Search results for "Polyester"
showing 10 items of 221 documents
Contribution of outgrowth endothelial cells from human peripheral blood on in vivo vascularization of bone tissue engineered constructs based on star…
2009
In the present study we assessed the potential of human outgrowth endothelial cells (OEC), a subpopulation within endothelial progenitor cell cultures, to support the vascularization of a complex tissue engineered construct for bone. OEC cultured on starch polycaprolactone fiber meshes (SPCL) in monoculture retained their endothelial functionality and responded to angiogenic stimulation by VEGF (vascular endothelial growth factor) in fibrin gel-assays in vitro. Co-culture of OEC with human primary osteoblasts (pOB) on SPCL, induced an angiogenic activation of OEC towards microvessel-like structures achieved without additional supplementation with angiogenic growth factors. Effects of co-cul…
Reactive blending of a functionalized polyethylene with a semiflexible liquid crystalline copolyester
1996
Reactive blends (50/50 w/w) of a low molar mass polyethylene containing free carboxylic groups (PEox) and a semiflexible liquid crystalline polyester (SBH 1 : 1 : 2, by Eniricerche) have been prepared at 240 degrees C in a Brabender mixer, in the presence of Ti(OBu)(4) catalyst, for different mixing times (15, 60, and 120 min). In order to prove the formation of a PE-g-SBH copolymer, the blends have been fractionated by successive extractions with boiling toluene and xylene. The soluble fractions and the residues have been analyzed by Fourier transform infrared (FTIR) spectroscopy, thermogravimetry (TG and DTG), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM)…
Antibacterial suture vs silk for the surgical removal of impacted lower third molars. A randomized clinical study.
2015
Background The aim of this study was to evaluate the clinical and microbiological impact of an antibacterial suture (Monocryl® Plus) in the surgical removal of I3M. Material and Methods A “split-mouth”, prospective pilot clinical study was designed involving 20 patients programmed for the surgical removal of I3M. Each side was randomly sutured with Monocryl® Plus or silk suture and removed for microbiological study 72 hours and 7 days after surgery. Presence of SSI, wound bleeding and the degree of discomfort associated with each type of suture material (scored by means of a visual analog scale) were evaluated. The level of contamination of each material was observed under the scanning elec…
1-n-Butyl-3-methylimidazolium-2-carboxylate: a versatile precatalyst for the ring-opening polymerization of ε-caprolactone and rac-lactide under solv…
2013
The ring-opening polymerization of ε-caprolactone (ε-CL) and rac-lactide (rac-LA) under solvent-free conditions and using 1-n-butyl-3-methylimidazolium-2-carboxylate (BMIM-2-CO2) as precatalyst is described. Linear and star-branched polyesters were synthesized by successive use of benzyl alcohol, ethylene glycol, glycerol and pentaerythritol as initiator alcohols, and the products were fully characterized by 1H and 13C{1H} NMR spectroscopy, gel permeation chromatography (GPC), and differential scanning calorimetry (DSC). BMIM-2-CO2 acts as an N-heterocyclic carbene precursor, resulting from in situ decarboxylation, either by heating under vacuo (method A) or by addition of NaBPh4 (method B)…
Galactosylated polymeric carriers for liver targeting of sorafenib
2014
In this paper, we describe the preparation of liver-targeted polymeric micelles potentially able to carry sorafenib to hepatocytes for treatment of hepatocarcinoma (HCC), exploiting the presence of carbohydrate receptors, ASGPR. These micelles were prepared starting from a galactosylated polylactide-polyaminoacid conjugate. This latter was obtained by chemical reaction of α,β-poly(N-2-hydroxyethyl) (2-aminoethylcarbamate)-d,l-aspartamide (PHEA-EDA) with polylactic acid (PLA), and subsequent reaction with lactose, leading to PHEA-EDA-PLA-GAL copolymer. Liver-targeted sorafenib-loaded micelles were obtained in aqueous media at low PHEA-EDA-PLA-GAL copolymer concentration value with nanometer …
Resource or waste? A perspective of plastics degradation in soil with a focus on end-of-life options.
2018
‘Capable-of-being-shaped’ synthetic compounds are prevailing today over horn, bone, leather, wood, stone, metal, glass, or ceramic in products that were previously left to natural materials. Plastic is, in fact, economical, simple, adaptable, and waterproof. Also, it is durable and resilient to natural degradation (although microbial species capable of degrading plastics do exist). In becoming a waste, plastic accumulation adversely affects ecosystems. The majority of plastic debris pollutes waters, accumulating in oceans. And, the behaviour and the quantity of plastic, which has become waste, are rather well documented in the water, in fact. This review collects existing information on pla…
Oxazoline functionalization of polyethylenes and their blends with polyamides and polyesters
2001
The compatibilization of blends of polyamide-6 (PA6) with linear low density polyethylene (LLDPE) and of poly(ethylene terephthalate) (PET) with high density polyethylene (HDPE), by functionalization of the polyethylenes with oxazoline groups was investigated. Chemical modification of LLDPE and HDPE was carried out by melt free radical grafting with ricinoloxazoline maleinate. Blends preparation was made either with a two-steps procedure comprising functionalization and blending, and in a single step in which the chemical modification of polyethylene with the oxazoline monomer was realized in situ, during blending. The characterization of the products was carried out by FTIR spectroscopy an…
P(HPMA)-block-P(LA) copolymers in paclitaxel formulations: Polylactide stereochemistry controls micellization, cellular uptake kinetics, intracellula…
2012
In order to explore the influence of polymer microstructure and stereochemistry in biological settings, the synthesis, micellization, cellular fate and the use in paclitaxel formulations of poly(N-(2-hydroxypropyl)-methacrylamide)-block-poly(L-lactide) (P(HPMA)-block-P(LLA)) and poly(N-(2-hydroxypropyl)-methacrylamide)-block-poly(DL-lactide) block copolymers (P(HPMA)-block-P(DLLA)) were studied. To this end, P(HPMA)-block-P(lactide) block copolymers and their fluorescently labeled analogues were synthesized. The polymers exhibited molecular weights M-n around 20,000 g/mol with dispersities (D=M-w/M-n) below 1.3. In addition, the solution conformation of this new type of partially degradable…
Adhesion prophylaxis using a copolymer with rationally designed material properties.
2008
Physical barriers are the only licensed adjuncts for adhesion prophylaxis in the United States and Europe. Here, we investigate D,L-polylactide-epsilon-caprolactonetrimethylenecarbonate (PCT copolymer), which is a rationally designed biomaterial, as an adhesion barrier.PCT copolymer membranes were produced by polymerization of the monomers, dissolution in organic solvents, and subsequently processing them by means of modified phase inversion and freeze drying. In vitro cytotoxicity was assayed by fibroblast culture. In vivo adhesion prophylaxis was studied in a rat model that involved standardized traumatization by electrocautery and suturing. The quantity and quality of the resulting adhes…
Margination of Fluorescent Polylactic Acid-Polyaspartamide based Nanoparticles in Microcapillaries In Vitro: the Effect of Hematocrit and Pressure.
2017
The last decade has seen the emergence of vascular-targeted drug delivery systems as a promising approach for the treatment of many diseases, such as cardiovascular diseases and cancer. In this field, one of the major challenges is carrier margination propensity (i.e., particle migration from blood flow to vessel walls); indeed, binding of these particles to targeted cells and tissues is only possible if there is direct carrier–wall interaction. Here, a microfluidic system mimicking the hydrodynamic conditions of human microcirculation in vitro is used to investigate the effect of red blood cells (RBCs) on a carrier margination in relation to RBC concentration (hematocrit) and pressure drop…