@misc{LyutovIvanovMirskyetal., author = {Lyutov, Vladimir V. and Ivanov, Svetlozar D. and Mirsky, Vladimir M. and Tsakova, Vessela T.}, title = {Polyaniline doped with poly(acrylamidomethylpropanesulphonic acid): electrochemical behaviour and conductive properties in neutral solutions}, series = {Chemical Papers}, volume = {67}, journal = {Chemical Papers}, number = {8}, issn = {1336-9075}, doi = {10.2478/s11696-013-0341-9}, pages = {1002 -- 1011}, abstract = {Poly(2-acrylamido-2-methyl-1-propanesulphonic acid) (PAMPSA)-doped polyaniline (PANI) layers are synthesised in the presence of sulphuric and perchloric acids. The effects of the inorganic acid as well as of the electrochemical synthetic procedure (potentiostatic and potentiodynamic deposition) and thickness of the polymer layers are studied. The focus is directed towards the pH dependence of the electrochemical redox activity and conductivity of the PAMPSA-doped PANI layers obtained under different conditions. Ascorbic acid oxidation is used as a test reaction to study the electrocatalytic behaviour of various PAMPSA-doped PANI layers in neutral solution. It is found that the type of inorganic component present in the polymerisation solution has a marked effect on the extent of doping in acidic solutions as well as on the redox electroactivity in neutral solutions. A comparison between potentiostatically and potentiodynamically synthesised layers at pH 7 shows a markedly lower conductance and lower extent of redox charge preservation in the case of potentiodynamic synthesis. The PANI electrocatalytic activity for ascorbic acid oxidation is also dependent on the polymer electrodeposition procedure, with potentiostatically synthesised layers exhibiting better electrocatalytic performance.}, language = {en} } @misc{IvanovKurniawanTsakovaetal., author = {Ivanov, Svetlozar D. and Kurniawan, Fredy and Tsakova, Vessela T. and Mirsky, Vladimir M.}, title = {Automated layer-by-layer deposition of polyelectrolytes in flow mode}, series = {Macromolecular Materials and Engineering}, volume = {294}, journal = {Macromolecular Materials and Engineering}, number = {6-7}, issn = {1439-2054}, doi = {10.1002/mame.200800376}, pages = {441 -- 444}, abstract = {Multilayer structures of conducting polymers were fabricated by a simply automated approach in flow mode. Polyaniline and poly(styrene sulfonate) were used as a model system, allowing a fast electrochemical and spectroscopic determination of the amount of deposited material. The technology was applied for layer-by-layer deposition of up to 100 bilayers. The results demonstrate a well reproducible and almost constant amount of the adsorbed polymer at each deposition cycle. The method can be applied for deposition of other conducting or non-conducting polymers, biological macromolecules and composites of polyelectrolytes and nanoparticles.}, language = {en} } @misc{TsakovaIvanovLangeetal., author = {Tsakova, Vessela T. and Ivanov, Svetlozar D. and Lange, Ulrich and Stoyanova, Aneliya and Lyutov, Vladimir V. and Mirsky, Vladimir M.}, title = {Electroanalytical applications of nanocomposites from conducting polymers and metallic nanoparticles prepared by layer-by-layer deposition}, series = {Pure and Applied Chemistry}, volume = {83}, journal = {Pure and Applied Chemistry}, number = {2}, issn = {1365-3075}, doi = {10.1351/PAC-CON-10-08-01}, pages = {345 -- 358}, abstract = {Layer-by-layer (LbL) deposition is a convenient technique for the formation of ultra-thin nanocomposite layers containing metallic nanoparticles (NPs) and conducting polymers (CPs). The advantages of this approach for producing composite layers suitable for electroanalytical applications are discussed. Examples of electroanalytical applications of LbL-deposited composites are presented. Composite layers consisting of polyaniline (PANI) and Pd NPs are used for hydrazine oxidation. The PANI-Au NPs system is applied for dopamine (DA) and uric acid (UA) oxidation.}, language = {en} } @misc{IvanovLangeTsakovaetal., author = {Ivanov, Svetlozar D. and Lange, Ulrich and Tsakova, Vessela T. and Mirsky, Vladimir M.}, title = {Electrocatalytically active nanocomposite from palladium nanoparticles and polyaniline: Oxidation of hydrazine}, series = {Sensors and Actuators B: Chemical}, volume = {150}, journal = {Sensors and Actuators B: Chemical}, number = {1}, issn = {0925-4005}, doi = {10.1016/j.snb.2010.07.004}, pages = {271 -- 278}, abstract = {The layer by layer (LbL) adsorption technique was used to deposit a new electrocatalytic material consisting of palladium nanoparticles (Pd NPs) and polyaniline (PANI). As far as PANI adsorption did not affect the reactivity of the Pd NPs attached in the former adsorption step, the LbL technique offered the way of increasing the reactive Pd surface within a three-dimensional nanocomposite structure. In situ conductance measurements have shown that depending on the concentration of the PANI solution, used for the LbL adsorption, composites with either PANI-like (dependent on potential and pH) or metal-like (non-dependent on potential and pH) conductive behaviour can be obtained. Metal-like Pd NPs-PANI nanocomposites were studied as electrocatalytic materials for hydrazine oxidation. A linear concentration dependence of the voltammetric peak currents was observed in the 40-800 μM hydrazine concentration range, the sensitivity increasing with the amount of adsorbed Pd NPs. Amperometric measurements showed linear response in the 10-300 μM range with sensitivity 0.5 μA/μmol cm-2 and a theoretical detection limit estimated to be 0.06 μM.}, language = {en} } @misc{LangeIvanovLyutovetal., author = {Lange, Ulrich and Ivanov, Svetlozar D. and Lyutov, Vladimir V. and Tsakova, Vessela T. and Mirsky, Vladimir M.}, title = {Voltammetric and conductometric behaviour of self assembled multilayer nanocomposites of polyaniline and gold nanoparticles}, series = {Journal of Solid State Electrochemistry}, volume = {14}, journal = {Journal of Solid State Electrochemistry}, number = {7}, issn = {1432-8488}, doi = {10.1007/s10008-009-0922-2}, pages = {1261 -- 1268}, abstract = {Multilayer nanocomposites from polyaniline (PANI) and gold nanoparticles (AuNPs) were formed by layer-by-layer deposition. The formation of PANI-AuNPs multilayer structures was monitored by UV-vis absorption spectroscopy and cyclic voltammetry. Each deposited bilayer of PANI-AuNPs led to a monotonous and almost linear increase in both optical absorbance and the first current peak of PANI oxidation. The prepared multilayer nanocomposites were characterized by in situ conductivity measurements at different pH and potential and by transmission electron microscopy. Finally, chemosensitive properties of the new material based on the intrinsic affinity of gold nanoparticles were studied. Changes in the film resistance on exposure to vapors of mercury and sulfur-containing compounds were observed.}, language = {en} } @misc{KurniawanTsakovaMirsky, author = {Kurniawan, Fredy and Tsakova, Vessela T. and Mirsky, Vladimir M.}, title = {Analytical applications of electrodes modified by gold nanoparticles: dopamine detection}, series = {Journal of Nanoscience and Nanotechnology}, volume = {9}, journal = {Journal of Nanoscience and Nanotechnology}, number = {4}, issn = {1533-4880}, doi = {10.1166/jnn.2009.SE13}, pages = {2407 -- 2412}, abstract = {Dopamine oxidation was studied on modified gold (nano-Au) electrodes obtained by Layer-by-Layer deposition of gold nanoparticles and polyacrylic acid. A gradual loss of electrochemical activity for the dopamine oxidation reaction is observed at pH 7. Simultaneous SPR spectroscopy and cyclic voltammetry indicate the formation of an adsorbed layer on the electrode surface at this pH value. Investigations, performed through electrochemical and SPR measurements at pH 4, give evidence for a reversible process. At this pH value both dopamine oxidation and reduction current peaks show linear dependence on the dopamine concentration and may be used for analytical applications. The use of the nano-Au electrode allows resolving the peaks corresponding to ascorbic acid and to dopamine oxidation by 240 mV thus providing a high selectively for dopamine detection in the presence of ascorbic acid. The detection limit of this electrode for dopamine is below 4 microM in the presence of 1 mM ascorbic acid. The sensitivity normalized to the macroscopic electrode surface is about 10 mA cm(-2) mM(-1) at sweep rate of 10 V/s.}, language = {en} } @misc{KurniawanTsakovaMirsky, author = {Kurniawan, Fredy and Tsakova, Vessela T. and Mirsky, Vladimir M.}, title = {Gold nanoparticles in non-enzymatic electrochemical detection of sugars}, series = {Electroanalysis}, volume = {18}, journal = {Electroanalysis}, number = {19-20}, issn = {1521-4109}, doi = {10.1002/elan.200603607}, pages = {1937 -- 1942}, abstract = {A nonenzymatic electrochemical sensor for detection of sugars was prepared by layer-by-layer deposition of gold nanoparticles on thin gold electrodes. The deposition was optimized by using of surface plasmon resonance. Voltammetric investigation and impedance spectroscopy of the sensor was performed. Electrical currents caused by glucose on bare gold electrodes and on gold electrodes coated by immobilized gold nanoparticles were compared. The electrodes with nanoparticles display much higher current of glucose oxidation. The oxidation becomes blocked when the swept electrode potential exceeded +0.25 V, during the back scan an oxidation peak is observed again but at less positive potential. The magnitudes of these current peaks are linearly dependent on the glucose concentration; this dependence can be used as calibration for analytical applications. The limit of detection for glucose is below 0.5 mM, the sensitivity (normalized to the macroscopic electrode surface) is about 160 μA cm-2 mM-1. The sensor response is linear till at least 8 mM of glucose concentration.}, language = {en} } @misc{IvanovTsakovaMirsky, author = {Ivanov, Svetlozar D. and Tsakova, Vessela T. and Mirsky, Vladimir M.}, title = {Conductometric transducing in electrocatalytical sensors: Detection of ascorbic acid}, series = {Electrochemistry Communications}, volume = {8}, journal = {Electrochemistry Communications}, number = {4}, issn = {1388-2481}, doi = {10.1016/j.elecom.2006.02.006}, pages = {643 -- 646}, abstract = {Conductometric transducing is suggested for electrocatalytic chemical sensors based on conductive polymers. Lateral conductivity of the polymer layers was measured by two- and four-point techniques. The approach was applied for electroanalytical detection of ascorbic acid on the electrocatalytically active polyaniline and poly-ortho-methoxyaniline electrodes. Both polymers displayed a monotonous concentration dependence of their conductance in the analytically important sub-millimolar concentration range of ascorbic acid. The approach was tested in model solutions of ascorbic acid in buffer and applied for detection of ascorbic acid in orange juice.}, language = {en} }