Search results for "Lipids"
showing 10 items of 2228 documents
Spray freeze drying as an alternative technique for lyophilization of polymeric and lipid-based nanoparticles.
2016
The use of nanoparticles for drug delivery is still restricted by their limited stability when stored in an aqueous medium. Freeze drying is the standard method for long-term storage of colloidal nanoparticles; however the method needs to be elaborated for each formulation. Spray freeze drying (SFD) is proposed here as a promising alternative for lyophilizing colloidal nanoparticles. Different types of polymeric and lipid nanoparticles were prepared and characterized. Afterwards, samples were spray freeze dried by spraying into a column of cold air with a constant concentration of different cryoprotectants, and the frozen spherules were collected for further freeze drying. Similar samples w…
Immobilization and controlled release of prostaglandin E2 from poly-L-lactide-co-glycolide microspheres.
2009
Prostaglandin E(2) (PGE(2)) is an arachidonic acid metabolite involved in physiological homeostasis and numerous pathophysiological conditions. Furthermore, it has been demonstrated that prostaglandins have a stimulating effect not only on angiogenesis in situ and in vitro but also on chondrocyte proliferation in vitro. Thus, PGE(2) represents an interesting signaling molecule for various tissue engineering strategies. However, under physiological conditions, PGE(2) has a half-life time of only 10 min, which limits its use in biomedical applications. In the present study, we investigated if the incorporation of PGE(2) into biodegradable poly-L-lactide-co-glycolide microspheres results in a …
Microstructuring of phospholipid bilayers on gold surfaces by micromolding in capillaries
2005
Microstructuring of lipid bilayers on gold surfaces was achieved by micromolding in capillaries employing chemically modified polydimethylsiloxane (PDMS). Microfluidic networks of PDMS were prepared by micromolding and functionalized with thiol end-groups using 3-mercaptopropyltrimethoxysilane. The PDMS stamps were firmly attached to the gold substrate via quasi-covalent linkage providing a tight seal, a prerequisite for establishing individual addressable capillaries. Bilayers composed of POPC/POPG were subsequently prepared on microstructured self assembly monolayers of 11-amino-1-undecanethiol via strong electrostatic interactions. This way it is possible to generate individually address…
Core-shell PLA/Kef hybrid scaffolds for skin tissue engineering applications prepared by direct kefiran coating on PLA electrospun fibers optimized v…
2021
Abstract Over the recent years, there is a growing interest in electrospun hybrid scaffolds composed of synthetic and natural polymers that can support cell attachment and proliferation. In this work, the physical and biological properties of polylactic acid (PLA) electrospun mats coated with kefiran (Kef) were evaluated. Gravimetric, spectroscopic (FTIR-ATR) and morphological investigations via scanning electron microscopy confirmed the effective formation of a thin kefiran layer wrapped on the PLA fibers with an easy-tunable thickness. Air plasma pre-treatment carried out on PLA (P-PLA) affected both the morphology and the crystallinity of Kef coating as confirmed by differential scanning…
Carvacrol affects interfacial, structural and transfer properties of chitosan coatings applied onto polyethylene
2012
Different chitosan coating solutions were tested with the aim of investigating their adhesion and wettability onto polyethylene film to improve packaging performance and provide antimicrobial properties. Surface wetting kinetics was monitored by contact angle measurements. Addition of ethanol and carvacrol improved wettability and adhesion of the thin chitosan layer. Structure, water vapour, O2, CO2 and air permeabilities of self supported chitosan films and coated polyethylene were determined. The formation of a thin chitosan layer on polyethylene improved gas barrier properties decreasing the Permeability Coefficient for oxygen and carbon dioxide ( [Formula: see text] , [Formula: see text…
Structure and thermal properties of a chitosan coated polyethylene bilayer film
2012
The thermal and the structural properties of chitosan coated polyethylene (PE) films were studied. The coating process did not significantly influence the thermal stability and the PE surface structure and/or composition of the polyolefin. Dehydration temperature of chitosan films reflected the strength of water/acetic acid/chitosan chains interactions. Glycerol, used as a plasticizer, formed new hydrophilic centres in the film matrix. Moreover it was better integrated in the CSEGLY than in CSAGLY network. Besides, the addition of a plasticizer in the chitosan films decreased the film degradation temperature. There were two main steps for the PE chitosan coated films degradation. The first …
Routine preparation of air-dried negatively stained and unstained specimens on holey carbon support films: a review of applications.
2002
Several representative examples are given of the successful application of negative staining across the holes of holey carbon support films using 5% (w/v) ammonium molybdate solution containing trehalose. The inclusion of 0.1% (w/v) trehalose is considered to be most satisfactory, although good data have also been obtained in the presence of 0.01 and 1.0% (w/v) trehalose. The examples given fall into the following groups: protein molecules in the absence of polyethylene glycol (PEG), protein molecules in the presence of PEG (Mr 1000), lipoproteins, lipids and membranes, filaments and tubules, viruses in the absence of PEG, viruses in the presence of PEG, aqueous polymer solutions, and final…
Evaluation of the interaction and drug release from alpha,beta-polyaspartamide derivatives to a biomembrane model
2005
This article reports on a comparative study on the ability of various polymers, containing hydrophilic and/or hydrophobic groups, to interact with a biomembrane model using the differential scanning calorimetry (DSC) technique. Multilamellar vesicles of mixed dimyristoylphosphatidylcholine (DMPC) and dimyristoylphosphatidic acid (DMPA) were chosen as a model of cell membranes. The investigated samples were a water soluble polymer, the alpha,beta-poly(N-2-hydroxyethyl)-DL-aspartamide (PHEA) and its derivatives partially functionalized with polyethylene glycol (PEG2000) to obtain PHEA-PEG2000, with hexadecylamine (C16) to obtain PHEA-C16, and with both compounds to obtain PHEA-PEG2000-C16. Th…
Ultra-low density metallic foams synthesized by contact glow discharge electrolysis (CGDE) for laser experiments★
2018
International audience; The goal of this work is to realize metallic foams synthesized by contact glow discharge electrolysis with specific characteristics. In this paper, we show the results of our studies, consisting in investigating parameters that influence the foams characteristics. Thus, the morphology of metallic foams is examined through scanning electron microscopy (SEM) observations with the acid nature. Moreover, the evolution of the mass and the volume of metallic foams with two experimental parameters (overvoltage and gold concentration) is also investigated. The acid nature affects the foams microscopic structure highlighted by the SEM observations, but for now no valid explan…
Influence of Substrate Hydrophilicity on Structural Properties of Supported Lipid Systems on Graphene, Graphene Oxides, and Silica
2021
Pristine graphene, a range of graphene oxides, and silica substrates were used to investigate the effect of surface hydrophilicity on supported lipid bilayers by means of all-atom molecular dynamics simulations. Supported 1,2-dioleoyl-sn-glycero-3-phosphocholine lipid bilayers were found in close-contact conformations with hydrophilic substrates with as low as 5% oxidation level, while self-assembled monolayers occur on pure hydrophobic graphene only. Lipids and water at the surface undergo large redistribution to maintain the stability of the supported bilayers. Deposition of bicelles on increasingly hydrophilic substrates shows the continuous process of reshaping of the supported system a…