TY - GEN A1 - Ivanov, Svetlozar D. A1 - Kurniawan, Fredy A1 - Tsakova, Vessela T. A1 - Mirsky, Vladimir M. T1 - Automated layer-by-layer deposition of polyelectrolytes in flow mode T2 - Macromolecular Materials and Engineering N2 - 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. Y1 - 2009 U6 - https://doi.org/10.1002/mame.200800376 SN - 1439-2054 VL - 294 IS - 6-7 SP - 441 EP - 444 ER - TY - GEN A1 - Hodzhaoglu, Feyzim A1 - Kurniawan, Fredy A1 - Mirsky, Vladimir M. A1 - Nanev, Christo T1 - Gold nanoparticles induce protein crystallization T2 - Crystal Research and Technology N2 - Nucleation of protein crystals by gold nanoparticles was observed. Lysozyme and ferritin were used as model proteins. The effect was established with uncoated gold nanoparticles and with gold nanoparticles coated by 16-mercaptodecanoic acid. KW - gold nanoparticles KW - protein crystallization KW - nucleants KW - lysozyme KW - ferritin Y1 - 2008 U6 - https://doi.org/10.1002/crat.200811125 SN - 1521-4079 VL - 43 IS - 6 SP - 588 EP - 593 ER - TY - GEN A1 - Kurniawan, Fredy A1 - Tsakova, Vessela T. A1 - Mirsky, Vladimir M. T1 - Analytical applications of electrodes modified by gold nanoparticles: dopamine detection T2 - Journal of Nanoscience and Nanotechnology N2 - 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. KW - ascorbic acid KW - dopamine KW - electrochemical detection KW - gold nanoparticles KW - surface plasmon resonance Y1 - 2009 U6 - https://doi.org/10.1166/jnn.2009.SE13 SN - 1533-4880 SN - 1533-4899 VL - 9 IS - 4 SP - 2407 EP - 2412 ER - TY - GEN A1 - Kurniawan, Fredy A1 - Tsakova, Vessela T. A1 - Mirsky, Vladimir M. T1 - Gold nanoparticles in non-enzymatic electrochemical detection of sugars T2 - Electroanalysis N2 - 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. KW - Gold nanoparticles KW - Electrochemical KW - Glucose detection Y1 - 2006 U6 - https://doi.org/10.1002/elan.200603607 SN - 1521-4109 VL - 18 IS - 19-20 SP - 1937 EP - 1942 ER -