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1.
Soft Matter ; 11(34): 6859-65, 2015 Sep 14.
Article in English | MEDLINE | ID: mdl-26235250

ABSTRACT

A "nano-net" superstratum strategy is developed to stabilize layer-by-layer (LbL) films that incorporate nanoparticles. The superstratum immobilizes silica, gold, or magnetic nanoparticles and at the same time is permeable to small molecules. Unlike most strategies to stabilize LbL multilayers reported in the literature, our strategy does not directly cross-link the nanoparticles and polymers in the adjacent layer, thus circumventing the tedious processes of (surface) modification of the nanoparticles or polymers. The unique advantage of our strategy is further employed in the preparation of a model functional device, where mesoporous silica nanoparticles are held in the composite multilayers with enhanced stabilities. A model drug, methylene blue, is then loaded in large amounts due to the porous structure of the silica particles, and could be released in a delayed manner up to 55 h.

2.
IET Nanobiotechnol ; 8(4): 282-9, 2014 Dec.
Article in English | MEDLINE | ID: mdl-25429509

ABSTRACT

The use of silver nanoparticle on various substrates has been widespread because of its good antibacterial properties that directly depend on the stability of the silver nanoparticles in a colloidal suspension. In this study, the colloidal solutions of the silver nanoparticles were synthesised by a simple and safe method by using lecithin as a stabilising agent and their stability was examined at various temperatures. The effect of the lecithin concentrations on the stability of the synthesised silver nanoparticles was examined from 25 to 80°C at 5°C intervals, by recording the changes in the UV-vis absorption spectra, the hydrodynamic diameter and the light scattering intensity of the silver nanoparticles. In addition, the morphology of the synthesised silver nanoparticles was investigated with the low-voltage scanning electron microscopy and transmission electron microscopy. The results indicated that increasing temperature caused different changes in the size of the stabilised and the unstabilised silver nanoparticles. The size of the stabilised silver nanoparticles reduced from 38 to 36 nm during increasing temperature, which confirmed good stability.


Subject(s)
Lecithins/chemistry , Lipid Bilayers/chemistry , Metal Nanoparticles/chemistry , Silver/chemistry , Drug Stability , Particle Size , Temperature
3.
Int J Pharm ; 475(1-2): 270-81, 2014 Nov 20.
Article in English | MEDLINE | ID: mdl-25148730

ABSTRACT

Phenothiazine drugs - chlorpromazine (CPZ), promazine (PZ) and promethazine (PMZ) - were exposed to 266 nm (fourth harmonic of the Nd:YAG pulsed laser radiation) in order to be modified at molecular level and to produce an enhancement of their antibacterial activity. The irradiated samples were analysed by several methods: pH and surface tension measurements, UV-vis-NIR absorption spectroscopy, laser induced fluorescence and thin layer chromatography. The purpose of these investigations was to study and describe the modified properties of the medicines to further investigate their specific interactions with materials such as cotton, polyester and Parafilm M as a model smooth surface. The textile materials may be impregnated with phenothiazines drug solutions exposed to laser radiation in order to be used in treatments applied on the surface of the organism. Some of the phenothiazines solutions exposed prolonged time intervals to laser radiation have much better activity against several bacteria. Therefore, in the paper, it is reported the wetting behaviour of CPZ, PZ and PMZ solutions, irradiated for time intervals between 1 and 240 min, on the surfaces of the three textures in order to draw a conclusion about their wettability as a function of time.


Subject(s)
Phenothiazines/chemistry , Solutions/chemistry , Anti-Bacterial Agents/chemistry , Chlorpromazine/chemistry , Chromatography, Thin Layer/methods , Cotton Fiber , Hydrogen-Ion Concentration , Lasers , Paraffin/chemistry , Polyesters/chemistry , Promazine/chemistry , Promethazine/chemistry , Surface Tension , Wettability
4.
J Mater Sci ; 47(5): 2078-2087, 2012.
Article in English | MEDLINE | ID: mdl-25983345

ABSTRACT

A new approach to functionalize the surface of polyester textiles is described in this study. Functionalization was achieved by incorporating pH/temperature-responsive polyelectrolyte microgels into the textile surface layer using UV irradiation. The aim of functionalization was to regulate polyester wettability according to ambient conditions by imparting stimuli-responsiveness from the microgel to the textile itself. Microgels consisted of pH/thermo-responsive microparticles of poly(N-isopropylacrylamide-co-acrylic acid) either alone or complexed with the pH-responsive natural polysaccharide chitosan. Scanning Electron Microscopy, X-ray Photoelectron Spectroscopy, ζ-potential measurements, and topographical analysis were used for surface characterization. Wettability of polyester textiles was assessed by dynamic wetting, water vapor transfer, and moisture regain measurements. One of the main findings showed that the polyester surface was rendered pH-responsive, both in acidic and alkaline pH region, owing to the microgel incorporation. With a marked relaxation in their structure and an increase in their microporosity, the functionalized textiles exhibited higher water vapor transfer rates both at 20 and 40 °C, and 65% relative humidity compared with the reference polyester. Also, at 40 °C, i.e., above the microgel Lower Critical Solution Temperature, the functionalized polyester textiles had lower moisture regains than the reference. Finally, the type of the incorporated microgel affected significantly the polyester total absorption times, with an up to 300% increase in one case and an up to 80% decrease in another case. These findings are promising for the development of functional textile materials with possible applications in biotechnology, technical, and protective clothing.

5.
Biotechnol J ; 6(10): 1219-29, 2011 Oct.
Article in English | MEDLINE | ID: mdl-21751392

ABSTRACT

This study focuses on a microgel-based functionalization method applicable to polyester textiles for improving their hydrophilicity and/or moisture-management properties, eventually enhancing wear comfort. The method proposed aims at achieving pH-/temperature-controlled wettability of polyester within a physiological pH/temperature range. First, primary amine groups are created on polyester surfaces using ethylenediamine; second, biopolymer-based polyelectrolyte microgels are incorporated using the natural cross-linker genipin. The microgels consist of the pH-responsive natural polysaccharide chitosan and pH/thermoresponsive poly(N-isopropylacrylamide-co-acrylic acid) microparticles. Scanning electron microscopy confirmed the microgel presence on polyester surfaces. X-ray photoelectron spectroscopy revealed nitrogen concentration, supporting increased microscopy results. Electrokinetic analysis showed that functionalized polyester surfaces have a zero-charge point at pH 6.5, close to the microgel isoelectric point. Dynamic wetting measurements revealed that functionalized polyester has shorter total water absorption time than the reference. This absorption time is also pH dependent, based on dynamic contact angle and micro-roughness measurements, which indicated microgel swelling at different pH values. Furthermore, at 40 °C functionalized polyester has higher vapor transmission rates than the reference, even at high relative humidity. This was attributed to the microgel thermoresponsiveness, which was confirmed through the almost 50% decrease in microparticle size between 20 and 40 °C, as determined by dynamic light scattering measurements.


Subject(s)
Acrylamides/chemistry , Chitosan/chemistry , Gels/chemistry , Polyesters/chemistry , Polymers/chemistry , Absorption , Amination , Hydrogen-Ion Concentration , Iridoid Glycosides/chemistry , Iridoids , Light , Microscopy, Electron, Scanning , Microspheres , Polyethylene Glycols/chemistry , Polyethylene Terephthalates , Scattering, Radiation , Temperature , Textiles , Wettability
6.
Langmuir ; 24(20): 11895-901, 2008 Oct 21.
Article in English | MEDLINE | ID: mdl-18798658

ABSTRACT

In this paper, we report on a systematic and thorough study of wetting phenomenon on regularly patterned surfaces fabricated from inorganic-organic hybrid "core-shell" particles of different radii (100 nm to 10 microm). Inorganic silica particles were modified through chemical anchoring of polymers and silanes with different hydrophobicities. Modified "core-shell" particles were assembled into regular hexagonally packed structures. The use of regular structured surfaces with specifically designed surface roughness allowed mathematic prediction of the wetting behavior according to existing models and its comparison with experimental observations. It was shown that the character of the wetting behavior varies with the particles size and the chemical nature of the surface immobilized substance. For the regular particle assemblies, an increase in the vertical roughness was achieved with increasing particle radius, but without changing the Wenzel roughness factor.


Subject(s)
Chemistry, Physical/methods , Surface Properties , Wettability , Crystallization , Equipment Design , Hydrophobic and Hydrophilic Interactions , Models, Statistical , Particle Size , Silanes/chemistry , Silicon/chemistry , Silicon Dioxide/chemistry , Temperature
7.
J Colloid Interface Sci ; 267(2): 456-62, 2003 Nov 15.
Article in English | MEDLINE | ID: mdl-14583223

ABSTRACT

Static and dynamic contact angles of aqueous solutions of three surfactants--anionic sodium dodecyl sulfate (SDS), cationic dodecyltrimethylammonium bromide (DTAB), and nonionic pentaethylene glycol monododecyl ether (C(12)E(5))--were measured in the pre- and micellar concentration ranges on polymer surfaces of different surface free energy. The influence of the degree of substrate hydrophobicity, concentration of the solution, and ionic/nonionic character of surfactant on the drop spreading was investigated. Evaporation losses due to relatively low humidity during measurements were taken into account as well. It was shown that, in contrast to the highly hydrophobic surfaces, contact angles for ionic surfactant solutions on the moderately hydrophobic surfaces strongly depend on time. As far as the nonionic surfactant is considered, it spreads well over all the hydrophobic polymer surfaces used. Moreover, the results obtained indicate that spreading (if it occurs) in the long-time regime is controlled not only by the diffusive transport of surfactant to the expanding liquid-vapor interface. Obviously, another process involving adsorption at the expanding solid-liquid interface (near the three-phase contact line), which goes more slowly than diffusion, has to be active.

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