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PubMed1993

Protein adsorption to poly(ether urethane ureas) modified with acrylate and methacrylate polymer and copolymer additives.

To understand better blood interactions with poly(ether urethane urea) (PEUU) materials, a radioimmunoassay and whole or diluted human plasma were used to characterize the presence of fibrinogen, immunoglobulin G, factor VIII/von Willebrand factor, Hageman factor (factor XII), and albumin on a PEUU formulation and on PEUU formulations modified with the amphiphilic additive Methacrol 2138F (co[diisopropylaminoethyl methacrylate (DIPAM)/decyl methacrylate] [3/1]), or with hydrophobic acrylate or methacrylate polymer or copolymer additives. The protein adsorption assay showed that PEUU films loaded or coated with Methacrol 2138F (Methacrol) or homopoly-DIPAM (h-DIPAM) adsorbed significantly lower amounts of the studied proteins than did either the base PEUU formulations or the PEUUs loaded with the more hydrophobic acrylate or methacrylate polymer additives. Experiments with Methacrol-loaded PEUUs, where the loading of Methacrol was varied from 0.25 wt% to 20.0 wt%, showed that the adsorption of each of the characterized proteins did not vary significantly throughout the Methacrol loading range, and that all Methacrol-loaded PEUU formulations adsorbed significantly lower amounts of the studied proteins than did the unloaded PEUU. Phase separation within the additive loaded PEUUs was characterized by scanning electron microscopy (SEM). The solubility parameters of the additives, as well as of the base PEUU, were calculated and used to interpret differences in phase separation of the additive modified PEUUs. The analysis showed that additives of lower solubility parameter phase-separated into fewer large microdroplets within the PEUU matrix. SEM analysis also showed that additive microdroplets were not present on the air side surface of loaded PEUUs. To explain the differences in protein adsorption to the air side of additive loaded PEUUs when compared to the base PEUU, it was assumed that the additives near this region of the solvent swollen PEUU matrix may have migrated to, at, or near the PEUU-air interface during film formation, creating an additive enriched PEUU surface region. Once at this surface region, it was suggested that dynamic surface reorientation in response to an aqueous medium ensured that the additives were able significantly to influence protein adsorption behavior only if they interacted with aqueous media more favorably than the PEUU.

Acrylates↗
PubMed1995

Dynamic creep behavior of acrylic bone cement.

Recent studies concerning the fixation of cemented total hip arthroplasty (THA) have led to new hypotheses about the dynamic, long-term failure mechanisms leading to prosthetic loosening. As a result, the long-term mechanical behavior of acrylic bone cement has gained more interest since little is known about these properties. In this study, the dynamic, compressive creep deformation of acrylic bone cement was examined. An amount of creep was found, with creep strains exceeding the elastic strain during 14 x 10(6) loading cycles. There was a linear relationship between the logarithmic values of the number of loading cycles and the creep strain. The effect of stress level on the amount of creep was different from that in results of static experiments reported in the literature. Comparing the results with tensile creep experiments revealed that bone cement under a tensile load creeps much quicker than under a compressive one. Young's modulus was significantly higher when the material was loaded at higher strain rates. The bone cement became stiffer with an increasing number of loading cycles. The creep behavior of bone cement is important for the long-term behavior of cemented THA. It enables subsidence of the stem and attenuation of stress peaks in the cement mantle.

Acrylates↗
PubMed2004

Chemoenzymatic synthesis of sugar-containing biocompatible hydrogels: crosslinked poly(beta-methylglucoside acrylate) and poly(beta-methylglucoside methacrylate).

Sugar-containing biocompatible hydrogels were synthesized chemoenzymatically by the following two steps: 1. lipase-catalyzed esterification of beta-methylglucoside with acrylic acid/methacrylic acid/vinyl acrylate/vinyl methacrylate in solvent as well as solvent-free process for the formation of sugar-containing monomers; and 2. polymerization process by free-radical polymerization with and without a crosslinker, ethylene glycol dimethacrylate (EGDMA). The solvent-free process resulted in an initial reaction rate approximately 1.5-2 times faster than that of the solvent process along with a complete consumption of beta-methylglucoside during the alcoholysis. The presence of pendant vinyl groups in beta-methylglucoside acrylate (MGAA) and beta-methylglucoside methacrylate (MGMAA) was confirmed by (1)H/(13)C NMR analysis, whereas the successful polymerization with the consumption of the vinyl groups was confirmed by Fourier transform infrared spectroscopy and (13)C NMR spectra. The surfaces of both poly(MGAA) and poly(MGMAA) were analyzed using scanning electron microscopy. The increased contents of EGDMA resulted in a higher tensile strength as well as a reduced swelling ratio of poly(MGAA) and poly(MGMAA). The swelling exponents were within the range of 0.53 and 0.98. In vitro cytotoxicity tests by MTT assay exhibited >90% cell viability in the poly(MGAA) and poly(MGMAA) without EGDMA, whereas a significantly decreased cell viability was observed for those with EGDMA.

Acrylates↗
PubMed2005

Synthetic MMP-13 degradable ECMs based on poly(N-isopropylacrylamide-co-acrylic acid) semi-interpenetrating polymer networks. I. Degradation and cell migration.

Thermoresponsive and injectable semi-interpenetrating polymer networks (sIPNs) containing a biospecific cell-adhesive signal and proteolytically degradable domains were developed as a synthetic equivalent of the extracellular matrix (ECM). The sIPNs synthesized define a modular hydrogel ECM where different properties of the matrix can be manipulated independently, thus creating a system where parametric analysis of the effect of hydrogel properties on cell proliferation and differentiation is possible. sIPNs composed of poly(N-isopropylacrylamide-co-acrylic acid) [p(NIPAAm-co-AAc)] and RGD-grafted poly(acrylic acid) linear chains [p(AAc)-g-RGD] were synthesized with peptide crosslinkers containing a matrix metalloproteinase-13 (MMP-13, collagenase-3) degradable domain. The lower critical solution temperature (LCST) of peptide-crosslinked p(NIPAAm-co-AAc) sIPNs was not influenced by the addition of either linear p(AAc) or peptide-modified p(AAc) chains ( approximately 34 degrees C) in PBS. Degradation of peptide-crosslinked hydrogels and sIPNs was enzyme specific and concentration dependent. Exposure of rat calvarial osteoblast (RCO) culture to the degradation products from the peptide-crosslinked hydrogels did not significantly affect cell viability. Migration of RCOs into the sIPNs was dependent upon the presence of both a cell-adhesive RGD peptide (Ac-CGGNGEPRGDTYRAY-NH2) and proteolytically-degradable crosslinks; however, there was greater dependence on the latter. The sIPNs synthesized are versatile materials for assessing cell fate in synthetic ECM constructs in vitro and tissue regeneration in vivo.

Acrylamides↗
PubMed2006

Novel alginate-acrylic polymers as a platform for drug delivery.

The aim of the present work was to develop a family of novel materials based on a combination of sodium alginate and acrylic polymers and to evaluate their potential in drug delivery applications. In the presence of sodium alginate, acrylic chains with acidic as well as basic moieties were polymerized to create an interpolymer complex based on electrostatic interactions that are able to modulate the release rate of low molecular weight drugs. The synthesized materials were used to prepare hydrophilic matrices for drug delivery and tested for their adhesion properties to glass, used as a model substrate for mucoadhesion.

Acrylates↗
PubMed2006

Influence of polymerization method, curing process, and length of time of storage in water on the residual methyl methacrylate content in dental acrylic resins.

This study compared the influence of different polymerization methods (heat, auto-, and microwave energy), different curing processes (in the case of heat- and autopolymerized specimens), and length of storage of the polymerized specimens in distilled water at 37 degrees C on the residual methyl methacrylate (MMA) content in dental acrylic resin specimens. Residual MMA of 120 resin specimens were measured using high-performance liquid chromatography. For the heat-polymerized resins, the lowest residual MMA content was obtained when they were given a long-term terminal boil and then stored in the distilled water for at least 1 day. For the autopolymerized resins, the lowest residual MMA content was obtained when they were additionally cured in water at 60 degrees C and then stored in the distilled water at least 1 day. For the microwave-polymerized resins, the lowest residual MMA content was obtained when they were stored in the distilled water at least 1 month. The lowest overall residual MMA content was obtained from heat-polymerized specimens that were given a long-term terminal boil cure and then stored in the distilled water at least 1 day. Different polymerization methods and curing processes have different effects on residual MMA content. It is thus shown that storing a dental acrylic resin specimen in distilled water at 37 degrees C is a simple but effective method of reducing its residual MMA content.

Acrylic Resins↗
PubMed1979

Controlled drug dissolution by radiation-induced polymerization in the presence of dimethylaminoethyl methacrylate-methyl methacrylate copolymer or methacrylic acid-methyl acrylate copolymer.

Polymer-containing tablet preparation was studied using radiation-induced polymerization of glass-forming monomers at low temperatures in the presence of dimethylaminoethyl methacrylate-methyl methacrylate copolymer or methyl acrylate-methacrylic acid copolymer. Drug dissolution from tablets was in the pH 3.0-8.0 range. A copolymer contained in the tablets dissolved in the dissolution medium at a specific pH. Drug dissolution from tablets took place rapidly at pH greater than 6.0 in the presence of methyl acrylate-methacrylic acid copolymer and at pH less than 5.0 in the presence of dimethylaminoethyl methacrylate-methyl methacrylate copolymer. The polymers had fibrous or capillary pore structures in contrast to the spherical pore structures formed in the presence of polyethylene glycol 600.

Acrylic Resins↗
PubMed1989

Preparation of controlled-release microspheres of ibuprofen with acrylic polymers by a novel quasi-emulsion solvent diffusion method.

A novel quasi-emulsion solvent diffusion method to prepare the controlled-release microspheres of ibuprofen with acrylic polymers has been developed. An ethanol solution of ibuprofen and acrylic resin was poured into aqueous medium with stirring. The finely dispersed ethanolic droplet-like coacervates formed in aqueous medium were gradually solidified and transformed into microspheres during agitation. The size of microspheres was determined by the concentrations of drug and polymer and the agitation speed of the system. The flowability, the packability, and the compressibility of the resultant microspheres were much improved compared with the raw crystals of the drug. The drug release rate from the microspheres could be controlled by the type and the concentration of polymer formulated. A unique principle of the present method and the resultant microspheres, having a matrix- or sponge-like texture, can provide characteristic advantages compared with a conventional reservoir-type device drug, like a microcapsule.

Acrylates↗
PubMed2004

Acrylonitrile-acrylic acid copolymer membrane imprinted with uric acid for clinical uses.

The preparation of new polymeric membranes using molecular imprinting technology for application in blood filtration devices is described. Membranes, based on an acrylic acid-acrylonitrile copolymer, produced through phase inversion, were modified by introducing specific binding sites for uric acid into their structure. The materials prepared are intended for use to selectively remove uric acid from the blood in the case of increased serum uric acid values associated with different pathologies. The interactions at a molecular level between the membrane forming copolymer and the template were investigated by means of calorimetry, infrared spectroscopy and morphological analysis. The presence of interactions between the template and the copolymer, and a good thermal stability of the imprinted membranes were observed. In addition, the results of rebinding tests on the imprinted membranes indicated a good capacity of molecular recognition for the template and satisfactory selectivity properties towards compounds of similar structure such as theophylline. Membrane permeability values suggest their application as (ultra) haemofiltration devices. Poly(acrylonitrile-co-acrylic acid) membrane.

Acrylates↗
PubMed2004

Synthesis of nanosized chitosan-poly(acrylic acid) particles by a dropping method.

Deoxyribonucleic acid (DNA) vaccines are being investigated extensively because of their excellent potential over conventional protein ones. A suitable DNA carrier, consisting of uniformly dispersed chitosan-poly(acrylic acid) particles with an average size of 30 nm, was successfully synthesized by a dropping method with a ratio of chitosan solution to poly(acrylic acid) solution of 1:1 and was incubated in a buffer solution with a pH value of 3.0. The particle size increased from 35.76 to 45.90 nm when the pH value of the buffer solution was increased from 3.0 to 7.4. After freeze-drying, the non-incubated mixed solution showed a membranous morphology. A powdered product was formed from the mixed solution as incubated in buffer solution with pH values of 3.0 and 5.3. However, when the mixed solution was incubated in a buffer solution of pH 7.4, a mixture of membrane and powder was obtained.

Acrylic Resins↗
PubMed2005

pH effects on the complexation, miscibility and radiation-induced crosslinking in poly(acrylic acid)-poly(vinyl alcohol) blends.

The effect of pH on the complexation of poly(acrylic acid) with poly(vinyl alcohol) in aqueous solution, the miscibility of these polymers in the solid state and the possibility for crosslinking the blends using gamma radiation has been studied. It is demonstrated that the complexation ability of poly(vinyl alcohol) with respect to poly(acrylic acid) is relatively low in comparison with some other synthetic non-ionic polymers. The precipitation of interpolymer complexes was observed below the critical pH of complexation (pH(crit1)), which characterizes the transition between a compact hydrophobic polycomplex and an extended hydrophilic interpolymer associate. Films prepared by casting from aqueous solutions at different pH values exhibited a transition from miscibility to immiscibility at a certain critical pH, pH(crit2), above which hydrogen bonding is prevented. It is shown here that gamma radiation crosslinking of solid blends is efficient and only results in the formation of hydrogel films for blends prepared between pH(crit1) and pH(crit2). The yield of the gel fraction and the swelling properties of the films depended on the absorbed radiation dose and the polymer ratio. [Diagram: see text] SEM image of an equimolar PAA-PVA blend cast from a pH 4.6 solution.

Acrylic Resins↗
PubMedDate not supplied

Demonstration of the glycocalyces associated with three oral gram-negative bacterial species using a modern acrylic resin technique.

The complex highly hydrated chemical composition of the bacterial glycocalyx renders it difficult to preserve and visualize at the ultrastructural level. Polyanionic stains such as ruthenium red help to maintain some structural integrity, and other more modern approaches include antibody stabilization, lectins, and the addition of lysine to the primary fixative. It has been suggested that the glycocalyx of certain disease-associated organisms may play a role in the pathogenesis of some microbially based diseases such as periodontitis. New, more adequate, modern methodologies are therefore required for the further study of this structure. In the present study a cold dehydration process in conjunction with LR white acrylic resin has been employed to study the glycocalyces of three oral gram-negative bacterial species reported to be periodontopathogens. When compared with organisms processed conventionally and with ruthenium red, the organisms processed by the cold dehydration and LR white method demonstrated a fibrous matrix that was not seen in the other specimens. These results indicate that a combination of reduced dehydration temperature and cold acrylic resin embedding provides the best methodology for the visualization of the fine structure of the bacterial glycocalyx. This approach may be particularly useful in the study of organisms within specific disease-associated environments such as the periodontal pocket.

Acrylic Resins↗
PubMed1998

Acrylic acid induces the glutathione-independent mitochondrial permeability transition in vitro.

Acrylic acid (AA) is used widely in the synthesis of esters essential in the production of paints, adhesives, plastics, and coatings. The minimal systemic toxicity of AA is attributed to its rapid oxidation to acetyl-CoA and CO2 via the vitamin B12-independent beta-oxidation pathway. This oxidation is localized to the mitochondria and preliminary evidence suggests a possible inhibition of mitochondrial metabolism by acrylic acid. The purpose of this investigation was to evaluate whether AA interferes with mitochondrial bioenergetics in vitro. Incubation of isolated rat liver mitochondrial with AA resulted in a dose-dependent induction of the mitochondrial permeability transition (MPT). This was evidenced by an increased sensitivity to calcium-induced stimulation of state 4 oxygen consumption, depolarization of membrane potential, and swelling, all of which were prevented by preincubating the mitochondrial with cyclosporine A, a potent and specific inhibitor of the mitochondrial permeability transition pore. Both N-ethylmaleimide (NEM) and dithiothreitol (DTT) showed only partial protection against induction of the MPT by AA. Associated with the induction of the MPT by AA was the loss of mitochondrial glutathione (GSH), which was due to efflux from the matrix rather than oxidation to GSSG. Cyclosporine A, by inhibiting the permeability transition, prevented the AA-induced loss of mitochondrial GSH. In conclusion, AA increases the sensitivity of isolated mitochondria in vitro to the calcium-dependent induction of the MPT. Although the molecular mechanism has yet to be defined, it does not appear to be related to the oxidation of critical thiols.

Acrylates↗
PubMed1988

Posterior acrylic surgical fixation of odontoid fractures.

Fourteen cases of odontoid fractures had, as primary treatment, a posterior surgical fixation (C1 + C2 + C3 and occiput in some cases) by means of acrylate and stainless steel wires, without waiting for the unpredictable final results of external systems of stabilization. The youngest patient was 20 years old, the oldest 84 years old. No immediate or late neurological complications occurred (follow-up: one year to ten years). All the patients were mobilized early without external fixation. Union of the dens took place in eleven cases, and good stabilization in the remainder. Thirteen patients recovered, one improved. Posterior acrylic fixation is the treatment of choice in cases of odontoid fracture, particularly in elderly patients in whom a solid union rarely is obtained.

Acrylates↗
PubMed1986

Silico-acrylate contact lenses for extended wear.

Extended wear contact lenses (EWCL) have been successfully used for the correction of aphakia. Disadvantages of soft EWCL are lens precipitates, lens loss and failure to correct higher astigmatic errors. Silico-acrylate rigid EWCL with high oxygen transmissibility have been used in this study to correct aphakia and higher astigmatic errors. Fourteen eyes were fitted with Boston IV lenses and observed for a mean of 6.5 months. All patients tolerated the rigid EWCL well without important complications. One patient discontinued lens wear because of discomfort without obvious clinical abnormalities. Rigid silico-acrylate EWCL are a reliable alternative for soft EWCL and are in some cases to be preferred to soft EWCL.

Acrylates↗
PubMed1992

Clostridium neopropionicum sp. nov., a strict anaerobic bacterium fermenting ethanol to propionate through acrylate pathway.

Strain X4 was isolated several years ago from an anaerobic mesophilic plant treating vegetable cannery waste waters. It was the first example of propionic fermentation from ethanol. Morphologic and physiologic characterizations of the strain are presented here. This strain is described as type strain of a new species, Clostridium neopropionicum sp. nov. Whole cells of strain X4 ferment [1-13C] ethanol and CO2 to [2-13C] propionate, [1-13C] acetate and [2-13C] propanol, suggesting the absence of a randomizing pathway during the propionate formation. Enzymes involved in this fermentation were assayed in cell-free extracts of cells grown with ethanol as sole substrate. Alcohol dehydrogenase, aldehyde dehydrogenase, phosphate acetyl transferase, acetate kinase, pyruvate synthase, lactate dehydrogenases, and the enzymes of the acrylate pathway were detected at activities sufficient to be involved in ethanol fermentation. The same pathway may be used for the degradation of lactate or acrylate to acetate.

Acrylates↗
PubMed1992

Effects of monomeric acrylic embedding media on the antigenicity of two epitopes of the MIC2-encoded Ewing's sarcoma cell membrane antigen.

Comparative electron microscopic studies of pre- and postembedding immunolabeling experiments have shown that the antigenicity of some epitopes is lost during acrylic resin embedding of the respective tissues. In the present investigation we have tested the sensitivities of two embedding-labile epitopes (HBA-71 and HBA-45) of the Ewing's sarcoma-associated MIC2-encoded E2 antigen to the effects of the different treatment steps, which are necessary for the preparation of ultrathin sections. The extent of antigenic retention was quantitated using flow cytometry and enzyme-linked immunosorbent assays (ELISA) of tumor cell lines, thymocytes and cell membrane extracts. Fixation, dehydration and high temperature treatment of MIC2-positive cells showed only minor effects on the reactivity with the HBA-71 and HBA-45 antibodies. However, exposure of the cells to the monomeric acrylic resins LR White (LRW), LR Gold (LRG) and Lowicryl K4M at 4 degrees C for 2-18 h resulted in a significant reduction of the HBA-71 and HBA-45 reactivities. In contrast, the antigenicity of both epitopes was maintained during treatment with the apolar Lowicryl HM20 embedding medium under these non-polymerizing conditions. The resins have no direct effect on the HBA-71/HBA-45 antigen, since it could be extracted in intact form from membranes of native, but not of fixed, tumour cells using LRW for membrane solubilization. These data indicate that the HBA-71/HBA-45 antigen remains in the cell membrane and is indirectly influenced by the extraction/modification of adjacent membrane constituents. The adverse effects of the polymerization process, in the case of embedding at low temperature in Lowicryl HM20, destroyed MIC2-antigenicity.(ABSTRACT TRUNCATED AT 250 WORDS)

Acrylic Resins↗
PubMed1995

Characterization of trypsin immobilized on oxirane-acrylic beads for obtaining phosphopeptides from casein.

The aim of the study was to characterize the proteolytic properties of immobilized trypsin for obtaining phosphopeptide-rich fractions from casein. Trypsin was covalently bound to oxirane-acrylic beads. After incubation for 48 h immobilization degrees of about 85% were achieved. 20% of the immobilized enzyme exhibited no activity towards the substrate N-benzoyl-L-arginine ethyl ester. Compared with homogeneous catalysis with the soluble enzyme a 25% lower degree of proteolysis was calculated and a modified peptide pattern of the resulting proteolysates established. A caseinophosphopeptide (CPP) from alpha s1-CN (59-79) was not detectable after incubation with the carrier-bound enzyme. At a substrate concentration (S) of 15% (w/w) substrate saturation of the enzyme (E) was achieved. Increasing the substrate concentration to 20% (w/w) decreased the conversion rates (content of soluble amino-N) and the liberation of CPPs. Proteolysis of small (1% w/w) and partly also large (20% w/w) substrate concentrations (E/S = 1/100) is subject to changed kinetic conditions. The same was true for small and large enzyme concentrations (S = 5% w/w). Compared with enzyme saturation (E/S = 1/50), lack of enzyme (E/S = 1/800) led to a disproportional decrease in the proteolysis rate and to a markedly decreased content of hydrophobic peptides in the resulting proteolysates. Increasing the pH from 7.8 to 8.8 and the temperature from 37 degrees to 47 degrees C caused only a slight increase in conversion rates, but an overproportional liberation of CPPs (pH 8.8 = + 47%, 47 degrees C = +89%), in particular from beta-casein. Repeated use of immobilized trypsin resulted after nine runs in a loss in proteolytic activity and in CPP yields of approximately 25%, while the peptide pattern of the proteolysates remained qualitatively unchanged. Light microscopy shows that the oxirane-acrylic beads disintegrate to a large extent after nine repetitions.

Acrylates↗