Search results for "Poly(methacrylic acid)"
showing 10 items of 29 documents
A NANOPARTICULATE DRUG-DELIVERY SYSTEM FOR RIVASTIGMINE: PHYSICO-CHEMICAL AND IN VITRO BIOLOGICAL CHARACTERIZATION
2007
The preparation and characterization of surface-PE Gylated polymeric nanoparticles are described. These systems were obtained by UV irradiation of PHM and PHM-PEG(2000) as an inverse microemulsion, using an aqueous solution of the PHM/PHM-PEG(2000) copolymer mixture as the internal phase and triacetin saturated with water as the external phase, and characterized by dimensional analysis, zeta-potential measurements and XPS. in vitro biological tests demonstrated their cell compatibility and their ability to escape from phagocytosis. Rivastigmine was encapsulated into the nanoparticle structure and drug-release profiles from loaded samples were investigated in PBS at pH = 7.4 and human plasma.
Hybrid methacrylate monolithic columns containing magnetic nanoparticles for capillary electrochromatography
2015
Abstract Vinylized iron oxide magnetic nanoparticles (VMNPs) were incorporated into polymethacrylate monolithic columns to develop novel stationary phases with enhanced separation performance. The VMNPs were dispersed in a polymerization mixture containing gycidyl methacrylate and ethylene glycol dimethacrylate as monomers, cyclohexanol and 1-dodecanol as porogens and azobisisobutyronitrile as initiator. The stability of the VMNPs in the polymerization mixture was investigated at several VMNP contents. Using short UV-polymerization times, polymeric beds with homogenously dispersed VMNPs were obtained. The novel stationary phases were characterized by scanning electron microscopy. The chroma…
Influence of photo-initiators in the preparation of methacrylate monoliths into poly(ethylene-co-tetrafluoroethylene) tubing for microbore HPLC.
2020
[EN] In this study, poly(butyl methacrylate-co-ethyleneglycol dimethacrylate) polymeric monoliths were in situ developed within 0.75 mm i.d. poly(ethylene-co-tetrafluoroethylene) (ETFE) tubing by UV polymerization via three different free-radical initiators fscce-azobisisobutyronitrile (AIBN), 2,2-dimethoxy-2-phenylacetophenone (DMPA) and 2-methyl-4'-(methylthio)-2-morpholinopropiophenone (MTMPP). The influence of the nature of each photo-initiator and irradiation time on the morphological features of the polymer was investigated by scanning electron microscopy, and the chromatographic properties of the resulting microbore columns were evaluated using alkyl benzenes as test substances. The …
Improvement of the butyl methacrylate-paraffin embedment.
1983
The excellent butyl methacrylate-paraffin method as an embedment for light microscopy has been technically improved. More uniform and reproducible polymerization has been obtained by using a vacuum oven to degas the polymerizing mixture and to replace the air with nitrogen at 650 Torr. The amount of benzoyl peroxide required must be determined for each batch of butyl methacrylate. A teflon lined, reusable metal mold and a method of one-step blocking of tissues in preparation for sectioning are also described.
A Deeper Insight into the Postpolymerization Modification of Polypenta Fluorophenyl Methacrylates to Poly(N -(2-Hydroxypropyl) Methacrylamide)
2014
This work provides a detailed insight into the synthesis of N-(2-hydroxypropyl)methacrylamide (HPMA) polymers employing the activated ester approach. In this approach, polypenta fluorophenyl methacrylate (PFPMA)-activated ester polymers are synthesized by the reversible addition-fragmentation chain transfer (RAFT) polymerization and transferred into HPMA-based systems by the use of 2-hydroxypropylamine. To prove quantitative conversion in the absence of side reactions, special attention is devoted to investigate different reaction conditions by different analytical methods ((1) H, (19) F, inverse-gated (13) C NMR, and zeta potential measurements). Furthermore the influence of common solvent…
Histidine-rich glycoprotein-induced vascular normalization improves EPR-mediated drug targeting to and into tumors
2018
Tumors are characterized by leaky blood vessels, and by an abnormal and heterogeneous vascular network. These pathophysiological characteristics contribute to the enhanced permeability and retention (EPR) effect, which is one of the key rationales for developing tumor-targeted drug delivery systems. Vessel abnormality and heterogeneity, however, which typically result from excessive pro-angiogenic signaling, can also hinder efficient drug delivery to and into tumors. Using histidine-rich glycoprotein (HRG) knockout and wild type mice, and HRG-overexpressing and normal t241 fibrosarcoma cells, we evaluated the effect of genetically induced and macrophage-mediated vascular normalization on th…
Reduction of Polymerization Shrinkage Stress and Marginal Microleakage Using Soft-Start Polymerization
2003
Purpose: This study evaluated the influence of a soft-start light-curing exposure on polymerization shrinkage stress and marginal integrity of adhesive restorations. Materials and Methods: Six resin-based composites (Pertac II, Tetric Ceram, Definite, Surefil, Solitaire, and Visio-Molar) were adhesively bonded to a cylindrical cavity (n = 9 per material/light) in a photoelastic material. Visible light-curing was applied using either the standard polymerization mode (800 mW/cm2 exposure duration 40 s) of the curing light (Elipar TriLight, 3M ESPE) or the exponential mode from the same device (ramp-curing: 150 mW/cm2 to 800 mW/cm2 within the first 15 s of a total curing time of 40 s). Polymer…
Rapid determination of sterols in vegetable oils by CEC using methacrylate ester-based monolithic columns
2008
A method for the determination of sterols in vegetable oils by CEC with UV-Vis detection, using methacrylate ester-based monolithic columns, has been developed. To prepare the columns, polymerization mixtures containing monomers of different hydrophobicities were tried. The influence of composition of polymerization mixture was optimized in terms of porogenic solvent, monomers/porogens and monomer/crosslinker ratios. The composition of the mobile phase was also studied. The optimum monolith was obtained with lauryl methacrylate monomer at 60:40% (wt:wt) lauryl methacrylate/ethylene dimethacrylate ratio and 60 wt% porogens with 20 wt% of 1,4-butanediol (12 wt% 1,4-butanediol in the polymeriz…
Freeze-dried eudragit-hyaluronan multicompartment liposomes to improve the intestinal bioavailability of curcumin.
2016
This work aimed at finding an innovative vesicle-type formulation able to improve the bioavailability of curcumin upon oral administration. To this purpose, phospholipid, Eudragit® S100 and hyaluronan sodium salt were combined to obtain eudragit-hyaluronan immobilized vesicles using an easy and environmentally-friendly method. For the first time, the two polymers were combined in a system intended for oral delivery, to enhance curcumin stability when facing the harsh environment of the gastrointestinal tract. Four different formulations were prepared, keeping constant the amount of the phospholipid and varying the eudragit-hyaluronan ratio. The freeze-drying of the samples, performed to inc…
Mechanical properties of provisional dental materials: A systematic review and meta-analysis
2018
Provisional restorations represent an important phase during the rehabilitation process, knowledge of the mechanical properties of the available materials allows us to predict their clinical performance. At present, there is no systematic review, which supports the clinicians' criteria, in the selection of a specific material over another for a particular clinical situation. The purpose of this systematic review and meta-analysis was to assess and compare the mechanical properties of dimethacrylates and monomethacrylates used in fabricating direct provisional restorations, in terms of flexural strength, fracture toughness and hardness. This review followed the PRISMA guidelines. The searche…