biosensors where extension of the detection rate as well as K(M(app)) are required.

[Surface plasmon resonance and its application to biomedical research]. / Pavirsiaus plazmonu rezonansas ir jo pritaikymas biomedicininiams tyrinejimams.

In the recent years, surface plasmon resonance (SPR) has become one of the major methods for studying and determination of biologically active materials exhibiting affinity interactions. SRP biosensors are increasingly used in biochemistry and bioanalytical chemistry to determine antibody-antigen interactions, to investigate DNA hybridization, to diagnose bacteria- and virus-induced diseases, to identify hormones, steroids, and immunoglobulins, to investigate blood plasma coagulation. Using SPR biosensors, it is possible to analyze the mixtures of substances with a very similar chemical structure because SPR allows identifying only those analytes that specifically interact with biologically active substance immobilized on the surface of SPR biosensor. SPR biosensors are applied to monitor interactions between immobilized biologically active substance and analyte in real-time without labeling. On the other hand, it is possible to investigate not only association of analyte with immobilized material, but also the dissociation of a newly formed complex. SPR biosensors in many cases may be used to perform up to 50 measurements with the same SPR chip with an immobilized biological recognition element. Therefore, at present SPR is one of the most promising methods for determining the interactions between ligand and receptor, antigen and antibody, thus being increasingly used in diagnostics and biomedical research.

Biocompatibility of polypyrrole particles: an in-vivo study in mice.

The objectives of this study were the chemical synthesis of polypyrrole particles, the investigation and estimation of the impact of polypyrrole particle concentration, and the evaluation of the effect of duration of treatment on immune-related haematological parameters and peritoneum cells in mice. The results showed that chemically prepared polypyrrole particles did not have any detectable cytotoxic effect on mouse peritoneum cells. Polypyrrole particles did not induce any allergic response, nor did they affect spleen, kidney or liver indexes. Moreover, no effect of polypyrrole particles on immune-related haematological parameters was observed. No inflammation was detected in the peritoneum of mice after a 6-week period of treatment with polypyrrole particles. In conclusion, chemically synthesized polypyrrole particles showed good biocompatibility in mice and are attractive candidates for biomedical applications in-vivo.

Surface plasmon resonance label-free monitoring of antibody antigen interactions in real time.

Detection of biologically active compounds is one of the most important topics in molecular biology and biochemistry. One of the most promising detection methods is based on the application of surface plasmon resonance for label-free detection of biologically active compounds. This method allows one to monitor binding events in real time without labeling. The system can therefore be used to determine both affinity and rate constants for interactions between various types of molecules. Here, we describe the application of a surface plasmon resonance biosensor for label-free investigation of the interaction between an immobilized antigen bovine serum albumin (BSA) and antibody rabbit anti-cow albumin IgG1 (anti-BSA). The formation of a self-assembled monolayer (SAM) over a gold surface is introduced into this laboratory training protocol as an effective immobilization method, which is very promising in biosensing systems based on detection of affinity interactions. In the next step, covalent attachment via artificially formed amide bonds is applied for the immobilization of proteins on the formed SAM surface. These experiments provide suitable experience for postgraduate students to help them understand immobilization of biologically active materials via SAMs, fundamentals of surface plasmon resonance biosensor applications, and determination of non-covalent biomolecular interactions. The experiment is designed for master and/or Ph.D. students. In some particular cases, this protocol might be adoptable for bachelor students that already have completed an extended biochemistry program that included a background in immunology.

Biofuel cell based on direct bioelectrocatalysis.

A biofuel cell, consisting of two 3mm diameter carbon rod electrodes and operating at ambient temperature in aqueous solution, pH 6, is described. Biofuel cell based on enzymes able to exchange directly electrons with carbon electrodes was constructed and characterized. Anode of the biofuel cell was based on immobilized Quino-hemoprotein alcohol dehydrogenase from Gluconobacter sp. 33 (QH-ADH), cathode on co-immobilized glucose oxidase from Aspergilus niger (GO(x)) and microperoxidase 8 from the horse heart (MP-8) acting in the consecutive mode. Two enzymes GO(x) and MP-8 applied in the design of biofuel cell cathode were acting in consecutive mode and by hydrogen peroxide oxidized MP-8 was directly accepting electrons from carbon rod electrode. If ethanol was applied as an energy source the maximal open circuit potential of the biofuel cell was -125 mV. If glucose was applied as energy source the open circuit potential of the cell was +145 mV. The maximal open circuit potential (270 mV) was achieved in the presence of extent concentration (over 2 mM) of both substrates (ethanol and glucose). Operational half-life period (tau(1/2)) of the biofuel cell was found to be 2.5 days.