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The possibility of one-step creating of pH-sensitive mesostructured silica-based nanocontainers with exceptionally high payload using associates of two antiseptics (including hydrolyzable one) as templates is demonstrated. The effects of the template nature and the conditions of the sol-gel process on the porous structure of silica nanocontainers are studied and discussed. The kinetics of the templating drug release from such containers is studied and some features of this process are analyzed. It is shown that the drug release rate can be tuned by varying the medium pH. The bactericidal activity of two encapsulated antiseptics against the Staphylococcus aureus is evaluated in vitro by agar diffusion method with replacement of agar with agarose. The diameters of the inhibition zones for silica-based containers loaded with antiseptics increased with the pre-diffusion time at 4 °C. At the same time, empty containers (after elimination of antiseptics by etching) did not reveal any bactericidal properties., (Copyright © 2019 Elsevier B.V. All rights reserved.)

A comparative analysis has been performed for the structure of ring deposits resulting from the evaporation of droplets of aqueous dispersions of gold nanorods and composite nanoparticles with a gold core/organosilica shell structure based thereon. The nature of the particles has been shown to have a key effect on the character of their packing near a three-phase contact line. The study of the conductivity of the ring deposits obtained from dispersions of the composite particles has shown that it is realized via over-barrier electron emission. [ABSTRACT FROM AUTHOR]

The effect of the plasmonic enhancement of dye fluorescence in poly(vinyl butyral) films containing Ag/SiO2 core-shell nanoparticles has been thoroughly studied. It has been shown that the magnitude of this effect can be quite large (up to 5 times) even for a dye having a very high quantum yield (coumarin 7). Therewith, it substantially depends on the size and concentration of Ag/SiO2 particles and the quantum yield of a dye. The results obtained are discussed with involvement of mechanisms reported in the literature for plasmonic enhancement of fluorescence of dyes characterized by high and low quantum yields. [ABSTRACT FROM AUTHOR]

Abstract: The effect of the degree of anisotropy (axial ratio) of gold nanoparticles on the structure and conductivity of ring deposits formed on a planar substrate upon evaporation of droplets of aqueous dispersions with different particle number concentrations has been studied. A nontrivial phenomenon of a decrease in the specific conductivity of the deposits with an increase in particle concentration in case of gold nanorods dispersions has been revealed. [ABSTRACT FROM AUTHOR]

A new method has been proposed for designing composite materials that represent highly ordered two-dimensional metal nanoparticles ensembles having variable geometric parameters and being embedded into the surface layer of a polymer matrix to a predetermined depth. The method is based on diblock copolymer micellar lithography and the effect of decreased glass-transition temperature of a polymer surface as compared with its bulk value. The possibility of independent variations in the depth of embedding of metal nanoparticles (by system annealing) and their size (by seeded growth) has resulted in the systematic study of the influence of the temperature and time of annealing on the kinetics of nanoparticle embedding into a polymer. For the first time, the plasmon-resonant properties of hexagonally ordered ensembles of gold nanoparticles located at a polymer-air interface have been experimentally studied. It has been established that the embedding of an ensemble of nanoparticles into a polymer is accompanied by a bathochromic shift of the maximum of its localized surface plasmon resonance due to a growth in the effective dielectric permittivity of the environment of the nanoparticles. An empirical equation has been proposed, which satisfactorily describes these experimental data. [ABSTRACT FROM AUTHOR]

The process of the enlargement of gold hydrosol nanoparticles adsorbed on the surfaces of glassy polymers (polystyrene and poly(2-vinylpyridine)) in mixed aqueous solution of chloroauric acid and hydroxylamine is studied. It is established that the character of this process depends on the intensity of metal-polymer interaction and the density of nanoparticle packing in an initial monolayer. At a high coverage of a poly(2-vinylpyridine) surface by “ seeding” gold particles, their rather uniform growth is observed, whereas, at low coverage, the enlargement of adsorbed particles, as well as the nucleation and growth of new particles take place. At the same time, new Au nanoparticles are not formed on the polystyrene surface in the enlargement process, even at low coverages by preliminarily deposited “seeding” hydrosol particles. Adsorbed gold particles can also be enlarged after their preliminary incorporation into the polystyrene surface layer. Such an incorporation (partial embedding) is ensured by the annealing of a system at a temperature between “surface” (T'g) and “ bulk” glass transition temperatures. In this case, theT'g value can be considerably decreased (up to room temperature) by the addition of small amounts of a homologue with a much lower molecular mass in the polystyrene matrix. Lateral conductivity of colloidal Au films formed on a poly(2-vinylpyridine) surface by the enlargement of adsorbed seeding particles is measured. According to these measurements, contacts providing the formation of conductive channels are formed in the process of nanoparticle enlargement. [ABSTRACT FROM AUTHOR]

The adsorption of gold hydrosol nanoparticles on the surfaces of polystyrene and poly(2-vinylpyridine) was studied using two techniques, quartz crystal microgravimetry and atomic force microscopy. The resultant experimental data indicated that the kinetics of this process is controlled by the diffusion. The nanoparticle adsorption, up to rather high polymer surface coverages (≈35%), is irreversible. [ABSTRACT FROM AUTHOR]

We demonstrated the possibility of preparing continuous silver shells on particles of polystyrene latex by enlarging adsorbed seeding metal nanoparticles in solution containing ascorbic acid and silver nitrate. It is shown that a strong batochromic shift of the maximum of surface plasmon resonance is observed for such composite structures. [ABSTRACT FROM AUTHOR]