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Tallosy S.P.,University of Szeged | Janovak L.,University of Szeged | Nagy E.,University of Szeged | Deak A.,University of Szeged | And 4 more authors.
Applied Surface Science | Year: 2016

The aim of this study was to develop photoreactive surface coatings, possessing antibacterial properties and can be activated under visible light illumination (λmax = 405 nm) using LED-light source. The photocatalytically active titanium dioxide (TiO2) was functionalized with silver nanoparticles (Ag NPs) and immobilized in polyacrylate based nanohybrid thin film in order to facilitate visible light activity (λAg/TiO2,max = 500 nm). First, the photocatalytic activity was modelled by following ethanol vapor degradation. The plasmonic functionalization resulted in 15% enhancement of the activity compared to pure TiO2. The photoreactive antimicrobial (5 log reduction of cfu in 2 h) surface coatings are able to inactivate clinically relevant pathogen strains (methicillin resistant Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa) within short time (60-120 min) due to the formed and quantified reactive oxygen species (ROS). The existence of electrostatic interactions between the negatively charged bacteria (from-0.89 to-3.19 μeq/109 cfu) and positively charged photocatalyst particles (in the range of +0.38 and +12.3 meq/100 g) was also proven by charge titration measurements. The surface inactivation of the bacteria and the photocatalytic degradation of the cell wall component were also confirmed by fluorescence and transmission electron microscopic observations, respectively. According to the results an effective sterilizing system and prevention strategy can be developed and carried out against dangerous microorganisms in health care. © 2016 Elsevier B.V. All rights reserved.

Csapo E.,MTA SZTE Supramolecular and Nanostructured Materials Research Group | Sebok D.,MTA SZTE Supramolecular and Nanostructured Materials Research Group | Makrai Babic J.,University of Zagreb | Supljika F.,University of Zagreb | And 5 more authors.
Journal of Dispersion Science and Technology | Year: 2014

Gold nanoparticles reduced by sodium citrate (d ∼ 10 nm) and purchased gold colloid particles (d ∼ 500 nm) were examined and compared. The properties of both gold particles and their biofunctionalized derivatives with L-cysteine and L-glutathione were studied in the presence of sodium nitrate. The structural investigations indicated an aggregated inner structure. The isoelectric points of pure gold, citrate reduced gold, and functionalized gold were measured and compared. The low isoelectric point of pure gold/water interface was explained by considering the distribution and accumulation of H+ and OH- ions within the interfacial water layer, being more pronounced for OH- ions. © 2014 Copyright Taylor & Francis Group, LLC.

Zaccaria F.,VU University Amsterdam | Paragi G.,VU University Amsterdam | Paragi G.,MTA SZTE Supramolecular and Nanostructured Materials Research Group | Fonseca Guerra C.,VU University Amsterdam
Physical Chemistry Chemical Physics | Year: 2016

The alkali metal ion affinity of guanine quadruplexes has been studied using dispersion-corrected density functional theory (DFT-D). We have done computational investigations in aqueous solution that mimics artificial supramolecular conditions where guanine bases assemble into stacked quartets as well as biological environments in which telomeric quadruplexes are formed. In both cases, an alkali metal cation is needed to assist self-assembly. Our quantum chemical computations on these supramolecular systems are able to reproduce the experimental order of affinity of the guanine quadruplexes for the cations Li+, Na+, K+, Rb+, and Cs+. The strongest binding is computed between the potassium cation and the quadruplex as it occurs in nature. The desolvation and the size of alkali metal cations are thought to be responsible for the order of affinity. Until now, the relative importance of these two factors has remained unclear and debated. By assessing the quantum chemical 'size' of the cation, determining the amount of deformation of the quadruplex needed to accommodate the cation and through the energy decomposition analysis (EDA) of the interaction energy between the cation and the guanines, we reveal that the desolvation and size of the alkali metal cation are both almost equally responsible for the order of affinity. © the Owner Societies 2016.

Abraham N.,MTA SZTE Supramolecular and Nanostructured Materials Research Group | Csapo E.,MTA SZTE Supramolecular and Nanostructured Materials Research Group | Bohus G.,MTA SZTE Supramolecular and Nanostructured Materials Research Group | Dekany I.,MTA SZTE Supramolecular and Nanostructured Materials Research Group | Dekany I.,University of Szeged
Colloid and Polymer Science | Year: 2014

The understanding of the interaction of nanoparticles with cell membranes and the penetration of these nano-objects through cell wall is highly required for their biomedical application. In this work were aimed at the study of the interaction of gold nanoparticles with model phospholipid membranes prepared at the air/water interface in a Langmuir trough. Spherical (10 and 15 nm mean diameter) and rod-like gold (aspect ratio: 2.8) nanoparticles were synthesized and biofunctionalized with l-cysteine and l-glutathione. The gold nanoparticles were characterized by TEM images and UV-Vis absorbance measurements. The interaction of the biofunctionalized gold nanoparticles with the model monolayer membrane was studied by surface pressure versus surface area compressional isotherms and by the measurement of the change in surface pressure of a preformed model membrane. The effect of the initial surface pressure of the preformed membrane was evaluated to determine the maximum insertion pressure and synergy. We have found that the driving forces of the bioconjugated Au nanoparticle (NP) or Au nanorod (NR) penetration into the monolayer membrane is mostly determined by electrostatic interaction and orientational van der Waals forces. Monolayer films were transferred with Langmuir-Blodgett technique onto solid substrates and the nanoparticles were visualized with AFM technique. [Figure not available: see fulltext.] © 2014 Springer-Verlag Berlin Heidelberg.

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