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The reaction of a nickelalactone with dppm, resulting in the formation of a stable binuclear Ni(I) complex with an acrylate, a Ph2P- and a dppm bridge, models a key step in the formation of acrylic acid from CO2 and ethylene.
Partial or complete dentures are more commonly constructed for the elderly group of the population. Teeth debonding from the dentures can be frustrating to the patients as well as the dentist. Research has been carried out and is continuing to study the issue of bonding acrylic teeth to the denture base resin. The present review takes into account the majority of research papers published in the last five decades for determining the bond strength. Selection of more compatible combinations of denture base resins and acrylic teeth may reduce the number of prosthesis fractures and the resultant repairs.
PURPOSE: Extensive clinical investigations of the biocompatibility of different intraocular lenses (IOLs) have been made in an effort to optimize the outcome of modern cataract surgery. The aim of this study was to add animal eye experimental implantation data regarding cellular reaction on the anterior surface of IOLs. METHODS: Thirteen adult albino rabbits had phacoemulsification/aspiration of the crystalline lens followed by implantation of a posterior chamber IOL in each eye. Three types of IOLs were studied: Hydroview (Bausch and Lomb; n = 7), Acrysof (Alcon, USA; n = 7), and polymethyl methacrylate (PMMA; HOYA, Japan; n = 7). The animals were killed by intravenous pentobarbital 1, 4, or 8 weeks later. The IOLs were explanted and stained with hematoxylin and eosin, and observed under a light microscope. The shape of mouse ascites-induced macrophages on the anterior surface of the three different IOL types (Hydroview, PMMA, and Acrysof) was studied after 24 h of oven culture. RESULTS: Hydrophilic acrylic IOLs showed the highest affinity for lens epithelial cell (LEC) outgrowth, and the lowest and slowest maturation rate reaction of macrophages. PMMA IOLs showed the lowest affinity for LEC outgrowth, and the highest reaction of macrophages. Hydrophobic acrylic IOLs showed intermediate results both regarding LECs and macrophages. CONCLUSIONS: Results suggest that IOL biomaterial properties are the key factor that influences the quantity of monocytes/macrophages as well as the process of their maturation/senescence. LEC outgrowth is influenced both by the biomaterial of IOLs and by the monocyte/macrophage reaction.
Temperature- and pH-sensitive amphiphilic polymer poly(N-isopropylacrylamide-co-acrylic acid-co-cholesteryl acrylate) (P(NIPAAm-co-AA-co-CHA)) has been synthesized and employed to encapsulate paclitaxel, a highly hydrophobic anticancer drug, in core-shell nanoparticles fabricated by a membrane dialysis method. The nanoparticles are spherical in shape, and their size can be made below 200 nm by varying fabrication parameters. The lower critical solution temperature (LCST) of the nanoparticles is pH-dependent. Under the normal physiological condition (pH 7.4), the LCST is well above the normal body temperature (37 degrees C) but it is below 37 degrees C in an acidic environment (e.g. inside the endosome or lysosome). The critical association concentration of the polymer is determined to be 7 mg/L. Paclitaxel can be easily encapsulated into the nanoparticles. Its encapsulation efficiency is affected by fabrication temperature, initial drug loading and polymer concentration. In vitro release of paclitaxel from the nanoparticles is responsive to external pH changes, which is faster in a lower pH environment. Cytotoxicity of paclitaxel-loaded nanoparticles against MDA-MB-435S human breast carcinoma cells is slightly higher than that of free paclitaxel. In addition, doxorubicin is used as a probe to study cellular uptake using a confocal laser scanning microscope (CLSM). Doxorubicin molecules are able to enter the cytoplasm after escaping from the endosome and/or the lysosome. The temperature- and pH-sensitive nanoparticles would make a promising carrier for intracellular delivery of anticancer drugs.
A gas chromatographic method was developed to directly determine the enantiomers of acrylic ketone alcohol and acrylic ketone acetate. Two pairs of enantiomers were nearly baseline-separated by using Model HP-5890 Gas Chromatograph with flame ionization detector and WCOT CD-Chiral-DEX CB (30 m x 0.25 mm i.d.) column. The optimum conditions were the split ratio of 30:1 for the sample injected, the flow rates of 3.7 mL/min for the carrier gas (nitrogen), 60 mL/min for the hydrogen, and 250 mL/min for the oxygen, and temperatures of 148 degrees C for the column, 230 degrees C for the injector, and 230 degrees C for the detector. The linearity and reproducibility were satisfactory. The regression coefficients were over 0.9965. The RSDs obtained were less than 1.25%. The method was further used to trace the reactants and products, and to evaluate the enzyme catalyst activity and selectivity under different conditions. The results show that the method developed is very successful.
Acrylates and methacrylates are industrial chemicals with insufficiently known irritating and allergic effects. After considering simples monoacrylates and monomethacrylates, this paper deals with the n-ethyleneglycol acrylates and methacrylates and some polyol polyacrylates and polymethacrylates. All of the diacrylates tested are irritants for humans at 3 p. 100 in olive oil but there is no irritation at 0,1 p. 100. Monomethacrylate and dimethacrylate are not irritants at 3 p. 100 in olive oil. Studies with animals confirm that diacrylates are more irritating than dimethacrylates and the Magnusson and Kligman method shows that the substances induce delayed hypersensitivity. Cross reactions were observed in homogeneous series (diacrylates or dimethacrylates) but not between series. These results are in good agreement with clinical observations. The irritating power of 5 polyacrylates and polymethacrylates of other polyols were tested in animals. For some of them, clinical observations indicate an allergic potential.
The physiochemical properties of a hydrogel used as a scleral buckling implant for retinal detachment surgery are described. The new material was prepared by simultaneous polymerization and crosslinking of 2-hydroxyethyl acrylate with methyl acrylate and ethylene diacrylate, in the presence of an inert diluent, ethylene glycol. At equilibrium swelling, the hydrogen absorbed 17% water and had a durometer hardness (DH) of 15 (Shore Durometer A-2). A unique property of this material was its swelling hysteresis; when the gel swollen in 70% ethanol was placed in water, it retained a high level of hydration (75% water) and softness (DH 8), and most of its elasticity and strength as well. Then the swelling decreased very slowly so that the implant reached its ultimate size at equilibrium swelling in ca. 1 year. This property is especially useful in the scleral buckling procedure, in which a soft implant indents the sclera over the detached retina until reattachment is achieved. In addition to this advantage, this hydrogel is more elastic and stronger than available hydrogels of similar softness.
This paper describes several highly efficient aza-Baylis-Hillman reactions of N-tosylated imines with MVK, acrolein, and phenyl acrylate or alpha-naphthyl acrylate in the presence of a Lewis base. In most cases, the reaction can be completed within 1 h using the appropriate Lewis base catalyst. An efficient method to synthesize beta-amino ketones, aldehydes and esters in high yields and short reaction time has been developed.
The first paper of the series, which focused on the effect of polydispersity on the self-assembly of block copolymer vesicles, showed that an increase in the width of the poly(acrylic acid) (PAA) block length distribution resulted in a decrease in the size of the vesicles formed. In this paper, the rest of the phase diagram is explored. For the present study, a series of polystyrene-b-poly(acrylic acid) copolymers of an identical polystyrene length of 325 units but of varying degrees of polymerization of PAA was synthesized. Mixtures of the copolymers were made to artificially broaden the molecular weight distribution of PAA at a constant number average of 48 in the polydispersity index (PDI) range of 1.1-3.3. The mixtures were dissolved in dioxane, and water was added slowly to predetermined amounts. Transmission electron microscopy was used to observe aggregate morphologies at different water contents and PAA PDIs. At low water contents, dynamic light scattering was also used to measure the sizes of the aggregates. A partial phase diagram as a function of the water content and PAA PDI was obtained. Large compound micelles and spherical micelles (average diameter of 40 nm) were found at low water contents; however, at a water content of 12% (w/w), a continuum of morphologies from spheres to rods to vesicles was found with increasing PAA PDI. In addition, each copolymer was investigated by itself under identical conditions to those used for the mixtures to determine if there was any segregation of the individual polymers into separate aggregates. No evidence for such segregation was found.
Disk and cylindrical micellar assemblies were formed through self-organization of poly(acrylic acid)-b-poly(methyl acrylate)-b-polystyrene (PAA-b-PMA-b-PS) amphiphilic triblock copolymers with organic diamines as counterions in water/ tetrahydrofuran (THF) solvent mixtures. The system was investigated by means of transmission electron microscopy and cryogenic transmission electron microscopy. It was found that the assembled-state morphologies could be modified by alteration of the type and concentration of cationic diamine counterion undergoing interaction with the negatively charged, polyelectrolyte PAA corona block, the relative amount of water in the water/THF mixture, and the hydrophobic block chain length. Multivalency of the organic amine counterion was critical for disk formation. It was further demonstrated that a single block copolymer underwent disc-to-cylindrical micellar transitions reversibly with variation in the relative water/THF ratio. The ability to form disks beginning from either THF-rich or water-rich solutions indicated that the disk morphology was thermodynamically stable and that THF was important in keeping the micellar structure from becoming kinetically frozen. The nanoassemblies were produced having low size dispersities and were stable for at least one month. Intermediate structures between disks and cylinders were also observed, indicating two distinct kinetic pathways between the two micelle structures.
UNLABELLED: Poly(n-butylacrylate-co-carbon monoxide-co-ethylene) (polyEBC) samples prepared from 13C-labeled monomer, n-butyl acrylate, were characterized using two dimensional (2D) pulsed field gradient (PFG) 750 MHz NMR spectroscopy. To elucidate the complex structure of the terpolymer, 2D-1H/13C-heteronuclear single quantum coherence (HSQC) and heteronuclear multiple bond correlation (HMBC) experiments were conducted by selectively exciting the enhanced resonances in the spectra of two polymer samples, one polymer resulting from synthesis with 1-13C-n-butylacrylate monomer and a second polymer obtained from a synthesis with 2-13C-n-butylacrylate monomer. High-resolution 2D-NMR combined with 13C-labeling of the polymer greatly simplifies the 2D-NMR spectra, selectively enhances the weak peaks from low occurrence B-centered triad structures, and aids in their resonance assignments. In all experiments, the sample temperature was 120 degrees C, to ensure a homogeneous solution and sufficient molecular mobility. ELECTRONIC SUPPLEMENTARY MATERIAL: Supplementary material (1D 13C NMR spectra of the 13C-labeled and unlabeled polymers) is available in the online version of this article at http://dx.doi.org/100.1007/s00216-003-2402-3.
Reaction of acrylic acid (AA) at pH 7.0 and 37 degrees C for 40 days with 2'-deoxyadenosine (dAdo), 2'-deoxycytidine (dCyd), 2'-deoxyguanosine (dGuo) and thymidine (dThd) resulted in the formation of 2-carboxyethyl (CE) adducts via Michael addition. The alkylated 2'-deoxynucleoside adducts isolated (percent yield after 40 days) were 1-CE-dAdo (5%), N6-CE-dAdo (11%) (via Dimroth rearrangement of 1-CE-dAdo), 3-CE-dCyd (7.5%), 7-CE-Gua (4%), 7,9-bis-CE-Gua (0.9%) (formed by reaction of AA with depurinated 7-CE-Gua during the course of the reaction) and 3-CE-dThd (0.5%). The products isolated following in vitro reaction of AA with calf thymus DNA at pH 7.0 and 37 degrees C for 40 days were (nmol/mg DNA) 1-CE-Ade (9.9), N6-CE-Ade (8.2), 7-CE-Gua (7.2) and 3-CE-Thy (1.9). Compound 3-CE-Cyt was not detected. Thus the adducts formed following in vitro reaction of AA with DNA are identical to those formed by in vitro reaction of the carcinogen beta-propiolactone (BPL) with DNA as reported in an earlier paper. Structures were assigned on the basis of identical UV spectra, Rf values on paper chromatograms and Rt values on HPLC as marker compounds prepared from reactions of BPL with 2'-deoxynucleosides and 2'-deoxynucleotides-5'-monophosphoric acids. AA was assayed for carcinogenic activity by s.c. injection (20 mumol, once a week for 52 weeks) in female Hsd: (ICR)Br mice. Two mice with sarcomas at the site of application were observed out of 30 mice. Malignancies were not observed in solvent and no-treatment controls. The bioassay results reported in this paper and elsewhere in the same strain of mice suggest that AA is a weak carcinogen in female Hsd:(ICR)Br mice.
A method was developed for measuring the transverse strength of repaired acrylic samples at a single butt joint. The strength was determined for samples prepared from two types of heat polymerizing resins and two types of repair resins. The temperature elevation during curing of the repair resins was determined. Cross-linking of the resins was evaluated by immersion of samples in solvents. The appearance of the bead microstructure after various treatments was considered to indicate relaxation at the sample surface. Repaired samples of the heat polymerizing resin which exhibited relaxation after immersion in monomer, had a lower strength than samples prepared from the resin for which relaxation was not observed, although both resins were cross-linked to a similar extent. The application of pressure during curing increased the strength of the samples repaired with the rapid curing, cross-linked, repair resin. The strength of the samples repaired with the uncross-linked, slow curing, repair resin was affected by pressure only if the insertion of the repair resin between the sample parts was delayed after mixing. Variations in the powder to liquid ratio of the uncross-linked repair resin did not affect the sample strength. Wetting of the sample parts with monomer before repair, and variations in the curing temperature did not affect the sample strength for the investigated resin combinations.
1. The relative binding constants of four drugs to charcoal, silicone oil silicas and acrylate copolymers was studied using an in-vitro binding technique. 2. The maximum adsorption capacity (K2) was chosen as a measure of the degree of binding and calculated by fitting to the Langmuir equation. 3. Charcoal alone was shown to be the most effective of the adsorbents chosen. The possible use of silicone oils as an adsorbent delivery vehicle in treatment of overdose is discussed.
The syntheses and polymerizations of acrylate (ASOE) and methacrylate (MASOE) containing spiro ortho ester moieties were carried out and the properties of the polymers obtained were investigated. The ring-opening reaction of the spiro ortho ester groups proceeded well during heat polymerization (HC) with the ionic initiators (BSS and HPSS). However, a small amount of unreacted carbon-carbon double bond was observed in the polymers obtained. Not only vinyl polymerization but also a small amount of ring-opening reaction took place during polymerization with radical initiators (BPO, AIBN, DTB and CQ). The poly-(MASOE)s obtained by HC with BSS, BSS/AIBN and BSS/BPO were plastic like polymers. Low volume shrinkage was observed during HC and UVLC of ASOE and MASOE with ionic initiators. These shrinkages were smaller than those of conventional methacrylate.
A novel iodine-containing methacrylate, 2,5-diiodo-8-quinolyl methacrylate, has been synthesized and used in the preparation of acrylic radiopaque cements. The effect of incorporation of this monomer to the self-curing resins, on the curing parameters, swelling behaviour and mechanical properties was studied. The incorporation of the radiopaque compound 2,5-diiodo-8-hydroxyquinoline to the solid phase was also carried out for comparative experiments. A decrease in the peak temperature and an increase in the setting time was observed with the addition of the radiopaque monomer, however, the curing parameters did not appreciably change with the addition of the radiopaque compound to the solid phase. Swelling of the modified cements was in the same range as that of the radiolucent cement; however, the diffusion coefficients calculated according to the Fick's law were higher for the iodine-containing materials. The addition of 5 wt% of the iodine-containing methacrylate provided a significant increase in the tensile properties with respect to either control radiolucent formulations or BaSO4-containing formulations. Biocompatibility of the modified cements was studied by implantation of rods of the cements into rats and histological analysis of the surrounding tissue.
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