Provider: - Institution: - Data provided by Europeana Collections- The borate (C6 and C9,5) and citrate (C17 and C30) capped gold nanoparticles of different average core sizes and properties, were characterized by transmission electron microscopy (TEM), ultraviolet-visible spectroscopy (UV-Vis), fluorescence spectroscopy, Fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS) and zeta potential measurements, in the absence and presence of cyanine dye, sodium (Z)-3-(5-chloro-2-((5-chloro-3-(3-sulfonatopropyl) benzothiazol-2(3H)- ylidene)methyl)benzothiazol-3-ium-3-yl)propane-1-sulfonate (TC) in water conditions, and the obtained results confirmed that TC was adsorbed on the surface of these nanoparticles. The measurements of fluorescence of the particle–dye assembly, corrected for inner filter effects, clearly indicated that the fluorescence of TC was quenched by gold nanoparticles on the concentration dependent manner. This process was found to be quantitatively related to the surface coverage of the Au nanoparticle by TC dye molecules. Significant increase of quenching efficiency was noticed when nanoparticle size increased, keeping the concentration of nanoparticles of different size constant. The experimental results of fluorescence quenching were compared with those obtained by theoretical calculations, in which we assumed that the maximum quenching of TC dye fluorescence was restricted to full monolayer coverage of TC on the nanoparticle surface. In case of C17 and C30 nanoparticles, the experimentally obtained values for nanoparticle concentration needed to completely quench TC dye fluorescence were lower than the calculated ones, while higher experimental values in comparision with calculated ones of quenched TC dye at constant nanoparticle concentration were obtained. These findings leaded to the conclusion that the most probable orientation of TC dye molecules on the surface of these nanoparticle was slanted. On the other hand, in case of C6 and C9,5 nanoparticles, the obtained calculated values for TC concentration needed to cover the nanoparticle surface and be completely quenched, for all three possible orientations of TC dye, were lower in comparision with the experimental values. The experimentally obtained value of C9,5 concentration needed to completely quench TC dye fluorescence most closely corresponds to vertical TC dye orientation along the short side, while the experimentally obtained results in case of C6 nanoparticles were much lower than theoretically calculated values for all three possible TC dye orientations. These findings indicated that on the surface of C6 nanoparticles the dye was accommodated in more than one layer. In addition, from the fluorescence quenching experiments, the equilibrium constants for the sorption of TC on the surface of all mentioned nanoparticles were calculated. TC dye J-aggregate formation, obtained only in the presence of C6 colloidal nanoparticles, as well as kinetics and mechanism of this process were investigated. Thereby, the kinetic and activation parameters of this reaction were determined, and the influence of mono- (Li+, Na+, K+, Cs+), di- (Mg2+) i trivalent (Al3+) metal cations on TC J-aggregation was estimated. Kinetic studies of this hybrid dye/metal nanoparticle Jaggregate formation have shown a two-step process, a fast initial formation of the surface layer, followed by the slower, growth of J-aggregates on the initial TC layer. The adsorption of this negatively charged dye on the surface of negatively charged gold nanoparticles is only possible if the dye molecules are oriented toward the surface of nanoparticles via thiazole sulfur, which carries partial positive charge. This hypothesis is supported by the activation parameters estimated from kinetic data. The presence of Jaggregates was noticed in the prescence of metal ions in TC dye solution, and also after the addition of C6 nanoparticles and in the presence of all mentioned cations except Al3+. The rate constants for faster and slower process of J-aggregate formation decreased with increasing the size of monovalent cations. With increasing temperature, in the presence of Cs+ ions, the values of rate constants for both processes increased, while the obtained calculated lower values of activation energies in comparison with values obtained without their presence indicated that in this case the energy barrier was reduced and the J-aggregate formation was promoted. Two more colloidal dispersions of gold nanoparticles prepared by citrate reduction, namely C15 i C47, were sintetized, and their cytotoxic properties were examined using two in vitro human cells model systems: proliferating lymphocytes and connective tissue fibroblasts. The obtained results indicated the concentration dependent effects in both cases, as well as size dependence, although lymphocytes turned to be more sensitive to gold nanoparticles. Treatment of lymphocyte cultures with these gold nanoparticles caused cytotoxic effects as revealed by significant enhancement of incidence of micronuclei but non significant increase of cell proliferation potential when compared to the control, still suggesting disturbed function of cell-cycle checkpoints. In a fibroblast cell line, the same doses of gold nanoparticles induced the slightly higher level of γ- H2AX foci than in a control.- Primenom više eksperimentalnih metoda (TEM, UV-Vis spektrofotometrija, fluorescentna spektroskopija, FTIR, DLS, merenja zeta potencijala) ispitane su nanočestice zlata različitih svojstava i veličina sa adsorbovanim boratnim (C6 i C9,5) i citratnim (C17 i C30) jonima na površini, u odsustvu i prisustvu TC boje (natrijum-(Z)-3- (5-hlor-2-((5-hlor-3-(3-sulfonatopropil)benzotiazol-2(3H)-iliden)metil)benzotiazol-3- ium-3-il)propan-1-sulfonata) u vodenoj sredini, i potvrđena je adsorpcija TC na površini ovih nanočestica. Merenje fluorescencije agregata čestica-boja, korigovane za efekat unutrašnjeg filtera, je ukazalo da nanočestice zlata, u zavisnosti od koncentracije, gase fluorescenciju TC boje. Nađeno je da je ovaj proces kvantitativno povezan sa stepenom pokrivenosti površine nanočestica zlata molekulima TC boje. Pritom je efikasnost gašenja rasla sa povećanjem veličine čestica, pri čemu je koncentracija nanočestica zlata u rastvoru održavana konstantnom. Uz pretpostavku da je maksimalno gašenje fluorescencije TC boje ograničeno na potpunu monoslojnu pokrivenost površine nanočestica TC bojom (zavisno od orijentacije boje), eksperimentalno dobijene vrednosti koncentracije nanočestica C17 i C30 potrebne za potpuno gašenje fluorescencije TC boje su bile niže od teorijski izračunatih, dok su za gašenje fluorecencije TC boje pri konstantnoj koncentraciji nanočestica dobijene više eksperimentalne vrednosti u poređenju sa teorijski izračunatim, iz čega je zaključeno da je najverovatnija orijentacija molekula TC boje na površini ovih nanočestica kosa. S druge strane, u slučaju nanočestica C6 i C9,5 teorijski dobijene vrednosti za koncentraciju TC boje potrebnu da pokrije površinu nanočestice i da fluorescencija boje bude potpuno ugašena, u slučaju sve tri orijentacije, su niže u poređenju sa dobijenim eksperimentalnim vrednostima. Koncentracija nanočestica C9,5, potrebna da bi došlo do potpunog gašenja fluorescencije TC boje, po vrednosti najpribližnije odgovara vertikalnoj orijentaciji boje duž kraće strane, dok je u slučaju C6 eksperimentalno dobijen rezultat dosta niži od teorijski izračunatih vrednosti za sve tri moguće orijentacije boje, iz čega je zaključeno da je na površini ovih nanočestica boja smeštena u više od jednog sloja. Iz eksperimenata u kojima je ispitivano gašenja fluorescencije, izračunate su i konstante ravnoteže za proces adsorpcije TC na površini svih ispitivanih nanočestica. Ispitano je formiranje J-agregata, dobijenih samo u prisustvu koloida C6, kao i kinetika i mehanizam J-agregacije. Pritom su određeni kinetički i aktivacioni parametri ove reakcije, kao i uticaj jednovalentnih (Li+, Na+, K+, Cs+), dvovalentnih (Mg2+) i trovalentnih (Al3+) metalnih jona na reakciju J-agregacije. Kinetička ispitivanja formiranja hibridnih J-agregata boje u prisustvu ovih nanočestica zlata su pokazala da se reakcija odvija kroz dva koraka, brzo inicijalno formiranje površinskog sloja, koje je praćeno sporijim rastom J-agregata na inicijalnom sloju J-agregata. Adsorpcija ove negativno naelektrisane boje na površini negativno naelektrisanih nanočestica zlata je moguća kada su molekuli boje prema površini nanočestica orijentisani preko tiazolnog sumpora, koji nosi parcijalno pozitivno naelektrisanje, što je u skladu sa aktivacionim parametrima određenim iz kinetičkih podataka. J-agregacija je primećena po dodatku metalnih jona u rastvor boje, a nakon dodatka nanočestica u rastvor boje i u prisustvu svih navedenih jona, osim Al3+, takođe je došlo do formiranja J-agregata. Pritom, sa porastom veličine jednovalentnih katjona dolazi do smanjenja vrednosti konstante brzine i brzog i sporijeg procesa J-agregacije. Sa povišenjem temperature, u prisustvu Cs+, vrednosti konstanti brzina za oba procesa rastu, pri čemu su izračunate niže vrednosti aktivacionih energija u poređenju sa vrednostima dobijenim bez njihovog prisustva ukazale da je u ovom slučaju smanjena energetska barijera i pospešena reakcija J-agregacije. Ispitana su citotoksična svojstva još dve različite koloidne disperzije zlata, C15 i C47, sintetizovane sa citratom kao redukcionim sredstvom, korišćenjem dva in vitro model sistema humanih ćelija: limfocita i fibroblasta. Dobijeni rezultati su pokazali da u oba slučaja postoji koncentraciona zavisnost za različite efekte, kao i zavisnost od veličine čestica, ali je u slučaju limfocita dobijena veća osetljivost na nanočestice zlata. Tretiranje kultura limfocita sa nanočesticama zlata je izazvalo citotoksične efekte koji su pokazani značajnim uvećanjem učestalosti mikronukleusa ali zanemarljivo malim povećanjem ćelijskog proli