Wyniki wyszukiwania - BazTech

1

Oznaczanie tlenu : od metody Winklera do czujników enzymatycznych

Dramińska S., Biernat J. F., Bilewicz R.

Wiadomości Chemiczne

|

2015

|

[Z] 69, 9-10

751--766

EN

Monitoring of dioxygen levels is of utmost importance from the view-point of life processes, medical diagnostics, nutrition and chemical industries. In all these measurements both low and high levels of this element are important. The common methods for the determination of dioxygen are the Winkler method, Clark electrode and pulsoxymeters. A new, already strong field of research can be now recognized – the development of miniaturized biosensors of dioxygen, characterized by short response time, selectivity and utility in continuous monitoring of dioxygen. This trend can be seen in all fields where analytical methods are applied. The aim is to construct simple and, therefore, low cost devices and a good example of such device is the enzymatic biocathode sensitive towards dioxygen. The main issue in the construction of such electrodes is how to immobilize a redox enzyme on the conductive support in a way allowing to retain its full activity and to provide efficient transfer of charge between the electrode and the active centres of the enzymes. The difficulty in achieving suitable electrical contact can be solved by applying suitable carbon nanomaterials, increasing the working surface of the electrode and providing access to the active centres of the enzyme molecules.

2

Synthesis and modification of reduced graphene oxide aerogels for biofuel cell applications

Kondratowicz I., Żelechowska K., Majdecka D., Bilewicz R.

Materials Science Poland

|

2015

|

Vol. 33, No. 2

292--300

EN

We have carried out the preparation of reduced graphene oxide aerogels using eco-friendly method that is based on the Hummers method of graphite oxidation without the use of NaNO3 that produces toxic gases. To obtain a porous 3D structure of reduced graphene oxide, we performed the hydrothermal reduction at elevated temperature. We also prepared the rGO aerogel/CNT composite using multiwalled carbon nanotubes as linkers. The rGO aerogels are promising materials as they possess good electrical conductivity (up to 100 S/m) and high surface area and porous structure (similar to 500 m(2)/g). The main goal was to obtain the material for electrodes in enzymatic biofuel cells. Thus, the proper modification was performed using free radical functionalization. It was shown that in order to synthesize rGO aerogels modified with anthracene, the proper order of reactions needs to be provided. The morphology of anthracene modified electrodes was analyzed using scanning electron microscopy, which confirmed their porous structure with non-uniform pore size distribution that ranged between few nanometers to microns. Data obtained by Raman spectroscopy confirmed the successful oxidation and reduction of analyzed materials. UV-Vis spectra revealed the presence of anthracene moieties in examined materials. We also recorded preliminary cyclic voltammograms that confirm an electric conductivity of the obtained structures.

3

Aryl and N-arylamide carbon nanotubes for electrical coupling of laccase to electrodes in biofuel cells and biobatteries

Żelechowska K., Stolarczyk K., Łyp D., Rogalski J., Roberts K. P., Bilewicz R., Biernat J. F.

Biocybernetics and Biomedical Engineering

|

2013

|

Vol. 33, no. 4

235--245

EN

Single walled carbon nanotubes (SWCNTs) were equipped with aryl residues by chemical reactions. These insoluble materials were used to substitute classical soluble mediators, which help to transfer electrical charge between the conducting electrode and the redox active center of enzyme molecules. The effect of different aryl residues on the efficiency of the catalytic reduction of dioxygen in the presence of laccase was systematically studied using voltammetry and measuring the power output of a biofuel cell.

4

Carbon nanotubes chemically derivatized with redox systems as mediators for biofuel cell applications

Bilewicz R., Nazaruk E., Żelechowska K., Biernat J. F., Stolarczyk K., Roberts K. P., Ginalska G., Rogalski J.

Biocybernetics and Biomedical Engineering

|

2011

|

Vol. 31, no. 4

17-30

EN

The aim of this study was designing of nanostructured bioelectrodes and assembling them into a biofuel cell with no separating membrane. Carbon nanotubes (CNTs) chemically connected with residues of typical mediators, i.e. ferrocene (Fc) and 2,2'-azino-bis-(3-ethylbenzothiazoline)-6-sulfonic acid (ABTS) deposited on glassy carbon electrodes (GCE) were found useful as mediators for the enzyme catalyzed electrode processes. The electrodes were in turn covered with glucose oxidase from Aspergillus niger AM-11 and laccase from Cerrena unicolor C-139, respectively, incorporated in a liquid-crystalline matrix. The nanostructured electrode coating with the cubic phase film containing enzymes acted as the catalytic surface for the enzymatic reactions that is oxidation of glucose at anode and reduction of oxygen at cathode. For the system with mediators anchored to CNTs the catalysis was almost ten times more efficient than on bare GCE electrodes: catalytic current of glucose oxidation was 1 mAcm-2 and oxygen reduction current exceeded 0.6 mAcm-2. The open circuit voltage of the biofuel cell was 0.43 V. Application of the carbon nanotubes increased maximum power output of the constructed biofuel cell to 100 \miWcm-2 without stirring the solution. It is ca. 100 times more efficient than using the same bioelectrodes without nanotubes on the electrode surface.

5

Chemically Modified Carbon Nanotubes: Synthesis and Implementation

Sadowska K., Jabłonowska E., Stolarczyk K., Wiser R., Bilewicz R., Roberts K. P., Biernat J. F.

Polish Journal of Chemistry

|

2008

|

Vol. 82, nr 6

1309-1313

6

Catalytic Applications of Electrodes Modified with Thiolated Cyclodextrins

Wawrzyniak U. E., Chmurski K., Rogalski J., Bilewicz R.

Polish Journal of Chemistry

|

2008

|

Vol. 82, nr 6

1283-1287

7

Photoconducting Properties of Fullerene Derivatized with a Biphenyl Moiety

Trzcińska K., Bilkova P., Szydłowska J., Mieczkowski J., Bilewicz R., Pociecha D., Gorecka E.

Polish Journal of Chemistry

|

2006

|

Vol. 80, nr 11

1899-1907

EN

The properties of low molecular weight molecules, in which the electron-acceptor fullerene unit was linked by malonate group and flexible long alkyl chains to two biphenyl-phenyl units, were studied. Cyclic voltammetry measurements showed five consecutive one-electron, reversible electro-reductions for the fullerene unit and a single two-electron, reversible electro-oxidation for biphenyl moiety. The two electron process indicated that two biphenyl moieties interacted; presumably folded conformation was formed with two electron donating moieties at close proximity. Along-living charge-separated state induced upon light absorption was confirmed by the ESR spectroscopy studies. These properties were responsible for observed photoconductivity of the studied compound.

8

Design of Ferrocene Organothiol Monolayer as Intermediate Phase for Miniaturized Electrochemical sensors with Gold Contact

Sęk S., Bilewicz R., Grygołowicz-Pawlak E., Grudzień I., Brzózka Z., Malinowska E.

Polish Journal of Chemistry

|

2004

|

Vol. 78 / nr 9

1655-1665

EN

New design of back side contact (BSC) chips for miniaturized electrochemical sensors with Au contact modified by monolayers of purposely synthesized organothiol molecules is described. Voltammetric studies of the monolayers indicate reversible behavior of the compounds and efficient coverage of the gold electrode. Properties of 5 compounds are compared. The electroactive benzenethiol based self-assembled monolayer is selected as a convenient intermediate layer in solid contact potentiometric sensors since it forms a hydrophobic barrier between the electrode and the solution and at the same time provides efficient electronic wiring to the electrode. Stable electrode performance is obtained and the potentiometric response remains as fast as using bare gold contact which should be favorable for the application of the described intermediate layers in ion-selective electrodes.

9

ph Dependent Enantioselection of Amino Acids by Phosphorous-Containing Calix[4]resorcinarene in Langmuir Monolayers

Pietraszkiewicz M., Prus P., Bilewicz R.

Polish Journal of Chemistry

|

1999

|

Vol. 73, nr 12

2035-2042

EN

Lipophilic calix[4]resorcinarene with phosphorous acid amide groups linking oxygen atoms is a rigid system of the cavitand type, in which conformational flexibility is strongly limited. These chiral receptors form stable Langmuir monolayers on water surface with surface area per molecule in the compressed layer being almost ph-independent.

10

pH Dependent Enantiomeric Recognition of Amino Acids by Mannich-Type Calix[4]resorcinarenes in Langmuir Monolayers

Pietraszkiewicz M., Prus P., Bilewicz R.

Polish Journal of Chemistry

|

1999

|

Vol. 73, nr 11

1845-1853

EN

The surface potential of these compounds is distinctly higher in the presence of substituents and its further increase upon decreasing the pH of the subphase is observed only for the derivatized calixarenes. This means that protonation on the amine centers is the factor determining the properties of the monolayer.

11

Synthesis, spectral and electrochemical characterization of transition metal homodinuclear complex (Co(2+), Cu(2+), Ni(2+) with macrocyclic 34-membered hexaamine

Pietraszkiewicz M., Pietraszkiewicz O., Bujno K., Bilewicz R.

Polish Journal of Chemistry

|

1998

|

Vol. 72, nr 5

852-859

EN

34-membered macrocyclic hexaamine containing two independent N-3 donor sets forms homodinuclear transition metal complexes with cobalt(II), copper(II), and nickel(II). Titration experiments show that the homodinuclear complexes are formed exclusively without formation of mononuclear complexes. Displacements of anions within the copper(II) complexes occur easily upon addition of different anions to the CuCl2 complex. All new complexes are characterized by elemental analysis, IR and UV/VIS spectroscopy, and cyclic voltammetry. The dinuclear Cu(II) complex both in the solution and immobilized in Nafion layer on the electrode undergoes revesible l e reduction independently at each copper center and exhibits catalytic activity towards oxygen reduction.