Preparation and Characterization of Poly(D,L-Lactide-co-Glycolide) Nanoparticles Containing Ascorbic Acid

This paper is covering new, simplistic method of obtaining the system for controlled delivery of the ascorbic acid. Copolymer poly (D,L-lactide-co-glycolide) (DLPLG) nanoparticles are produced using physical method with solvent/nonsolvent systems where obtained solutions were centrifuged. The encapsulation of the ascorbic acid in the polymer matrix is performed by homogenization of water and organic phases. Particles of the DLPLG with the different content of ascorbic acid have different morphological characteristics, that is, variable degree of uniformity, agglomeration, sizes, and spherical shaping. Mean sizes of nanoparticles, which contain DLPLG/ascorbic acid in the ratio 85/150%, were between 130 to 200 nm depending on which stereological parameters are considered (maximal diameters Dmax, feret X, or feret Y). By introducing up to 15% of ascorbic acid, the spherical shape, size, and uniformity of DLPLG particles are preserved. The samples were characterized by infrared spectroscopy, scanning electron microscopy, stereological analysis, and ultraviolet spectroscopy

Nanostructured relief to orient liquid crystals materials

Electrooptical nematic liquid crystal (LC) cells, which can be used as laser switching devices, electrically and optically addressed spatial light modulators, and analogs of display elements, mostly operate in S and T configurations, which realize a planar orientation of the LC mesophase on the aligning substrate surface. However, the solution of some problems, where the initial black field is necessary for the regime of light transmission through the cell structure, requires a homeotropic alignment of LC molecules on the substrate. In the present paper the possibility of obtaining homeotropic orientation in thin film nematic liquid crystal cells using carbon nanotubes is considered. The results of this investigation can be used to develop optical elements for displays with vertical orientations of NLC molecules (MVA-display technology)

Nanostructured materials for optoelectronic applications

Study and optimization of new nanoscale materials useful for optoelectronic application have been considered. The search for the effective nanostructured materials has been revealed in two directions: to optimize the mechanical hardness of the inorganic systems and to increase the photorefractive parameters of the organics with nanoobjects. It has been testified that the surface mechanical properties of the inorganic materials via nanotubes treatment process can be drastically improved. For example, the surface mechanical hardness of the UV and IR range soft materials can be increased up to 3-10 times under the conditions of oriented nanotubes placement. It has been obtained that the nonlinear optical characteristics (nonlinear refraction n2 and cubic nonlinearity x(3)) of the organics thin films sensitized with fullerenes or nanotubes can be increased up to 3-4 orders of magnitude in comparison with the same parameters for bulk materials traditionally used for nonlinear optics.Selected papers presented at the Eleventh Annual Conference of the Materials Research Society of Serbia, YUCOMAT 200

Dynamic Mechanical Properties of Aramid Fabrics Impregnated with Carbon Nanotube/Poly (Vinyl Butyral)/Ethanol Solution

In this study six samples of polyurethane/p-aramid multiaxial fabric forms (Colon fabrics) were coated with 10 wt.% poly (vinyl butyral) (PVB)/ethanol solution with the addition of multiwalled carbon nanotubes (MWCNT). The solution was impregnated on both sides of each of the fabrics. All composite samples consisted of four layers of the impregnated fabrics. The MWCNT/PVB content was 0, 0.1 and 1 wt.%. The three samples of the fabrics with different MWCNT/PVB content were coated with γ-aminopropyltriethoxysilane (AMEO silane)/ethanol solution due to the surface modification. The mechanical properties of the prepared composite samples were studied by dynamic mechanical analysis (DMA). The 60% increase in storage modulus was achieved by addition of MWCNT and impregnation of aramid fabrics with AMEO silane. The pristine multiwalled carbon nanotubes (MWCNT) were introduced in order to enhance additionally the mechanical properties of the materials for ballistic protection

Influence of the nanostructure on the surface and bulk physical properties of materials

Fullerenes, nanotubes, quantum dots have been considered as effective sensitizers to modify both the spectral, optical, nonlinear optical features, dynamic and polarization characteristics, as well as mechanical properties of the organic and inorganic materials. Laser, spectroscopy, mass-spectroscopy, nuclear magnetic resonance methods have been apply to support the change in the physical properties of the new nanocomposites. The extending of the nanocomposites applications area has been considered

Nanostructured materials for optoelectronic applications

New way to improve the surface properties of the inorganic and organic materials via nanotubes treatment process has been shown. It has been testified that the surface mechanical hardness of the MgF2, LiF, etc. materials can be increased up to 3-10 times under the conditions of the spectral range keeping. Some simple model to explain the results has been discussed. As an additional, some features of transparent conducting ITO contacts modified with surface electromagnetic waves have been found. The data presented in the current paper testified that these nano-objects-optimized materials could be used as new elements and new laser window for the UV and IR spectral range

Evaluation compensation of an osteoporotic rat bone with Ca/Co-HAp nanoparticles

This study examined the role of Ca / Co-HAp nanoparticles on time distance in regeneration of osteoporotic alveolar bone in rats by biochemical blood markers analysis (ALP, Ca, Mg, P) and through histochemical analysis. The research was carried out on female Westar rats, aged 6-8 weeks. The obtained results for the biochemical blood markers showed statistically significant rise. Histological analysis revealed high level reparatory skills of the biocomposite implanted in the bone defect as early as in the mineralized tissues. It can be concluded that Ca/Co-HAp stimulates the regeneration of osteoporotic alveolar bone in tested animals as confirmed by the increased levels of biochemical blood markers and through histochemical analysis. Therefore, it can be concluded that Ca/Co-HAp nanocomposite should be choise material in the osteoconstructive processes in the future

Testing the antimicrobial activity of hydroxyapatite nanoparticles in vitro

Antimicrobial materials based on hydroxyapatite are very attractive for wide application in medicine and stomatology. The goal of this work was to test antimicrobial activity of hydroxyapatite nanoparticles Co/Ca- hydroxyapatite and biphasic calcium phosphate/ poly (lactide-co-glycolide) composite biomaterial. Antimicrobial activity of the samples was tested using dilution method and disk diffusion. The results of antimicrobial tests were obtained by determining the reduction percentage the number of bacteria in physiological solution where bacteria cells were exposed to the samples. It can be concluded that synthesized HAp biomaterials have satisfactory antimicrobial activity against tested bacteria strains

In vitro evaluation of antimicrobial activity of nano composite biomaterials based on hydroxyapatite

Antimicrobial materials based on hydroxyapatite are potentially attractive in a wide variety of medical and stomatological applications. The objective of this paper is to examine antimicrobic activity of cobalt-substituted calcium hydroxyapatite nanopowders and biphased calciumphosphate/ poli-lactide-co-glicolide. The antimicrobial effects of these substances (powders) against two pathogen bacterial strains- Escherichia coli (ATCC 25922) and Staphylococcus aureus (ATCC 25923) were tested by disc diffusion method and quantitative antimicrobial test in liquid medium. It was noted that the inhibition zone of the bacterial cells S. aureus around the sample of the Ca/Co- HAp, was a lot bigger compared to the inhibition zone of bacterial cells E. coli around the sample of the mentioned biomaterial, which means that this material has bigger antimicrobic activity on S. aureus, in relation to E. coli. Quantitative antimicrobial test in liquid medium demonstrate that cobalt-substituted calcium hydroxyapatite samples show viable cells reduction of both tested microorganisms. It may be concluded that nanoparticles of cobalt-substituted calcium hydoxyapatite nano-powders has a satisfactory antimicrobic activity according to the tested bacteria strain