TY - THES A1 - Lysyakova, Liudmila T1 - Interaction of azobenzene containing surfactants with plasmonic nanoparticles T1 - Wechselwirkung zwischen Azobenzol-haltigen Tensiden und plasmonischen Nanoteilchen N2 - The goal of this thesis is related to the question how to introduce and combine simultaneously plasmonic and photoswitching properties to different nano-objects. In this thesis I investigate the complexes between noble metal nanoparticles and cationic surfactants containing azobenzene units in their hydrophobic tail, employing absorption spectroscopy, surface zeta-potential, and electron microscopy. In the first part of the thesis, the formation of complexes between negatively charged laser ablated spherical gold nanoparticles and cationic azobenzene surfactants in trans- conformation is explored. It is shown that the constitution of the complexes strongly depends on a surfactant-to-gold molar ratio. At certain molar ratios, particle self-assembly into nanochains and their aggregation have been registered. At higher surfactant concentrations, the surface charge of nanoparticles turned positive, attributed to the formation of the stabilizing double layer of azobenzene surfactants on gold nanoparticle surfaces. These gold-surfactant complexes remained colloidally stable. UV light induced trans-cis isomerization of azobenzene surfactant molecules and thus perturbed the stabilizing surfactant shell, causing nanoparticle aggregation. The results obtained with silver and silicon nanoparticles mimick those for the comprehensively studied gold nanoparticles, corroborating the proposed model of complex formation. In the second part, the interaction between plasmonic metal nanoparticles (Au, Ag, Pd, alloy Au-Ag, Au-Pd), as well as silicon nanoparticles, and cis-isomers of azobenzene containing compounds is addressed. Cis-trans thermal isomerization of azobenzenes was enhanced in the presence of gold, palladium, and alloy gold-palladium nanoparticles. The influence of the surfactant structure and nanoparticle material on the azobenzene isomerization rate is expounded. Gold nanoparticles showed superior catalytic activity for thermal cis-trans isomerization of azobenzenes. In a joint project with theoretical chemists, we demonstrated that the possible physical origin of this phenomenon is the electron transfer between azobenzene moieties and nanoparticle surfaces. In the third part, complexes between gold nanorods and azobenzene surfactants with different tail length were exposed to UV and blue light, inducing trans-cis and cis-trans isomerization of surfactant, respectively. At the same time, the position of longitudinal plasmonic absorption maximum of gold nanorods experienced reversible shift responding to the changes in local dielectric environment. Surface plasmon resonance condition allowed the estimation of the refractive index of azobenzene containing surfactants in solution. N2 - Das Ziel dieser Arbeit ist mit der Fragestellung verwandt, wie plasmonische und photoschaltende Eigenschaften in Nano-Objekten simultan herbeigeführt und kombiniert werden können. Diese Arbeit untersucht Komplexe aus Edelmetall-Nanoteilchen und kationischen Tensiden, deren hydrophober Teil Azobenzol enthält, mithilfe von Absorptionsspektroskopie, Oberflächen-Zeta-Potentialen und Elektronenmikroskopie. Im Teil 1 wird die Bildung von Komplexen aus negativ geladenen, Laser ablatierten, sphärischen Goldnanopartikeln und kationischen Azobenzol-haltigen Tensiden in trans-Konfiguration untersucht. Es wird gezeigt, dass die Zusammensetzung des Komplexes stark vom Tensid-Gold Molverhältnis abhängt. Bei bestimmten Molverhältnissen wurde beobachtet, dass sich die Partikel selbst zu Nanoketten zusammensetzten und aggregieren. Bei höheren Tensid-Konzentrationen wurde die Oberflächen-Ladung der Nanopartikel positiv, erklärt durch das Formen einer stabilen Doppel-Schicht von azobenzolhaltigen Tensiden auf der Gold-Oberfläche. Diese Gold-Tensidkomplexe bleiben kolloidal stabil. UV-Licht induziert eine Trans-Cis Isomerisation von Azobenzoltensidmolekülen und stört somit die stabilisierenden Tensidhüllen, welche die Nanopartikelaggregation bewirken. Die Ergebnisse der Silber- und Silikonnanopartikel decken sich mit den Ergebnissen der ausführlich untersuchten Goldnanopartikel, was den vorgeschlagenen Mechanismus der Komplexbildung bekräftigt. Im Teil 2 wird die Wechselwirkung zwischen plasmonischen Metallnanopartikeln und Cis-Isomeren der Azobenzol beinhaltenden Verbindungen adressiert. Die Studie beinhaltet Gold, Silber, Palladium, Gold-Silber und Gold-Palladium Legierungen, und außerdem Silikonnanopartikel, und eine Serie von Azobenzol-Derivaten. Cis-Trans thermale Isomerisation von Azobenzolen wurde verbessert in der Gegenwart von Gold, Palladium und Gold-Palladium legierten Nanopartikeln. Der Einfluss der Tensidstruktur und Nanopartikelmaterialien auf die Isomerisationsrate wird erläutert. Goldnanopartikel zeigen eine hervorragende katalytische Aktivität für die thermale Cis-Trans Isomerisation von Azobenzolen. In einem gemeinsamen Projekt mit Theoretischen Chemikern haben wir demonstriert, dass ein möglicher Mechanismus der Elektronentransfer von der absorbierten Azobenzolhälfte zur Goldoberfläche ist. Im Teil 3 werden die Komplexe zwischen Goldnanostäbchen und Azobenzol-haltigen Timethylammoniumbromide mit verschiedenen Endlängen UV-Licht und blauem Licht ausgesetzt, was eine Trans-Cis und Cis-Trans Isomerisation von Tensiden induziert. Zur gleichen Zeit erfährt das longitudinale plasmonische Absorptionsmaximum von Goldnanostäbchen eine reversible Verschiebung als Reaktion auf die Änderungen in der lokalen dielektrischen Umgebung. Die Oberflächenplasmonenresonanzbedingung erlaubte die Bestimmung des Brechungsindex von Azobenzol-haltigen Tensiden in wässeriger Lösung. KW - azobenzene surfactant KW - Azobenzol-haltiges Tensid KW - plasmon nano-particles KW - plasmonische Nanopartikeln KW - catalytic azobenzene isomerization KW - katalytische Isomerisation von Azobenzolen KW - azobenzene refractive index KW - Brechungsindex von Azobenzol-haltigen Tensiden KW - азобензолсодержащие ПАВ KW - плазмонные наночастицы KW - каталитическая изомеризация азобензолов KW - показатель преломления азобензолов Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-403359 ER - TY - JOUR A1 - Kasyanenko, Nina A1 - Lysyakova, Liudmila A1 - Ramazanov, Ruslan A1 - Nesterenko, Alexey A1 - Yaroshevich, Igor A1 - Titov, Evgenii A1 - Alexeev, G. A1 - Lezov, Andrey A1 - Unksov, I. T1 - Conformational and Phase Transitions in DNA-Photosensitive Surfactant Solutions: Experiment and Modeling JF - Biopolymers N2 - DNA binding to trans- and cis-isomers of azobenzene containing cationic surfactant in 5 mM NaCl solution was investigated by the methods of dynamic light scattering (DLS), low-gradient viscometry (LGV), atomic force microscopy (AFM), circular dichroism (CD), gel electrophoresis (GE), flow birefringence (FB), UV-Vis spectrophotometry. Light-responsive conformational transitions of DNA in complex with photosensitive surfactant, changes in DNA optical anisotropy and persistent length, phase transition of DNA into nanoparticles induced by high surfactant concentration, as well as transformation of surfactant conformation under its binding to macromolecule were studied. Computer simulations of micelles formation for cis- and trans-isomers of azobenzene containing surfactant, as well as DNA-surfactant interaction, were carried out. Phase diagram for DNA-surfactant solutions was designed. The possibility to reverse the DNA packaging induced by surfactant binding with the dilution and light irradiation was shown. (c) 2014 Wiley Periodicals, Inc. Biopolymers 103: 109-122, 2015. KW - DNA-surfactant complexes KW - light-induced DNA de-compaction KW - phase diagram KW - DNA volume and persistent length Y1 - 2015 U6 - https://doi.org/10.1002/bip.22575 SN - 0006-3525 SN - 1097-0282 VL - 103 IS - 2 SP - 109 EP - 122 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Lysyakova, Liudmila A1 - Lomadze, Nino A1 - Neher, Dieter A1 - Maximova, Ksenia A1 - Kabashin, Andrei V. A1 - Santer, Svetlana T1 - Light-Tunable Plasmonic Nanoarchitectures Using Gold Nanoparticle-Azobenzene-Containing Cationic Surfactant Complexes JF - The journal of physical chemistry : C, Nanomaterials and interfaces N2 - When arranged in a proper nanoaggregate architecture, gold nanoparticles can offer controllable plasmon-related absorption/scattering, yielding distinct color effects that depend critically on the relative orientation and distance between nanoparticle constituents. Herein, we report on the implementation of novel plasmonic nanoarchitectures based on complexes between gold nanoparticles and an azobenzene-modified cationic surfactant that can exhibit a light-tunable plasmonic response. The formation of such complexes becomes possible through the use of strongly negatively charged bare gold nanoparticles (similar to 10-nm diameter) prepared by the method of laser ablation in deionized water. Driven by electrostatic interactions, the cationic surfactant molecules attach and form a shell around the negatively charged nanoparticles, resulting in neutralization of the particle charge or even overcompensation beyond which the nanoparticles become positively charged. At low and high surfactant concentrations, Au nanoparticles are negatively and positively charged, respectively, and are represented by single species due to electric repulsion effects having absorption peaks around 523-527 nm, whereas at intermediate concentrations, the Au nanoparticles become neutral, forming nanoscale 100-nm clusterlike aggregates and exhibiting an additional absorption peak at gimel > 600 nm and a visible change in the color of the solution from red to blue. Because of the presence of the photosensitive azobenzene unit in the surfactant tail that undergoes trans-to-cis isomerization under irradiation with UV light, we then demonstrate a light-controlled nanoclustering of nanoparticles, yielding a switch in the plasmonic absorption band and a related change in the solution color. The formed hybrid architectures with a light-controlled plasmonic response could be important for a variety of tasks, including biomedical, surface-enhanced Raman spectroscopy (SERS), data transmission, and storage applications. Y1 - 2015 U6 - https://doi.org/10.1021/jp511232g SN - 1932-7447 VL - 119 IS - 7 SP - 3762 EP - 3770 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Titov, Evgenii A1 - Lysyakova, Liudmila A1 - Lomadze, Nino A1 - Kabashin, Andrei V. A1 - Saalfrank, Peter A1 - Santer, Svetlana T1 - Thermal Cis-to-Trans Isomerization of Azobenzene-Containing Molecules Enhanced by Gold Nanoparticles: An Experimental and Theoretical Study JF - The journal of physical chemistry : C, Nanomaterials and interfaces N2 - We report on the experimental and theoretical investigation of a considerable increase in the rate for thermal cis -> trans isomerization of azobenzene-containing molecules in the presence of gold nanopartides. Experimentally, by means of UV vis spectroscopy, we studied a series of azobenzene-containing surfactants and 4-nitroazobenzene. We found that in the presence of gold,nanoparticles the thermal lifetime of the cis isomer of the azobenzenecontaining molecules was decreased by up to 3 orders of magnitude in comparison to the lifetime in solution without nanoparticles. The electron transfer between azobenzene-containing molecules and a surface of gold nanopartides is a possible reason to promote the thermal cis trans switching. To investigate the effect of electron attachment to, and withdrawal from, the azobenzene-containing molecules on the isomerization rate, we performed density functional theory calculations of activation energy barriers of the reaction together with Eyring's transition state theory calculations of the rates for azobenzene derivatives with donor and acceptor groups in para position of one of the phenyl rings, as well as for one of the azobenzene-containing surfactants. We found that activation barriers are greatly lowered for azobenzene-containing molecules, both upon electron attachment and withdrawal, which leads, in turn, to a dramatic increase in the thermal isomerization rate. Y1 - 2015 U6 - https://doi.org/10.1021/acs.jpcc.5b02473 SN - 1932-7447 VL - 119 IS - 30 SP - 17369 EP - 17377 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Zakrevskyy, Yuriy A1 - Kopyshev, Alexey A1 - Lomadze, Nino A1 - Morozova, Elena A1 - Lysyakova, Liudmila A1 - Kasyanenko, Nina A1 - Santer, Svetlana T1 - DNA compaction by azobenzene-containing surfactant JF - Physical review : E, Statistical, nonlinear and soft matter physics N2 - We report on the interaction of cationic azobenzene-containing surfactant with DNA investigated by absorption and fluorescence spectroscopy, dynamic light scattering, and atomic force microscopy. The properties of the surfactant can be controlled with light by reversible switching of the azobenzene unit, incorporated into the surfactant tail, between a hydrophobic trans (visible irradiation) and a hydrophilic cis (UV irradiation) configuration. The influence of the trans-cis isomerization of the azobenzene on the compaction process of DNA molecules and the role of both isomers in the formation and colloidal stability of DNA-surfactant complexes is discussed. It is shown that the trans isomer plays a major role in the DNA compaction process. The influence of the cis isomer on the DNA coil configuration is rather small. The construction of a phase diagram of the DNA concentration versus surfactant/DNA charge ratio allows distancing between three major phases: colloidally stable and unstable compacted globules, and extended coil conformation. There is a critical concentration of DNA above which the compacted globules can be hindered from aggregation and precipitation by adding an appropriate amount of the surfactant in the trans configuration. This is because of the compensation of hydrophobicity of the globules with an increasing amount of the surfactant. Below the critical DNA concentration, the compacted globules are colloidally stable and can be reversibly transferred with light to an extended coil state. Y1 - 2011 U6 - https://doi.org/10.1103/PhysRevE.84.021909 SN - 1539-3755 VL - 84 IS - 2 PB - American Physical Society CY - College Park ER -