Search results for " Copolymer"

Polyhydroxyethylaspartamide-based micelles for ocular drug delivery

2009

In this paper three copolymers of polyhydroxyethylaspartamide (PHEA), bearing in the side chains polyethylene glycol (PEG) and/or hexadecylamine (C(16)) (PHEA-PEG, PHEA-PEG-C(16) and PHEA-C(16) respectively) have been studied as potential colloidal drug carriers for ocular drug delivery. The physical characterization of all three PHEA derivatives, using the Langmuir trough (LT) and micellar affinity capillary electrophoresis (MACE) techniques allowed to assume that whereas alone PHEA backbone is an inert polymer with respect to the interactions with lipid membranes and drug complexation, when PHEA chains are grafted with long alkyl chains like C(16) or in combination C(16) chains and hydrop…

Local Delivery of Nimodipine by Prolonged-Release Microparticles—Feasibility, Effectiveness and Dose-Finding in Experimental Subarachnoid Hemorrhage

2012

Background and purposeTo investigate the effect of locally applied nimodipine prolonged-release microparticles on angiographic vasospasm and secondary brain injury after experimental subarachnoid hemorrhage (SAH).Methods70 male Wistar rats were categorized into three groups: 1) sham operated animals (control), 2) animals with SAH only (control) and the 3) treatment group. SAH was induced using the double hemorrhage model. The treatment group received different concentrations (20%, 30% or 40%) of nimodipine microparticles. Angiographic vasospasm was assessed 5 days later using digital subtraction angiography (DSA). Histological analysis of frozen sections was performed using H&E-staining as …

?Reliability of new poly (lactic-co-glycolic acid) membranes treated with oxygen plasma plus silicon dioxide layers for pre-prosthetic guided bone re…

2017

Background: The use of cold plasmas may improve the surface roughness of poly(lactic-co-glycolic) acid (PLGA) membranes, which may stimulate the adhesion of osteogenic mediators and cells, thus accelerating the biodegradation of the barriers. Moreover, the incorporation of metallic-oxide particles to the surface of these membranes may enhance their osteoinductive capacity. Therefore, the aim of this paper was to evaluate the reliability of a new PLGA membrane after being treated with oxygen plasma (PO) plus silicon dioxide (SiO) layers for guided bone regeneration (GBR) processes. Material and Methods: Circumferential bone defects (diameter: 11 mm; depth: 3 mm) were created on the top of ei…

Ultrasonographic mound height as predictor of vesicoureteral reflux resolution after endoscopic treatment in children

2016

Purpose: Endoscopic dextranomer/hyaluronic acid copolymer (Dx/HA) injection is a safe and efficacious treatment option for vesicoureteral reflux (VUR) in children. Endoscopic appearance, hydrodistention and amount of injected Dx/HA have been demonstrated not to be reliable predictors of outcome. Aim of this study was to evaluate Dx/HA mounds on ultrasound scans (US) and find out any eventual correlation with reflux resolution. Methods: We selected patients treated with endoscopic injection for moderate to high VUR, renal scaring or repeated infections under antibiotic prophylaxis. Success was defined by absence of VUR at control 3. months after surgery; at 3. months we also measured mound h…

Inclusion complexes of triblock L35 copolymer and hydroxyl propyl cyclodextrins: a physico-chemical study

2022

In this work, we studied the formation of supramolecular inclusion complexes (pseudopolyrotaxanes) generated by the interactions between L35 Pluronic (PEO-PPO-PEO triblock copolymer) and hydroxyl propyl-modified cyclodextrins (HP-alpha-CD and HP-beta-CD). The structural characteristics of the L35/CD composites were investigated by X-ray diffraction spectroscopy, which highlighted the effective inclusion of the copolymer. The thermodynamic properties of the pseudopolyrotaxanes were determined through density and speed of sound experiments conducted on aqueous mixtures with various L35/CD compositions, while turbidimetric analyses allowed the investigation of the kinetics of the threading pro…

NANOPARTICLES BASED ON NOVEL AMPHIPHILIC POLYASPARTAMIDE COPOLYMERS

2010

In this article, the synthesis of two amphiphilic polyaspartamide copolymers, useful to obtain polymeric nanoparticles without using surfactants or stabilizing agents, is described. These copolymers were obtained starting from α,β-poly-(N-2-hydroxyethyl)-dl-aspartamide (PHEA) by following a novel synthetic strategy. In particular, PHEA and its pegylated derivative (PHEA-PEG2000) were functionalized with poly(lactic acid) (PLA) through 1,1′-carbonyldiimidazole (CDI) activation to obtain PHEA–PLA and PHEA-PEG2000–PLA graft copolymers, respectively. These copolymers were properly purified and characterized by 1H-NMR, FT-IR, and Size Exclusion Chromatography (SEC) analyses, which confirmed that…

Porphyrin Antenna-Enriched BODIPY–Thiophene Copolymer for Efficient Solar Cells

2018

International audience; Low bandgap A−π–D copolymer, P(BdP-DEHT), consisting of alternating BOronDIPYrromethene (BODIPY) and thiophene units bridged by ethynyl linkers, and its porphyrin-enriched analogue, P(BdP/Por-DEHT), were prepared, and their optical and electrochemical properties were studied. P(BdP-DEHT) exhibits strong absorption in the 500–800 nm range with an optical bandgap of 1.74 eV. On the basis of cyclic voltammetry, the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels are evaluated to be −5.40 and −3.66 eV, respectively. After the anchoring of zinc(II) porphyrin on the BODIPY unit, P(BdP/Por-DEHT) displays broadened absor…

Random Structural Modification of a Low-Band-Gap BODIPY-Based Polymer

2017

International audience; A BODIPY thiophene polymer modified by extending conjugation of the BODIPY chromophore is reported. This modification induces tunability of energy levels and therefore absorption wavelengths in order to target lower energies.

Biocompatible micelles based on squalene portions linked to pegylated polyaspartamide as potential colloidal drug carriers

2011

Hierarchical Self-Assembly of Halogen-Bonded Block Copolymer Complexes into Upright Cylindrical Domains

2017

Summary Self-assembly of block copolymers into well-defined, ordered arrangements of chemically distinct domains is a reliable strategy for preparing tailored nanostructures. Microphase separation results from the system, minimizing repulsive interactions between dissimilar blocks and maximizing attractive interactions between similar blocks. Supramolecular methods have also achieved this separation by introducing small-molecule additives binding specifically to one block by noncovalent interactions. Here, we use halogen bonding as a supramolecular tool that directs the hierarchical self-assembly of low-molecular-weight perfluorinated molecules and diblock copolymers. Microphase separation …