Enzymatic acrylation of 2-hydroxy-γ-butyrolactone to synthesize the gamma butyrolactone methacrylate (GBLMA) for photoresist

Lipase-mediated acrylation has gained much attention instead of traditional chemical process, since it enables specific catalysis under benign conditions. The effect of acyl donors on the acrylation of 2-hydroxy-γ-butyrolactone by Novozym 435 (immobilized lipase B from Candida antarctica) was investigated. Among acyl donors, vinyl methacrylate was selected to synthesize γ-butyrolactone methacrylate (GBLMA). The effects of solvent and reaction temperature on the acrylation using vinyl methacrylate were presented. The highest rate of conversion was obtained using methyl tert-butyl ether (>80%) as a solvent, of which a log P value is greater than other solvents tested. The conversion rate increased as the reaction temperature rose from 30 to 60°C and the conversion rate approached 95% at 60oC. The gamma butyrolactone methacrylate (GBLMA) synthesized with vinyl methacrylate at optimized conditions, in which MTBE is used as a solvent and the reaction is carried out at 60°C can be applicable as a monomer for synthesis of photoresist resin.     

Effect of reaction parameters on synthesis of citronellyl methacrylate by lipase-catalyzed transesterification

The methacrylate ester of citronellol was synthesized using various lipases as catalyst. The effect of different reaction parameters such as amount of lipase, solvent, temperature, and acylating agent on the conversion of citronellol to citronellyl methacrylate was studied. Methyl methacrylate, vinyl methacrylate, and 2,3-butanedione mono-oxime methacrylate were used as acylating agents. Porcine pancreatic lipase (PPL), Candida rugosa lipase (CRL), and Pseudomonas cepacia lipase (Amano-PS) were used as biocatalysts. Diisopropyl ether (DIPE) was found to be the most suitable solvent. The stereoselectivity of CRL in transesterification of (+/-)-citronellol was tested for the optimized reaction parameters.     

Disposable luciferase‐based microfluidic chip for rapid assay of water pollution

In the present study, we demonstrate the use of a disposable luciferase‐based microfluidic bioassay chip for environmental monitoring and methods for fabrication. The designed microfluidic system includes a chamber with immobilized enzymes of bioluminescent bacteria Photobacterium leiognathi and Vibrio fischeri and their substrates, which dissolve after the introduction of the water sample and thus activate bioluminescent reactions. Limits of detection for copper (II) sulfate, 1,3‐dihydroxybenzene and 1,4‐benzoquinone for the proposed microfluidic biosensor measured 3 μM, 15 mM, and 2 μM respectively, and these values are higher or close to the level of conventional environmental biosensors based on lyophilized bacteria. Approaches for entrapment of enzymes on poly(methyl methacrylate) (PMMA) plates using a gelatin scaffold and solvent bonding of PMMA chip plates under room temperature were suggested. The proposed microfluidic system may be used with some available luminometers and future portable luminescence readers.     

Design,Characterization, and Evaluation of Meloxicam Gel Prepared by Suspension and Solution Polymerization Using Solubility Parameter as the Basis for Development

Meloxicam gel was designed based on the matching of the solubility parameter (δ) of the drug with that of the polymer and subsequently with skin for improved dermal delivery of meloxicam. The δ of meloxicam (11.48 (cal/cm³)^0.5) determined by solubility measurement was matched statistically to the solubility parameter of monomers, n-vinyl-2-pyrrolidone, polyvinyl alcohol (PVA), hydroxyl ethyl methacrylate, ethylene glycol methacrylate (EGMA) determined by intrinsic viscosity measurement. Consequently gels were formulated by polymerization in selected solvent blend of water/ethyl acetate (20:80) in which the drug showed maximum solubility. Thus, F1–F16 formulations designed were evaluated for physicochemical properties, textural analysis, and in vitro drug release. On the basis of optimum characteristics, F2 (PVA, δ = 16.96 (cal/cm³)^0.5) and F8 (EGMA, δ = 18.35 (cal/cm³)^0.5) formulated by suspension polymerization were selected and subjected to skin irritation and topical anti-inflammatory studies. The formulation F8 demonstrated significant (p < 0.05) of anti-inflammatory activity in comparison to marketed piroxicam gel and was free from irritation.     

Effect of pre-processing methods on bond strength between acrylic resin teeth and acrylic denture base resin

doi: 10.1111/j.1741‐2358.2011.00480.x
Effect of pre‐processing methods on bond strength between acrylic resin teeth and acrylic denture base resin Objectives: This study evaluated the effects of various pre‐processing methods on the bond strength between resin and denture teeth. Backgrounds: Debonding of acrylic resin teeth from denture base material is a problem for patients wearing complete dentures. Materials and Methods: Four experimental groups (n = 30) were investigated by subjecting tooth–resin bonding to tensile loading. Specimens were prepared and tested according to the methods of the International Standards Organization (ISO 22112:2005) using a special assembly. Four pre‐processing surface treatments of teeth were applied: (i) ST₁, no treatment applied (control); (ii) ST₂, wax solvent (Dewaks, Faber Kimya & Ilaç, Turkey); (iii) ST₃, boiling water followed by conditioning with methyl methacrylate (MMA) monomer (Meliodent, Bayer Dental, Germany); (iv) ST₄, boiling water followed by wax solvent agent and finally MMA monomer application. Bond strength test was performed using a universal testing machine. Results: All the strength values of the test groups were within clinically acceptable limits. The lowest values were from the ST₁ group and the highest values were in the ST₄ group. Conclusions: Wax elimination methods affected bonding strength. Application of wax solvent and MMA monomer to the ridge lap surfaces of the teeth gave the best results. In clinical practice, this application procedure may decrease the bonding failure of denture teeth.     

Multi‐steps green process for synthesis of six‐membered functional cyclic carbonate from trimethylolpropane by lipase catalyzed methacrylation and carbonation,and thermal cyclization

A highly functionalized six‐membered cyclic carbonate, methacrylated trimethylolpropane (TMP) cyclic carbonate, which can be used as a potential monomer for bisphenol‐free polycarbonates and isocyanate‐free polyurethanes, was synthesized by two steps transesterifications catalyzed by immobilized Candida antarctica lipase B, Novozym^®435 (N435) followed by thermal cyclization. TMP was functionalized as 70 to 80% selectivity of mono‐methacrylate with 70% conversion was achieved, and the reaction rate was evaluated using various acyl donors such as methacrylic acid, methacrylate‐methyl ester, ‐ethyl ester, and ‐vinyl ester. As a new observation, the fastest rate obtained was for the transesterfication reaction using methacrylate methyl ester. Byproducts resulted from leaving groups were adsorbed on the molecular sieves (4Å) to minimize the effect of leaving group on the equilibrium. The difference of reaction rate was explained by molecular dynamic simulations on interactions between carbonyl oxygen and amino acid residues (Thr 40 and Glu 157) in the active site of lipase. Our docking studies revealed that as acyl donor, methyl ester was preferred for the initial conformation of the first tetrahederal intermediate with hydrogen bonding interactions. TMP‐monomethacrylate (TMP‐mMA) cyclic carbonate was obtained in 63% yield (74.1% calculated in 85% conversion) from the lipase‐catalyzed carbonation reaction of TMP‐mMA with dimethylcarbonate, and followed by thermal cyclization of the monocarbonate at 90°C. From the multiple reactions demonstrated in gram scale, TMP‐mMA cyclic carbonate was obtained as a green process without using chlorinated solvent and reagent. © 2015 American Institute of Chemical Engineers Biotechnol. Prog., 32:83–88, 2016     

Molecular Mobility in Poly(butyl methacrylate) and Poly(methyl methacrylate)

Molecular mobility is studied in poly(butyl methacrylate) and poly(methyl methacrylate) (PMMA) with molecular dynamics simulations in order to understand the effect of the α–β crossover on the β relaxation activation energy and co-operativity. In the high frequency range investigated, the estimated β process activation energy is decreased as compared to the low frequency value. This deviation is stronger in poly(n butyl methacrylate) (PnBMA) than in PMMA. The intra-molecular co-operativity related to the β process is also higher in PnBMA than in PMMA. These results could be related to the relative position of the simulation temperature range and of the extrapolated α–β crossover temperature.     

Evidence for heterogeneity in DNA-associated solvent mobility from acridine phosphorescence spectra

The mobility of solvent associated with native DNA in comparison with that of the bulk solvent is monitored from the temperature-dependent red shift in the phosphorescence spectra of acridines bound to DNA and free in glycol–buffer mixtures. Over the temperature range for which the red shift occurs the phosphorescence decay changes with emission wavelength, indicating the time-dependent nature of the process. Moreover, at these temperatures, emission anisotropy measurements establish that motions of the dye itself are not involved. Correspondence between perturbations to the solvent that influence the temperature at which the red shift occurs for free acridine with those for the DNA-bound dye confirm that “bound solvent” is responsible for the spectral changes. For the DNA-bound acridines the extent of the red shift is smaller and the midpoint T_1/2 of the transition is warmer. The reduction in the red shift reveals that the bound dye is less exposed to solvent and varies as 9-aminoacridine < acridine orange ～ proflavin, i.e., 9-amino-acridine is less exposed to solvent. On the other hand, the warmer T_1/2 indicates that DNA-associated solvent is considerably less mobile than bulk solvent. T_1/2 varies for proflavin bound to DNA, poly[d(AT)], poly[d(GC)], and poly(dG): poly(dC), and for proflavin, acridine orange, and 9-aminoacrine bound to DNA. These observations suggest that there is a heterogeneity in the mobility of DNA-associated solvent.     

Solvent Effects on the Shape of a Tetramer

Abstract

The solvent effect on the shape of a tetramer with increasing temperature is analyzed. For this purpose models of an isolated chain and a chain immersed in a solvent have been simulated by Molecular Dynamics. A solvent model represented by stochastic forces has been tested against molecular dynamics results. The behaviour of the mean-square end-to-end distance 〈R ²〉 and 〈l ₁ ³ S ²〉 with increasing temperature are shown. where l ₁ is the longest eigenvalue of the moment of inertia tensor and S is the radius of gyration. All the chain models studied show different behaviour of these quantities at low temperature compared to high temperature where the shape of the tetramer is temperature insensitive. The main solvent effect is to pospone the transition to higher temperature. The stochastic solvent model qualitatively agrees with molecular dynamics results.     

Synthesis and chemiluminescence of copolymers of 5-amino-8-vinyl-phthalazine-1, 4(2H,3H)-dione with methyl methacrylate or styrene,and of α, ω-bis[5-amino-phthalazine-1,4 (2H,3H)-dion-]8-yl alkanes [=α, ω-bis(6-luminyl) alkanes]: Investigations on an intramolecular ‘distance effect’

Oligomers of 5-amino-8-vinyl-phthalazine-1,4(2H,3H)-dione exhibit about 0.05% of the chemiluminescence quantum yield of the corresponding ‘monomer unit’, i.e. 5-amino-8-ethyl-phthalazine-1,4(2H,3H)-dione which has a similar quantum yield to luminol. The quantum yields of copolymers of 5-amino-8-vinyl-phthalazine-1,4(2H,3H)-dione (1a) with methyl methacrylate or with styrene increase up to 1000-fold, relative to the quantum yield of oligomers of (1a). Thus the monomer units of methyl methacrylate or styrene appear to act as ‘spacers’ between the lumigenic groups. α,ω-Bis[(5-amino-phthalazine-1,4(2H,3H)-dion-)8-yl] alkanes show an analogue ‘distance’ effect: the chemiluminescence quantum yield increases with increasing alkane chain length. As the fluorescence of the corresponding amino phthalates (which are intermediates in the synthesis of the phthalazine diones) is only slightly influenced by the distance between the lumigenic groups it is suggested that a mainly chemical ‘distance effect’ is working here: the smaller the intramolecular distance between the hydrazide groups the more inhibition exists in respect of the oxidative reaction producing the luminol-type chemiluminescence.     

Simultaneous determination of all-trans-, 13-cis-, 9-cis-retinoic acid and their 4-oxo-metabolites in plasma by high-performance liquid chromatography

A gradient reversed-phase high-performance liquid chromatographic technique is described for the easy separation and quantification of some retinoids; all-trans-retinoic acid, 13-cis-retinoic acid, 9-cis-retinoic acid and their corresponding 4-oxometabolites, in plasma. The method involved a diethyl ether-ethyl acetate (50:50, v/v) mixture extraction at pH 7 with acitretin and 13-cis-acitretin as internal standards. A Nova-Pak C₁₈ steel cartridge column was used. The mobile phase was methanol-acetonitrile (65:35, v/v) and 5% tetrahydrofuran (solvent A) and 2% aqueous acetic acid (solvent B) at 1 ml/min. The gradient composition was (only the percentages of solvent B are mentioned): I, 25% solvent B at the time of injection; II, 12% solvent B at 11 min until 30 min; III, 25% solvent B and maintenance of 25% solvent B for 10 min until a new injection. Total time between injections was 40 min. Detection was by absorbance at 350 nm. The precision calculated for plasma concentrations ranging from 2 to 250 ng/ml was better than 15% and the accuracy was less than 12%. The linearity of the method was in the range of 2 to 400 ng/ml of plasma. The limit of quantification was 2 ng/ml for each of the compounds. The HPLC method was applied to plasma specimens collected from animals receiving single dose administrations of all-trans-retinoic acid, 13-cis-retinoic acid and 9-cis-retinoic acid.     

Investigating the effects of polymer chemistry on activity of biocatalytic plastic materials

The affects of polymer chemistry on the organic solvent activity of alpha-chymotrypsin-containing biocatalytic plastic materials are investigated in this study. To incorporate alpha-chymotrypsin into the polymer, the enzyme is first acryloylated, then solubilized into organic solvents via hydrophobic ion paring with surfactant molecules. Once in the organic solvent, a vinyl monomer and crosslinker are added and copolymerized with the enzyme. Due to the intimate contact between the enzyme and the resulting polymer network, the polymer chemistry plays an important role in the activity of these biocatalytic materials. The chemical composition of the monomer/polymer has the greatest effect on catalytic activity. The activity spans a range of 100-fold and appears to correlate with the hydrophilicity of the monomer, with the lowest activity exhibited for poly(methyl methacrylate) and the highest for poly(2-hydroxyethyl methacrylate). The effect of the chemical structure of the monomer/polymer appears to be an intrinsic kinetic effect, whereas other polymer chemistry conditions investigated, including crosslinker concentration and length and ratio of solvent:monomer during synthesis, appear to effect the rate of substrate diffusion, thereby affecting observed enzyme activity. Changes in the conditions of polymer synthesis can cause as much as a 20-fold change in activity for a given polymeric material. This is most likely due to an increase in the porosity of the materials, and thus a relaxation of diffusional limitations.     

Characterization and evaluation of methyl methacrylate-acetylated Saccharum spontaneum L. graft copolymers prepared under microwave

Hybridization of the natural polymers with synthetic polymers is of great interest because of its application to biomedical and biodegradable materials. Synthesis of graft copolymers of methyl methacrylate (MMA) onto acetylated Saccharum spontaneum L. fiber using ferrous ammonium sulphate–potassium per sulphate (FAS–KPS) redox initiator under the influence of microwave radiation (MWR) was carried-out. Different reaction parameters such as time, initiator molar ratio, monomer concentration, microwave power, pH and solvent were optimized to get maximum graft yield (72.2%). On grafting, percentage crystallinity decreases rapidly with reduction in its stiffness and hardness. The graft copolymers thus formed were characterized by FTIR, SEM, XRD, TGA, DTA and DTG techniques. Moreover, graft copolymers have been found to be more moisture resistant and also showed higher chemical and thermal resistance.     

Bacterial anti-adhesion activity based on the electrochemical properties of polymethacrylates bearing ferrocenyl pendant groups

Abstract

Much current research is focused on preventing and controlling the natural process of colonization by marine organisms of surfaces submerged in seawater. Previously, the authors’ laboratory has reported the synthesis and the full physico-chemical characterization of homopolymers obtained from 1-ferrocenylmethyl methacrylate (FMMA), 2-(ferrocenylmethoxy)ethyl methacrylate (FMOEMA), and 3-(ferrocenylmethoxy)propyl methacrylate (FMOPMA). Here, the bacterial anti-adhesion activity of these homopolymers (pFMMA, pFMOEMA and pFMOPMA) is reported when stimulated in 96-well microplates containing a printed electrochemical cell in each well. Polymers were deposited on the printed carbon working electrode of each well in two columns each comprising eight wells. Their electrochemical anti-adhesion properties were evaluated by inoculating a marine biofilm forming bacterial strain, Pseudoalteramonas lipolytica, in each well and then applying recurrent scans for 15?h. The results revealed an intrinsic anti-adhesion activity of all the polymers. This activity was amplified by a factor of 10 when potential recurrent scans were applied.     

Marine antifouling performance of polymer coatings incorporating zwitterions

Zwitterionic materials display antifouling promise, but their potential in marine anti-biofouling is still largely unexplored. This study evaluates the effectiveness of incorporating small quantities (0–20% on a molar basis) of zwitterions as sulfobetaine methacrylate (SBMA) or carboxybetaine methacrylate (CBMA) into lauryl methacrylate-based coatings whose relatively hydrophobic nature encourages adhesion of the diatom Navicula incerta, a common microfouling organism responsible for the formation of ‘slime’. This approach allows potential enhancements in antifouling afforded by zwitterion incorporation to be easily quantified. The results suggest that the incorporation of CBMA does provide a relatively minor enhancement in fouling-release performance, in contrast to SBMA which does not display any enhancement. Studies with coatings incorporating mixtures of varying ratios of the cationic monomer [2-(methacryloyloxy)ethyl]trimethylammonium chloride and the anionic monomer (3-sulfopropyl)methacrylate, which offer a potentially lower cost approach to the incorporation of anionic and cationic charge, suggest these monomers impart little significant effect on biofouling.     

Luminescence of Eu3+ ions in hybrid polymer‐inorganic composites based on poly(methyl methacrylate) and zirconia nanoparticles

Spherical nanoparticles of ZrO₂ with 2 and 10 mol% EuO_1.5 up to 20 nm size were prepared by the method of hydrothermal synthesis for luminescent functionalization of the polymer–inorganic nanocomposites based on poly(methyl methacrylate). Surface modification of oxide nanoparticles was carried out by 3‐(trimethoxysilyl)propyl methacrylate, dimethoxymethylvinyl silane and 2‐hydroxyethyl methacrylate to provide uniform distribution and to prevent agglomeration of nanosized filler in the polymer matrix. Polymer–inorganic composites were synthesized by in situ free radical polymerization in bulk. Structuring of ZrO₂‐EuO_1.5 nanoparticles in the poly(methyl methacrylate) was studied by very‐small‐angle neutron scattering. According to the results, the dependence of photoluminescent properties of ZrO₂‐EuO_1.5 nanoparticles on the content of lanthanide, the symmetry of the crystal field, surface treatment and the polymer matrix were established. A correlation was shown between Stark splitting in luminescence spectra of ZrO₂‐EuO_1.5 nanoparticles and their phase composition. Using MMT‐assay it was shown that composites based on poly(methyl methacrylate) and ZrO₂‐EuO_1.5 nanoparticles do not have cytotoxic properties, which makes it possible to use them as prosthesis materials with contrasted and luminescent imaging properties.     

Solvent isotope effect on the differences in structure and stability between normal and deuterated proteins

Differential scanning microcalorimetry was used to investigate the enthalpy (ΔH_d) and the temperature (t_d) of thermal denaturation of normal (nondeuterated) (H-PC) and deuterated (D-PC) phycocyanins in D₂O solvent. Values of t_d in D-PC are about 5–7°C lower than those in H-PC. The magnitudes of ΔH_d in D-PC are only 21–32% of those in H-PC. During the protein unfolding, the heat-capacity changes (ΔC_p) in D-PC are also lower than those in H-PC. CD was employed to evaluate the secondary structure and the urea denaturation of these proteins in D₂O solvent. These proteins have about the same α-helix content. D-PC is less resistant to the denaturant urea than is H-PC. In general, the apparent free-energy change in the process of protein unfolding at zero denaturant concentration is higher in H-PC than in D-PC. Comparisons of the present results for D₂O solvent with those previously reported for H₂O reveal that solvent isotope effect essentially does not change the α-helix content in H-PC and D-PC. However, D-PC or H-PC has a higher random-coil content in its secondary structure in D₂O than in H₂O. Substitution of H₂O with D₂O as the solvent increases t_d in both D-PC and H-PC, lowers ΔH_d in H-PC, and greatly lowers ΔH_d in D-PC. The deuterium solvent isotope effect does not change ΔC_p in H-PC but lowers ΔC_p in D-PC. In the urea denaturation, the magnitudes of (C_u)_1/2 in H-PC and D-PC are not affected by such a solvent effect, whereas those of ΔG are greatly increased. These results are correlated with the structure and stability of the proteins.     

Preparation of cholesteric (hydroxypropyl)cellulose/polymer networks and ion-mediated control of their optical properties

(Hydroxypropyl)cellulose (HPC)/vinyl polymer networks were synthesized in film form from liquid-crystalline solutions of HPC in a mixed solvent of methacrylate monomer/methanol/water (2:1:2 in weight) containing cross-linking agents, via photopolymerization of the methacrylate monomer. Di(ethylene glycol) monomethyl ether methacrylate (DEGMEM) or 2-hydroxypropyl methacrylate (HPMA) was used as the polymerizing monomer, and tetra(ethylene glycol) diacrylate and glutaraldehyde were the cross-linkers for the monomers and HPC, respectively. The polymer composite films, HPC/PDEGMEM and HPC/PHPMA, prepared at ca. 60-70 wt % concentrations of HPC in the starting solutions, were iridescently colored due to the selective light reflection, originating from the cholesteric helical arrangement carried over successively into the network system. When the cholesteric films were immersed and swollen in water containing an inorganic neutral salt, their coloration and optical turbidity varied according to a strength of 'chaotropicity' of the impregnant ions. This ionic effect may be interpreted as essentially identical with that found formerly in the coexistent salt-sort dependence of the cholesteric pitch and lower critical solution temperature for HPC aqueous solutions. It is also demonstrated that visual appearance of the swollen networks can be changed by application of an electric potential of practical magnitude between both edges of the samples of rectangular shape.     

Effects of the Reaction Conditions on the Enantio-Selective Esterification Using Candiada Cylindracea Lipase

Parameters influencing the synthetic activity and enantioselectivlty of the Candida cylindracea lipase were investigated. The test reaction was presented through the enantioselective esterification of 2—substituted propionic acids in organic solvents. It was found that both the activity and the enantioselectivity of the lipase could be most effectively influenced by solvent engineering. Since the solvent has a different effect on activity and enantioselectivity of the lipase, selection of the most suitable solvent or solvent mixture is an important optimization question.     

Ultrafast molecular dynamics of biofuel extraction for microalgae and bacteria milking: blocking membrane folding pathways to damaged lipid-bilayer conformations with nanomicelles

Cell milking is a 100% renewable green energy for CO₂ by extraction of biofuels inside the cytosol of photosynthetic micro-organisms as microalgae and bacteria. The cells are exposed to a hydrophobic solvent forming holes and cracks through their membranes from which the biofuels can leak out. In protein folding, the goal would be to find pathways to the unique functional protein conformer. However, in the lipid-bilayer interaction with the solvent for milking, the objective is to block the pathways for damaged membrane conformations of low free energy with undesired nanostructures, using the solvent properties, as shown with an ab initio structural bioinformatic model. Statistical thermodynamics is used to compute the free energy (including entropy) from the molecular dynamics trajectory of the biomolecular system with many conformational changes. This model can be extended to the general problem of biomolecules folding as for proteins and nucleic acids. Using an adaptation of the Einstein diffusion law, the conformational change dynamics of the lipid bilayer depends on the two diffusion coefficients of the solvent: D₁ before the irreversible folding transition time and the much smaller D₂ thereafter. In contrast to the n-hexane and n-heptane hydrocarbons of smaller size, the residual D₂?=?4.7?×?10^?7?cm²/s of the n-decane solvent, with the highest partition coefficient among the three extractors, is the only to present a D₂ value that is significantly below the critical threshold of 10^?6?cm²/s. Therefore, the membrane would resist to long hydrocarbons and the exposed cells would remain viable for milking.