Search results for "Plastics"
showing 10 items of 2724 documents
Prenatal exposure to phthalates and its effects upon cognitive and motor functions : a systematic review
2021
Este artículo se encuentra disponible en la página web de la revista en la siguiente URL: https://www.sciencedirect.com/science/article/pii/S0300483X21003024?via%3Dihub Phthalates are chemicals widely used in packaging and consumer products, which have been shown to interfere with normal hormonal function and development in some human and animal studies. In recent decades, pregnant women’s exposure to phthalates has been shown to alter the cognitive outcomes of their babies, and some studies have found delays in motor development. Methods: electronic databases including PubMed/MEDLINE and Scopus were searched from their inception to March 2021, using the keywords "phthalate", "cognitive" an…
INULIN BASED HYDROGEL FOR ORAL DELIVERY OF FLUTAMIDE: PREPARATION, CHARACTERIZATION AND IN VIVO RELEASE STUDIES
2012
The ability of a hydrogel obtained by crosslinking INUDV and PEGBa to facilitate sustained release of flutamide is examined. The hydrogel is prepared in pH = 7.4 PBS and no toxic solvents or catalysts are used. It is recovered in microparticulate form and its size distribution is determined. Mucoadhesive properties are evaluated in vitro by reproducing gastrointestinal conditions. Flutamide is loaded into the hydrogel using a post-fabrication encapsulation procedure that allows a drug loading comparable to that of market tablets. Drug-loaded microparticles are orally administered to cross-bred dogs and the in vivo study demonstrates their ability to prolong the half-life of the principal ac…
Extended release and enhanced bioavailability of moxifloxacin conjugated with hydrophilic cellulose ethers.
2015
Macromolecular prodrugs (MPDs) of moxifloxacin were fabricated based on hydroxypropylcellulose (HPC) and hydroxyethylcellulose (HEC). UV/Vis spectrophotometry was employed to determine covalently loaded drug content (DC) of each conjugate. The degree of substitution (DS) of moxifloxacin attained ranged from 0.27 to 0.38 (HPC) and 0.19 to 0.26 (HEC) per anhydroglucose unit (AGU), respectively. Transmission electron microscopic analyses showed that HPC-moxifloxacin conjugates self-assembled into nanowires of ∼ 30 nm diameters while HEC-moxifloxacin conjugates self-assembled into nanoparticles of 150-350 nm. In vitro drug release studies revealed that 15 and 49% moxifloxacin release occurred f…
Celebrating 100 years of “polymer science”: Hermann Staudinger's 1920 manifesto
2020
The first translation into English of Hermann Staudinger's seminal 1920 paper ‘On polymerisation’, to mark its 100 year anniversary.
Stepwise Lateral Extension of Phenyl‐Substituted Linear Polyphenylenes
2019
Polyphenylenes (PPs) are unique polymers showing high mechanical strength and chemical stability, and having potential applications, for example, in proton transfer and gas‐separation membranes. Moreover, phenyl‐substituted linear PPs can serve as precursors for bottom‐up syntheses of graphene nanoribbons (GNRs), a new class of nanoscale carbon materials that appear promising for nanoelectronics. Notably, lateral extensions of linear PPs with appropriate “branched” phenyl substituents, that is, avoiding spatial overlap of benzene rings in their projections into a plane, can lead to wider GNRs with modulated electronic and optical properties. GNRs with widths up to ≈2 nm are obtained, but sy…
Coagulation bath composition and desiccation environment as tuning parameters to prepare skinless membranes via diffusion induced phase separation
2015
Diffusion Induced Phase Separation (DIPS) is a currently used technique to produce porous membranes for a large variety of applications. A strong limitation is represented by the occurrence of a dense skin, which is formed during the process, highly reducing the membrane permeability. To overcome this issue, two modifications of the standard DIPS protocol were investigated: the use of coagulation baths composed by a solvent/nonsolvent mixture and the desiccation in a controlled environment, by modulating the partial pressure of nonsolvent vapor. An appropriate choice of coagulation bath composition, together with an appropriate desiccation protocol (i.e., the use of a nonsolvent vapor), wil…
Temperature-induced self-assembly of degalactosylated xyloglucan at low concentration
2015
Xyloglucan is a natural polysaccharide having a cellulose-like backbone and hydroxyl groups-rich side-chains. In its native form the polymer is water-soluble and forms gel only in presence of selected co-solutes. When a given fraction of galactosyl residues are removed by enzymatic reaction, the polymer acquires the ability to form a gel in aqueous solution at physiological temperatures, a property of great interest for biomedical/pharmaceutical applications. This work presents data on the effect of a temperature increase on degalactosylated xyloglucan dispersed in water at concentration low enough not to run into macroscopic gelation. Results obtained over a wide interval of length scales …
Pluronic nanoparticles as anti-oxidant carriers for polymers
2016
Abstract The immobilization of anti-oxidant stabilizers for polymers, particularly naturally occurring systems, can be considered a valuable route for preventing their migration, volatilization, thermo-degradation and decomposition at typical high processing temperatures, as well as for enhance their solubility in polymers. In this work, an innovative approach for the immobilization of naturally occurring stabilizer, through the encapsulation in copolymer nanoparticles, is proposed. Pluronic nanoparticles (PNPs), based on PEO-PPO-PEO, (PEO: poly (ethylene oxide); PPO: poly(propylene oxide)), without and with quercetin, Q, have been successfully formulated and the critical micellar condition…
Polymeric micelles as a new generation of anti-oxidant carriers
2017
A promising strategy to immobilize a natural stabilizer in polymeric films is presented. Par-Ticularly, nevadensin (N, a natural basil flavonoid) molecules have been encapsulated in Pluronic F-127 micelles [F127, a triblock copolymer poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide)] and the obtained nanoparticles have been introduced in poly(ethylene glycol), PEG [otherwise known as poly(ethylene oxide), PEO]. In order to verify the effectiveness of the micelles as anti-oxidant carriers, PEG-based films have been subjected to artificial weathering. The encapsulation of anti-oxidant molecules allows the enhancement of N solubility in PEG, leading to advanced materials with enh…
Thermo-oxidative stabilization of poly(lactic acid)-based nanocomposites through the incorporation of clay with in-built antioxidant activity
2017
In this work, an innovative approach to overcome the issue of the poor thermo-oxidative stability of polymer/clay nanocomposites is proposed. Specifically, biodegradable poly(lactic acid) (PLA)-based nanocomposites, containing organo-modified clay with in-built antioxidant activity, were prepared. Through a two-step chemical protocol, a hindered phenol antioxidant was chemically linked to the ammonium quaternary salt which was then intercalated between the clay platelets [(AO)OM-Mt]. The nanocomposites were characterized and their thermo-oxidative stability during melt processing and under long-term thermal test conditions was investigated. PLA nanocomposites containing the (AO)OM-Mt showed…