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PubMed2005

(1)H and (13)C NMR chemical shifts of methacrylate molecules associated with DMPC and/or DPPC liposomes.

In the light of recent developments, changes in (1)H and (13)C NMR chemical shifts of methacrylate molecule associated with DMPC (L-alpha dimyristoylphosphatidylcholine) or DPPC (L-alpha-dipalmitoylphosphatidylcholine) liposomes as a model for mimic native lipid bilayers were studied at 30, 37, and 52 degrees C. The chemical shifts of 3Ha, 3C, and 4C resonances in methacrylates (see Fig. 2) were greatly shifted higher field, suggesting the methacrylate molecule-lipid bilayer interaction. Comparison of the findings with methyl methacrylate (MMA), ethylene dimethacrylate (EDMA), and triethyleneglycol dimethacrylate (TEGDMA) revealed that the interaction of dimethacrylates (EDMA, TEGDMA) was greater than monomethacrylate, MMA. Their interaction with DMPC liposomes was also judged by a differential scanning calorimetry (DSC), indicating that the interaction was characterized by decreasing the enthalpy, entropy, and transition co-operativity. The evidence of the upfield NMR-shifts for methacrylate molecules was also judged by the descriptors such as the reactivity (HOMO-LUMO energy) and the electrostatic function (partial charges) between methacrylate molecules and DPPC, calculated by a PM 3 semiempirical MO method. The upfield NMR shifts were considerably well interpreted from the descriptors. NMR screening technique in methacrylates to phospholipid targets would be highly valuable in biomaterial developments. Figure 2 Changes in (1)H and (13)C NMR chemical shifts of methacrylate molecule associated with DMPC or DPPC liposomes. DMPC liposomes/MMA (1:1, molar ratio) and DMPC/TEGDMA (1:1) liposomes were measured at 30 degrees C. In DPPC liposome system, the rippled gel phase was measured at 30 degrees C, whereas the liquid crystalline phase for MMA and for both EDMA and TEGDMA were measured at 52 degrees C and 37 degrees C, respectively.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1997

Cytotoxic effects of acrylates and methacrylates: relationships of monomer structures and cytotoxicity.

Thirty-nine acrylates and methacrylates that had been used in dental resin materials were evaluated by a cytotoxicity test, and the relationships between their structures and cytotoxicity were studied to predict cytotoxic levels of dental resin materials in order to develop new low-toxic resin materials. All the acrylates evaluated were more toxic than corresponding methacrylates. In both the acrylates and methacrylates, a hydroxyl group seemed to enhance cytotoxicity. Dimethacrylates with 14 or fewer oxyethylene chains showed similar cytotoxicity while dimethacrylates with 23 oxyethylene chains showed lower cytotoxicity. The cytotoxicity ranking of monomers widely used in dental resin materials was bisphenol A bis 2-hydroxypropyl methacrylate (bisGMA) > urethane dimethacrylate (UDMA) > triethyleneglycol dimethacrylate (3G) > 2-hydroxyethyl methacrylate (HEMA) > methyl methacrylate (MMA). In acrylates, methacrylates, and ethylmethacrylates with either substituents, the lipophilicity of substituents affected their cytotoxicity, and an inverse correlation between IC50 and logP was observed. These results will be useful in developing new resin materials with low toxic monomer compositions.

Acrylates↗
PubMed1989

Cross-linking and ring opening during polymerization of heterocyclic methacrylates and acrylates.

Heterocyclic methacrylates have been shown to have low polymerization shrinkage. In this paper, the extent of ring opening has been assessed by the degree of consequent cross-linking. In polymers of tetrahydrofurfuryl methacrylate and acrylate, tetrahydropyranyl and tetrahydropyran-2-ylmethyl methacrylate, fewer than 1% monomer units were involved in cross-linking and hence ring-opening reactions. 2-epoxypropyl methacrylate, when polymerized, was very extensively cross-linked indicating prolific ring opening. However, the polymerization shrinkage of this material was the highest of the heterocyclic methacrylates studied and was that predicted from the known molar volume change of methacrylate esters. Ring opening does not, therefore, appear to be a significant factor in the polymerization shrinkage of heterocyclic methacrylates.

Acrylates↗
PubMed2004

Methacrylates in dental restorative materials.

Commercial dental restorative materials were analysed in order to obtain information about the occurrence of sensitizing acrylates. Acetone-soluble methacrylates of 7 bonding materials, 8 composite resins and 2 glass ionomers were identified by gas chromatography with mass-selective detection and quantified by liquid chromatography with ultraviolet detection. The most frequently occurring methacrylates in the bonding materials were 2-hydroxyethyl methacrylate (2-HEMA) and 2,2-bis-[4-(2-hydroxy-3-methacryloxypropoxy)phenyl]-propane (bis-GMA). Bis-GMA and triethyleneglycol dimethacrylate were the most frequently occurring methacrylates in composite resins. The main methacrylate of the 2 glass ionomers was 2-HEMA or trimethylolpropane trimethacrylate. Information about methacrylates was given in the safety data sheets (SDSs) for about half of the products that according to the analysis results contained methacrylates. SDSs need to be improved so that the health risks for dental personnel can be reliably assessed and controlled.

Dental Materials↗
PubMed1998

Staining tissue with methacrylate casts for light microscopy.

Scanning electron microscopy (SEM) of methyl methacrylate casts and light microscopy (LM) of tissue are well-established methods for studying the microcirculation. The two are complimentary, but methacrylate is transparent and thus its presence is often not appreciated by LM. Applying histologic stains to sections of tissue embedded in methyl methacrylate would allow the relationships of light microscopic and scanning electron microscopic views of cast vasculature to be better appreciated. We sought to test different stains on cast tissue to find one that would accent the cast. Surgically removed and autopsied human lungs were cast with methacrylate and processed by routine light microscopic methods. They were stained with the hematoxylin and eosin, Masson trichome, elastic--van Gieson, Grocott methenamine silver, Brown-Brennan, and Ziehl-Neelsen methods. The Ziehl-Neelsen procedure stained the methacrylate best, giving it a red color. This procedure also worked well without heating. We conclude that (1) cast methacrylate lung can be processed for routine LM with excellent results; (2) methacrylate stains well with the Ziehl-Neelsen technique; (3) the acid--fast stained cast lung shows capillaries and cells in both normal and diseased lung better than the routine hematoxylin and eosin stain; (4) this technique can be used to assess filling and correlate findings on the same tissue with the two different microscopic methods.

Corrosion Casting↗
PubMed1980

Enzymatic addition of modified cytosine nucleotides to DNA. Methacrylate polymerization by an azo pyrimidine.

An azo pyrimidine that induces the polymerization of 1-glyceryl methacrylate has been prepared. 1-Glyceryl methacrylate contains substituent glycol groups for binding heavy atoms for subsequent electron microscopic studies. Oxodation of 1-methyl N4-ureidocytosine (compound 1A) with N-bromosuccinimide produced 4-aminocarbonylazo-2-pyrimidinone (compound 2A). This orange compound shows a broad peak (lambda max = 349 nm) in its ultraviolet absorption spectrum. Mixing compound 2A with mildly acidic aqueous solutions of 1-glyceryl methacrylate (pH 3.6) resulted in polymerization of the methacrylate. Under these conditions, the ester 1-glyceryl methacrylate does not hydrolyze appreciably as judged by oxidation of the glycol groups with NaIO4 and spectrophotometric analysis of the HCHO liberated using Schiff's reagent. Attachment of azo nucleotides to the 3'-terminus of DNA was achieved in two steps. First, N4-ureidocytosine deoxynucleotides were enzymatically added to single strand DNA primers using calf thymus terminal deoxynucleotidyl transferase, Co2+, and N4-ureido-2'-deoxycytidine 5'-triphosphate (prepared by the HSO3--catalyzed transamination reaction of dCTP with semicarbazide). Second, these modified nucleotides were oxidized with N-bromosuccinimide to produce DNA that contained azo pyrimidine nucleotides at its 3'-end (azoDNA). Upon adding acid to the azoDNA, the azo nucleotides decomposed. If these nucleotides induce methacrylate polymerization upon decomposition as did compound 2A, it may be possible to mark the location of DNA termini in situ for electron microscopy by attaching heavy atoms to the poly(1-glyceryl methacrylate) formed. Such studies may elucidate the nature and location of the ends of the eukaryotic chromosomal DNA molecule in both chromosomes and interphase nuclei.

Acrylic Resins↗
PubMedDate not supplied

Biomimetic poly(methyl methacrylate)-based terpolymers: modulation of bacterial adhesion effect.

Adherence of Staphylococcus aureus, responsible for major foreign body infections, was assessed onto functionalized poly(methyl methacrylate)-based terpolymers bearing sulfonate and carboxylate groups and onto poly(methyl methacrylate) as control. These terpolymers, have been synthesized by radical copolymerization of methyl methacrylate, methacrylic acid, and sodium styrene sulfonate by varying the ratio R = [COO(-)]/[COO(-) + SO(3)(-)] from 0 to 1 and keeping ionic monomer content between 7 and 18%. Adsorption of fibronectin onto poly(methyl methacrylate) was shown to dramatically promote bacterial adherence, whereas a strong inhibition of bacteria adherence was observed onto functionalized terpolymers containing both carboxylate and sulfonate groups. When terpolymers were predominantly functionalized by carboxylate groups, bacteria adherence was favored and reached values close to those obtained for poly(methyl methacrylate). These results have been related to the distribution of the anionic groups along the macromolecular chains, creating active sites responsible for specific interactions with fibronectin and inducing modifications of its conformation. The conformation of the adsorbed adhesive protein was then suggested to have an influence on the availability of its interaction sites to bacteria adhesins and therefore on modulation of bacteria adherence. Inhibition of Staphylococcus aureus adherence by functionalized poly(methyl methacrylate)-based terpolymers is of great interest in the field of biomedical implants and especially in the case of ophthalmic applications.

Bacterial Adhesion↗
PubMedDate not supplied

Synthesis and aqueous solution properties of novel sugar methacrylate-based homopolymers and block copolymers.

We report the facile preparation of a range of novel, well-defined cyclic sugar methacrylate-based polymers without recourse to protecting group chemistry. 2-Gluconamidoethyl methacrylate (GAMA) and 2-lactobionamidoethyl methacrylate (LAMA) were prepared directly by reacting 2-aminoethyl methacrylate with D-gluconolactone and lactobionolactone, respectively. Homopolymerization of GAMA and LAMA by atom transfer radical polymerization (ATRP) gave reasonably low polydispersities as judged by aqueous gel permeation chromatography. A wide range of sugar-based block copolymers were prepared using near-monodisperse macroinitiators based on poly(ethylene oxide) [PEO], poly(propylene oxide) [PPO], or poly(e-caprolactone) [PCL] and/or by sequential monomer addition of other methacrylic monomers such as 2-(diethylamino)ethyl methacrylate [DEA], 2-(diisopropylaminoethyl methacrylate [DPA], or glycerol monomethacrylate [GMA]. The reversible micellar self-assembly of selected sugar-based block copolymers [PEO23-GAMA50-DEA100, PEO23-LAMA30-DEA50, PPO33-GAMA50, and PPO33-LAMA50] was studied in aqueous solution as a function of pH and temperature using dynamic light scattering, transmission electron microscopy, surface tensiometry, and 1H NMR spectroscopy.

Carbohydrates↗
PubMed1983

Initiating polymerization of glycol methacrylate with cyclic diketo carbon acids.

Several pharmacologically active cyclic diketone carbon acids, including phenylbutazone and 2-phenyl-1,3-indandione, catalyze the polymerization of glycol methacrylate monomers. GMA-cyclic diketone carbon acid monomer mixtures incorporating imidazole polymerize smoothly without obvious exothermicity at temperatures ranging from ambient to -5 C without the use of ultraviolet light. The only equipment required for this embedding technique is a refrigerator with a freezing compartment which can maintain temperatures of -15 C. A recipe consisting of 5 ml glycol methacrylate (2-hydroxyethyl methacrylate), 0.8 ml 1-pentanol, 16 mg imidazole, and 30 mg monophenylbutazone is recommended for general use. The use of dicyclopentyl methacrylate-glycol methacrylate comonomer mixtures incorporating cyclic ketone catalysts is advocated, as blends of these monomers have low basophilia, and tissues embedded in these matrices stain sharply and brilliantly. It is hypothesized that the driving force for the cyclic ketone-mediated polymerization of glycol methacrylate under basic conditions is furnished by the lysis of cyclic ketone carbon acid peroxides.

Acrylates↗
PubMed2001

Periplasmic methacrylate reductase activity in Wolinella succinogenes.

The cell homogenate and the soluble cell fraction of Wolinella succinogenes grown with formate and fumarate catalyzed the oxidation of benzyl viologen radical by methacrylate [apparent Km=0.23 mM, Vmax=1.0 U (mg cell protein) -1] or acrylate [apparent Km=0.50 mM, Vmax=0.77 U (mg cell protein) -1]. Crotonate did not serve as an oxidant. A mutant of W. succinogenes lacking the fccABC operon was unable to catalyze methacrylate or acrylate reduction. In contrast, the inactivation of fccC alone had no effect on these activities. Methacrylate reduction by benzyl viologen radical was not catalyzed by fumarate reductase isolated from the membrane of W. succinogenes. Cells grown with formate and fumarate did not catalyze methacrylate reduction by formate, and W. succinogenes did not grow with formate and methacrylate as catabolic substrates. The results suggest that the reduction of methacrylate or acrylate by benzyl viologen radical is most likely catalyzed either by the periplasmic flavoprotein FccA or by a complex consisting of FccA and the predicted c-type cytochrome FccB. The metabolic function of the fccABC operon remains unknown.

Cell Membrane↗
PubMed2000

Release of methacrylic acid from dental composites.

OBJECTIVE: The aim of this study was to investigate the release of methacrylic acid from four commercial dental composite restoratives (Silux Plus (3M), Z100 (3M), Ariston pHc (Vivadent) and Surefil (Dentsply)). METHODS: Three specimen disks (10(0.2) mm in diameter and 2(0.2) mm thick), were prepared for each material using custom-made molds. Each disk was placed in artificial saliva for 24 h at 37 degrees C, rinsed and subsequently immersed in 1.5 ml of deionised water in an airtight glass container. The container was continuously shaken at a speed of 80 rpm for 24 h at 37 degrees C in an orbital incubator. After 24 h (Day 1), the water was removed and analyzed. The specimen disk was then re-immersed into another 1.5 ml of fresh deionised water. The procedure of removing and refilling of the water was repeated for a total of 7 days. The sample solutions were filtered and injected into the capillary electrophoresis system for analysis immediately after collection. Statistical analysis was performed by ANOVA and Scheffe's test. RESULTS: For Days 1-7, methacrylic acid released in water at 37 degrees C by Ariston was significantly greater than that of the other composites. Ranking from least to greatest total (cumulative over 7 days) methacrylic acid release was as follows: Z100 (5.66 ppm) < Silux (8.81 ppm) < Surefil (20.21 ppm) < Ariston (519.04 ppm). Methacrylic acid release was greatest at Day 1 for all materials and generally decreased with time. SIGNIFICANCE: Some composites may release high levels of methacrylic acid. The biological effects of such high levels of methacrylic acid is not known and warrant further in vivo and in vitro investigations.

Analysis of Variance↗
PubMed2001

Methyl methacrylate toxicity in rat nasal epithelium: studies of the mechanism of action and comparisons between species.

Female F344 rats exposed to 200 ppm methyl methacrylate for 6 h developed a lesion in the nasal olfactory epithelium which was characterised by degeneration and atrophy. The severity of the lesion was markedly reduced by pre-treatment of the rats with an intraperitoneal dose of 100 mg/kg bis-(p-nitrophenyl)phosphate, an inhibitor of carboxylesterase enzymes, thus demonstrating that the lesion is caused by the carboxylesterase mediated metabolism of methyl methacrylate to methacrylic acid, an irritant and corrosive metabolite. The distribution of the carboxylesterases in nasal tissues has been investigated and the metabolism of methyl methacrylate to methacrylic acid has been compared in rat, hamster and human nasal tissue fractions in vitro. Histocytochemistry showed that the carboxylesterases are heavily localised in the sustentacular cells and Bowman's glands of the rat olfactory region, but are more generally distributed in human olfactory epithelium. Consistent with this, the enzyme activity in all three species was higher in fractions prepared from olfactory tissue than from respiratory tissue, 3-fold in rat and human and 12-fold in the hamster. The maximum rates (V(max)) of metabolism in rat and hamster olfactory tissue fractions were comparable, whereas those in human olfactory tissue fractions were at least 13-fold lower. The rate of metabolism in rat olfactory tissue was also comparable to that in rat liver whereas in humans, the rate in olfactory tissue was 500-fold lower than that in the liver. In respiratory tissues, the rate in humans was at least 6-fold lower than that in the rat. These results suggest that humans are significantly less sensitive than rodents to the nasal toxicity of methyl methacrylate.

Animals↗
PubMed2000

Carbohydrate/monomer complexes in aqueous polymerizations: methylated-beta-cyclodextrin mediated aqueous polymerization of hydrophobic methacrylic monomers.

Hydrophobic methacrylic monomers were polymerized in aqueous media using methylated (1.8)-beta-cyclodextrin (MeCD) additives. Hydrophobic monomers tert-butyl methacrylate (tBuMA), cyclohexyl methacrylate (CMA), and 2-ethylhexyl methacrylate (2EHMA) were each dissolved in chloroform with MeCD. Chloroform was then evaporated to yield solid monomer/cyclodextrin complexes. Complexes were shown by 1H NMR and thermogravimetric analysis (TGA) to have molar ratios of monomer to MeCD as high as 0.72/1.00. The water-soluble complexes were readily polymerized in aqueous media using free radical initiation. During polymerization, hydrophobic methacrylic polymers precipitated and the majority of MeCD remained in solution. Poly(alkyl methacrylates) synthesized via this method exhibited number-average molecular weights ranging from 50,000 to 150,000 with polydispersities from 3.2 to 5.5 depending on monomer structure, and isolated yields were as high as 86%. Additionally, corresponding methacrylic/carbohydrate films were prepared and examined. High molecular weight poly(tBuMA), poly(CMA), and poly(2EHMA) were blended with MeCD to produce optically clear films with as high as 20 wt % MeCD. Differential scanning calorimetry (DSC) characterization indicated that the glass transition temperatures of these novel carbohydrate blends were controllable over a 20 degrees C range depending on the relative concentration of each component.

Carbohydrates↗
PubMed1997

Inulin hydrogels as carriers for colonic drug targeting: I. Synthesis and characterization of methacrylated inulin and hydrogel formation.

PURPOSE: Vinyl groups were introduced in inulin chains in order to form hydrogels of this sugar polymer by free radical polymerization. METHODS: Inulin was reacted with glycidyl methacrylate in N,N-dimethylformamide in the presence of 4-dimethylaminopyridine as catalyst. 1H and 13C NMR spectroscopy were used for the characterization of the obtained reaction product. Solid state 13C NMR spectroscopy revealed the conversion of the incorporated vinyl groups into covalent cross-links upon free radical polymerization of aqueous solutions of the derivatized inulin. RESULTS: During reaction of inulin with glycidyl methacrylate, transesterification occurred, leading to the direct attachment of the methacryloyl group to inulin. Consequently, the obtained reaction product is methacrylated inulin. The extent of chemical modification of inulin could be tuned by varying the molar ratio of glycidyl methacrylate to inulin in the reaction mixture. Aqueous solutions of methacrylated inulin were converted into cross-linked hydrogels by free radical polymerization using ammonium persulphate and N,N,N',N'-tetramethylethylenediamine as initiating system. CONCLUSIONS: Inulin hydrogels can be formed by free radical polymerization of aqueous solutions of methacrylated inulin.

4-Aminopyridine↗
PubMed1983

Permeability of surgeons' gloves to methyl methacrylate.

The quick passage of methyl methacrylate at 21 degrees C and 35 degrees C through seven surgeon's glove materials in a diffusion chamber was quantified by gas-chromatographic analysis. Polystyrene-butadiene dissolved in methyl methacrylate, latex and polychlorobutadiene showed reversible expansion, during which material from the samples dissolved. In order to prevent these phenomena from interfering with the analyses, experiments were performed with 4.7 M methyl methacrylate in ethanol. Even then, the time in which methyl methacrylate permeated the membrane was too short for sufficient protection. When using these gloves, the orthopaedic surgeon who is fixing endoprostheses is no doubt occlusively exposed to methyl and other methacrylates, benzoyl peroxide, rubber additives, etc. Of glove materials which are not surgically used, vinyl was inferior to latex, whereas a very thin polyethylene copolymer did not change in methyl methacrylate, showed better resistance to diffusion, but was insufficiently elastic and easily perforated. A better protective material is urgently needed.

Bone Cements↗
PubMed1991

Lack of immune response to methyl methacrylate in lymphocyte cultures.

To analyze whether or not methyl methacrylate is immunologically inert, peripheral blood mononuclear cells were cultured with finely pulverized methyl methacrylate. Phytohemagglutinin (PHA) lectin, purified protein derivate of tuberculin (PPD) antigen, and culture medium alone were used as positive and negative controls. Lymphocyte kinetics on culture Days 0, 1, 3, and 5 were studied. Major histocompatibility complex locus II antigen (MHC locus II antigen; Ia) and interleukin-2 receptor (IL-2R; Tac) expression were analyzed using the avidin-biotin-peroxidase complex (ABC) method and lymphocyte DNA synthesis using 3H-thymidine incorporation and beta-scintillation counting. On culture Days 1 and 3, lymphocytes and monocytes were seen under the light microscope to be attached to methyl methacrylate particles. However, the results disclosed no methyl methacrylate-induced DNA synthesis, although methyl methacrylate-induced MHC locus II antigen and IL-2R activation marker expression were recorded; notably, this expression was less pronounced than that seen in PHA or PPD antigen driven lymphocyte response. The results suggest that methyl methacrylate is essentially an immunologically inert implant material. However, it seems to induce inflammatory mononuclear cell migration and adhesions leading to slightly nonspecific lymphocyte reaction.

Bone Cements↗
PubMedDate not supplied

The effect of steam autoclave sterilization on methyl methacrylate cranial implant materials.

The use of methyl methacrylates for cranial repairs has been well established. Procedures for sterilization of these materials include soaking in benzalkonium chloride, use of ethylene oxide gas, or cobalt 60 irradiation. Although ethylene oxide sterilization is the most common method, gas sterilization and degassing of these prefabricated implants may require almost as much time as fabrication. This study evaluated impact strength and linear dimensional change following steam autoclave sterilization of heat-processed methyl methacrylate. It was compared to an autopolymerizing methyl methacrylate for impact strength. No statistical difference was found in impact strength between nonsterile heat-processed methyl methacrylate and autoclaved heat-processed methyl methacrylate; however, both were significantly stronger than the autopolymerizing material. A statistically significant linear dimensional change of 1.211% between the autoclaved and nonsterile heat-processed methyl methacrylate was found, but was not considered clinically significant.

Analysis of Variance↗
PubMed1984

The siloxane bond in contact lens materials: the siloxanyl alkyl methacrylate copolymers.

The siloxanyl alkyl methacrylate copolymers with methyl methacrylate and other components including hydrophilic monomers and crosslinking agents are used to make siloxane methacrylate oxygen-permeable rigid contact lenses. These copolymers contain the element silicon as siloxane bonds in side branches of the main polymer chain, which is made of carbon-to-carbon bonds. The siloxane bonds are the main contributing factor to the oxygen permeability of these materials. Because silicone is not a component of these contact lenses, it is not appropriate to refer to them as silicone methacrylate contact lenses. This paper analyzes data from three fundamental patents and gives the oxygen permeability coefficients of three types of siloxanyl alkyl methacrylate copolymers. In one type the siloxanyl component contains two silicon atoms, in the second type it contains three silicon atoms, and in the third type it contains four silicon atoms. A general relationship, expressed by a power function, is developed between the oxygen permeability coefficients of siloxanyl alkyl methacrylate copolymers and dimethylsilicone rubber and their percent disiloxane or silicon content.

Chemical Phenomena↗