Dionezie Bojin

Effect of UV Sunscreens Loaded in Solid Lipid Nanoparticles: A Combinated SPF Assay and Photostability

The aim of this investigation was to obtain lipid nanoparticles loaded with different sunscreen agents in order to achieve enhanced photoprotection and to decrease the amount of UV – absorbers, with preserving at the same time a high sun protection factor. The developed formulations combined different types of additives including a mixture of non-ionic surfactant and lechitine with two lipids as solid matrix to obtain favourable stable lipid formulations. The research work could be concluded as successefully production of lipid nanoparticles loaded with UV-A and UV-B absorbers (with average size less than 100 nm) that may represent useful UV-blocking systems in sunscreen products for cosmetical purpose.

Antioxidant Activity of Solid Lipid Nanoparticles Loaded with Umbelliferone

The objective of this investigation was to develop solid lipid nanoparticles (SLNs) of umbelliferone by means of a high shear homogenization technique and to evaluate the efficiency of SLN systems in preserving and enhancing antioxidant activity of the flavonoid active component. The aqueous SLN dispersions combine two structural types of lipid compounds and different types of emulsifiers including a mixture of monoalkyl polyoxyethylene sorbitan with a block copolymer and lecithin. The assessment of umbelliferone stability in aqueous SLN dispersions, the size distribution of lipid nanoparticles loaded with umbelliferone (by DLS technique), as well as the structural changes (FT-IR spectroscopy and differential scanning calorimetry) of these lipid nanomatrices have been investigated. Moreover, the influence of umbelliferone concentration onto entrapment efficiency and antioxidant properties were clearly evidenced on four kinds of lipid nanoparticles. The umbelliferone-loaded SLN prepared with polyethylene glycol sorbitan monostearate shown a mean particle size of 173.4 nm ± 3.279, as well as good entrapment efficiency (EE = 60.70%) and antioxidant properties (AA = 75%).

New laser ablation chamber for producing carbon nanomaterials using excimer laser

Abstract Carbon nanomaterials have been obtained using an innovative laser ablation chamber design. The chamber has several improvements of the design including a longer oven and a longer cold finger as compared to other designs. The laser employed in these experiments has been a KrF excimer laser. The chamber has been successfully used for obtaining nano-onions and single walled carbon nanotubes by laser ablation. A novel target preparation method has been developed and employed to incorporate metal catalysts without the need of pressing or hot pressing of the targets. The ablation products, obtained using this new chamber design, have been investigated by transmission electron microscopy and micro-Raman spectroscopy, as well as thermogravimetric analysis measurements.

Synthesis of single-wall carbon nanotubes by excimer laser ablation

We report the KrF excimer laser ablation of carbonaceous targets in an innovative laser ablation chamber. The targets have been prepared using a new approach, without pressing or hot pressing of the composition. The Co/Ni doped target has yielded single-wall carbon nanotubes with a narrow diameter distribution. High-resolution transmission electron microscopy has been used along with the confocal Raman microscopy to characterize the products obtained. Thermogravimetric analysis confirms the presence of multiple carbonaceous species with different oxidation temperatures.

Antioxidant Capacity of Lipid Nanoparticles Loaded with Rosemary Extract

This work presents a simple, available and effective method for preparation of lipid nanoparticles loaded with a natural extract containing active principles. The purpose of the research is to synthesize new lipid nanoparticles with enhanced antioxidant activity, by using two types of lipid carriers. The lipid nanoparticles were produced by emulsification with high shear homogenisation method using biocompatible emulsifiers with excellent skin compatibility as surfactants. The developed nanoparticles were characterized for particle size, polydispersity index, zeta potential, morphology, crystallinity of the lipid matrices and antioxidant activity. Both types of synthesized lipid nanoparticles exhibit an improved antioxidant activity.

Pulse laser ablation system for carbon nano-onions fabrication

A new laser ablation chamber design for KrF excimer laser synthesis of carbon nanomaterials, including nano-onions, is reported. The conditions for carbon nano-onions deposition, using excimer laser to ablate a commercial pure graphite target, were investigated. The transmission electron microscopy analysis of the collected deposits indicates that mainly nano-onions are obtained when pure graphite targets are ablated. Raman spectroscopy identified without doubt production of carbon nano-onions.

Role of silsesquioxane compounds used as 'building blocks' in sol–gel nanoencapsulation of retinyl palmitate

Abstract The aim of paper is focused on development of novel alternative solutions in order to realise a combination of sensitive molecules with rigid support materials. In this context, a new class of silica precursors based on bridge bonded silsesquioxane organised into periodic mesoporous architecture is suitable for this purpose. A silsesquioxane incompletely condensed (dimethylvinylsilyloxy)-heptacyclo-pentyltricycloheptasiloxanediol) has been selected for sol–gel bioentrapment of retinyl palmitate, in an approach based on high biocompatibility and mild sol–gel encapsulation conditions which enables the reproducible and efficient confinement of retinyl palmitate inside silica. For entrapping of retinyl palmitate within cage structure a templating agent was used, n-dodecyl-β-D-maltoside. The process used for retinyl palmitate encapsulation in silsesquioxane matrix consisted in two main steps: the first step was the synthesis of glucosidal template silica materials, and the second was the encapsulation of retinyl palmitate into silica silsesquioxane network.

Biomimetic Hybrid Inorganic/Organic Coatings in the Increasing of the Integration Capacity of TiAlVZr Bioalloy

This paper will address key issues related to the synthesis, characterization and utilization of inorganic/organic hybrid coatings on TiAlVZr bioalloy to control adsorption at interface and the integration capacity of the implant. To enhance the integration capacity function of the biomaterial is necessary to control the composition and structure via the use of hybrid materials consisting of organic and inorganic biomimetic phases [1,2]. Such composite coatings mimic the structure of natural materials of tissues, in our case hydroxyapatite (HA) by association of bovine serum albumin (BSA) with calcium phosphates matrices. Calcium phosphate coating have been deposited on metal substrates by electrochemical method.

Wetting properties of glycerol on silicon, native SiO2, and bulk SiO2 by scanning polarization force microscopy

Scanning polarization force microscopy, a relatively new non-contact scanning probe microscopy technique, was applied in order to investigate the properties of liquid surfaces (droplets), such as: topography, microscopic contact angle θ, surface potential energy P(e), spreading coefficient S, and disjoining pressure П. Investigations were carried out on glycerol droplets deposited on surfaces of bare silicon, silicon covered with native oxide, and bulk silicon oxide. Contact angle values were determined from directly measured topography profiles of micro- and nanodroplets. Values of surface potential energy, spreading coefficient, and disjoining pressure were calculated based on a model of the dependence of contact angle on droplet height. The results of these experiments offer valuable insights into the mechanisms of wetting phenomena at the microscopic scale.

Krypton gas for high quality single wall carbon nanotubes synthesis by KrF excimer laser ablation

We report for the first time the production of single wall carbon nanotubes (SWCNTs) by KrF excimer laser ablation method under the krypton gas atmosphere. For the ablation experiment 450 mJ energy and 30 Hz repetition rate KrF excimer laser was used, and the target was prepared with the following composition: 0.6% Ni, 0.6% Co, and 98.8% C (atomic percentage). The ablation product was characterized by confocal Raman microspectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The SWCNTs obtained are a mixture of semiconducting and metallic types with narrow diameters distribution of 1.26 to 1.49 nm, are micrometers long, and contain low amount of graphite and amorphous carbon.