New scheme for electrochemical detection of DNA based on electrocatalytic oxidation of NADH

A new electrocatalytic scheme for the detection of DNA is described. This scheme relies on the different interactions of single- and double-stranded oligonucleotides with the organic dyes methylene blue, thionin, azure A, azure B, toluidine blue O, brilliant cresyl blue and neutral red, which in addition can act as NADH catalysts. This catalytic activity can be used for amplifying differentiation between duplex and single-stranded DNA. Pyrolytic graphite electrodes modified with adsorbed dsDNA–organic dye complexes gave higher electrocatalytic NADH oxidation currents than those measured with electrodes modified with adsorbed ssDNA–organic dye. This difference is maximum for brilliant cresyl blue. These results suggest that the proposed scheme may be useful for the detection of DNA hybridisation and damage.     

Polymerization under a magnetic field. VI. Triplet dye-sensitized photopolymerization of acrylamide and methyl methacrylate

Methylene blue sensitized photopolymerization of acrylamide (AM) and methyl methacrylate (MMA) using triethanolamine or the sodium salt of EDTA as a reducing agent has been investigated under the influence of a magnetic field (0–7.3 kG). There was no effect of the magnetic field (MF) on the polymerization of AM and MMA in aqueous medium. However, in the water–methanol mixture (1 : 1) the yield of polymer decreases and the molecular weight increases in both cases under MF. This has been explained on the basis of the triplet mechanism. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1509–1513, 1998     

Synthesis,characterization, and molecular recognition of sugar‐functionalized nanoparticles prepared by a combination of ROP,ATRP, and click chemistry

The aim of this work was to prepare nanoparticles bearing sugar residues at their surface through the synthesis of amphiphilic block copolymer of poly d,l‐lactide (PLA) and poly(ethylene glycol)methacrylate, with the hydrophilic part terminating with glucopyranoside molecules as a model for any carbohydrate ligand. The construction was achieved by a combination of click chemistry, ring‐opening polymerization, and atom transfer radical polymerization. The modified monomer and resulting copolymer were characterized by NMR, SEC, and FTIR. Nanoparticles with a mean hydrodynamic diameter of <200 nm as determined by quasi‐elastic light scattering were prepared from the amphiphilic copolymer by nanoprecipitation using dimethylformamide (DMF) as water‐miscible solvent. In the range of 2.5–10 mg copolymer/mL DMF, the polymer concentration did not have much effect on the size of the nanoparticles. Accessibility of glucopyranoside molecules on the surface of the nanoparticles was confirmed by formation of aggregates from nanoparticles in the presence of concanavalin A observed by transmission electronic microscopy. Finally, no significant cytotoxicity toward human umbilical vein endothelial cells was detected for the final nanoparticles. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3178–3187, 2010     

Electrochemical preparation of composite of poly brilliant cresyl blue (PBCB)–poly 5-amino-2-napthalenesulfonic acid electrode and electrocatalytic application

Poly brilliant cresyl blue (PBCB) and poly 5-amino-2-napthalenesulfonic (PANS) polymer composite modified electrode was fabricated by the electrochemical polymerization of brilliant cresyl blue and 5-amino-2-napthalenesulfonic acid. When compared polymer composite electrodes with PBCB and PANS electrode, it showed enhanced electrochemical property. The morphology of the resulting composite electrode was characterized by AFM, and the electrochemical properties of the modified electrode were characterized by cyclic voltammetry and amperometry. The composite electrode showed surface-confined and pH-dependent electrochemical property. The composite electrode exhibited high catalytic behavior toward the reduction of hydrogen peroxide at low overpotential. The detection limit and sensitivity of the electrode toward H₂O₂ detection was 5 μM and 1 μA/mM, respectively, and response time was less than 10 s for hydrogen peroxide.     

A simple method for the anionic polymerization of α-carbonyl acids in water

Anionic polymerization of α-carbonyl acids such as ketomalonic acid, glyoxylic acid, and pyruvic acid, via carbonyl group to form the corresponding polyether in basic aqueous media, was presented. Cogeneration of carbonyl form of monomer and the carbanion of tartronic acid disodium salt was essential for the anionic polymerization. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 189–193, 1998     

Kinetic investigations on the photopolymerization of di- and tetrafunctional (meth)acrylic monomers in polymeric matrices. ESR and calorimetric studies. I. Reactions under irradiation

The photopolymerization of several di- and tetrafunctional (meth)acrylic monomers in the presence of a styrene–butadiene–styrene polymeric matrix (SBS) has been studied. Electron spin resonance spectroscopy (ESR) and differential scanning photocalorimetry (photo-DSC) were used as monitoring techniques to identify the photogenerated radicals and analyze photopolymerization profiles, radical environments, and radical secondary reactions. The study of the photopolymerization and/or photocrosslinking reactions of these monomers in the solid media was carried out by taking into consideration different factors, such as the influence of both monomer and photoinitiator structures on the hydrogen abstraction in the binder with formation of benzylic and allylic radicals, the polymerization of the monomers itself and the hydrogen abstraction reaction in the polymerized acrylic chains. Finally, irradiation of the system SBS/photoinitiator in the absence of monomer was also accomplished. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2775–2783, 1998     

RAFT made methacrylate copolymers for reversible pH‐responsive nanoparticles

In this study, we designed and investigated pH‐responsive nanoparticles based on different ratios of monomers with primary, secondary or tertiary amino groups. For this purpose, copolymers of methyl methacrylate (MMA) with different compositions of amino methacrylates (2‐(dimethylamino)ethyl methacrylate (DMAEMA), 2‐(tert‐butylamino)ethyl methacrylate (tBAEMA) and 2‐aminoethyl methacrylate hydrochloride (AEMA·HCI)) were synthesized using the reversible addition‐fragmentation chain transfer (RAFT) polymerization process. The controlled nature of the radical polymerization was demonstrated by kinetic studies. All copolymers show low dispersities (?_M < 1.2) with amino contents between 9 and 21 mol %. For the nanoparticle formation, nanoprecipitation with subsequent solvent evaporation was used. All suspensions were characterized by dynamic light scattering (DLS) and scanning electron microscopy (SEM). Different initial conditions of the formulations resulted in differently sized nanoparticles that have monomodal size distributions, relatively narrow polydispersity index (PDI) values and positive zeta potential values. The pH‐stability test results demonstrated that, depending on the structure and amount of the amino content, the obtained nanoparticles reveal a reversible pH‐response, such as dissolution at acidic pH values. The ability of the nanoparticles to encapsulate guest molecules was confirmed by pyrene fluorescence studies. The cytotoxicity assay results showed that the nanoparticles did not have any significant cytotoxic effect. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 2711–2721     

Kinetics and mechanisms of emulsion polymerization of vinylidene chloride. I. Effects of operating variables on the rate of polymerization and the number of polymer particles produced

Emulsion polymerization of vinylidene chloride was carried out at 50°C using sodium lauryl sulfate as emulsifier and potassium persulfate as initiator, respectively. Contrary to the results so far reported, the stirring rate did not affect the progress of the polymerization and such an abnormal kinetic behavior as the rate of polymerization suddenly drops in the course of polymerization was not observed. The number of polymer particles produced was proportional to the 0.7 power of the concentration of emulsifier forming micelles and to the 0.3 power of the initial initiator concentration, respectively, and was independent of the initial monomer concentration. The rate of polymerization was in proportion to the 0.3 power of the concentration of emulsifier forming micelles, to the 0.5 power of the initial initiator concentration, to the 0.2 power of the initial monomer concentration, and to the 0.45 power of the number of polymer particles, respectively. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1919–1928, 1998     

聚灿烂甲酚蓝修饰玻碳电极的制备及电化学性质

在含灿烂甲酚蓝的磷酸缓冲溶液中,用循环伏安法扫描.在经预处理的玻碳电极上形成了聚合物薄膜.在-0.7V-+0.9V(vsSCE)的扫描电位范围和弱碱性介质中形成的薄膜具有较高电活性和稳定性.制备好的聚灿烂甲酚蓝修饰电极在磷酸缓冲溶液的循环伏安曲线有两对氧化还原峰,峰电位随pH升高而向负电位方向移动.该电极对NADH的电化学氧化有催化作用,使其氧化电位负移了270mV并增大了氧化峰电流.     

Potentiometric determination of the stability constants of the fluoroborate-dye complexes used in colorimetric analysis for boron

An extensive bibliography on the determination of boron by means of tetrafluoroborate-dye complexes is given. The stability constants of the fluoroborate—dye complexes are calculated from potentiometric measurements with an Orion fluoroborate ion-selective electrode, for the following nineteen dyes: methylene blue, methylene green, new methylene blue N, thionine, toluidine blue O, malachite green, brilliant green, crystal violet, fuchsine, methyl green, methyl violet, Victoria blue B, brilliant cresyl blue, Nile blue A, rhodamine B, rhodamine 6G, pyronine Y, safranine T and Janus green B. The solubilities of these dyes have been determined by spectrophotometry.     

Polymerization of propylene by metallocene and Ziegler–Natta mixed catalytic systems. Study of polypropylene properties

Propylene was polymerized with metallocene and Ziegler–Natta mixed-catalytic systems to obtain reactor blends of metallocene and Ziegler–Natta-derived propylene homopolymers. The two catalytic systems are able to act jointly, providing individual polymers with different melting and crystallization temperatures. Compatibility between the components of the mixed-catalytic systems and the influence of the components on the polymerization process and on the properties of the reactor blends were studied. Thermal, mechanical, viscoelastic, rheological, and optical properties of the blends were tested and compared with those of conventional polypropylene grades. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 3063–3072, 1998     

Generation of core/shell iron oxide magnetic nanoparticles with polystyrene brushes by atom transfer radical polymerization

The functionalization of nanoparticle surfaces is required to improve the dispersion of an inorganic material inside an organic matrix. In this work, polystyrene (PS) brushes were grown on the surface of iron oxide magnetic nanoparticles with atom transfer radical polymerization and a grafting‐from approach. After polymerization, the magnetic nanoparticles had a graft density of 0.9 PS chains/nm². A sacrificial initiator was used to obtain a satisfactory result for the control of the polymerization, as its addition had to generate a sufficient concentration of persistent radicals (deactivator). A variety of techniques, such as Fourier transform infrared spectroscopy, thermogravimetric analysis, gel permeation chromatography, water contact‐angle measurements, and atomic force microscopy, were used to characterize the nanoparticles. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4744–4750, 2007     

Seeded microemulsion polymerization of butyl acrylate

The seeded microemulsion polymerization of butyl acrylate was studied with γ-rays. The hydrodynamic diameter and its distribution of polymer particles in the seeded microemulsion before and after polymerization were determined with photon correlation spectroscopy (PCS). Though there were micelles in the microemulsion, it was found that new particle formation could be ignored during polymerization. The polymerization kinetics of the seeded microemulsion was investigated. The polymerization rate increases with the dose rate and added monomer content and decreases with the seed fraction. It was completely different from that for seeded emulsion polymerization. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2631–2635, 1998     

Synthesis of ordered polymer by direct polycondensation. VIII. Ordered polymer from two nonsymmetric monomers

The ordered (-aacdbbdc-) polymer was prepared by the direct polycondensation of a pair of symmetric monomers (XabX), 4,4′-(oxydi-p-phenylene)dibutanoic acid (XaaX) and 2-methoxyisophthalic acid (XbbX), with a nonsymmetric monomer (YcdY), 4-aminobenzhydrazide, using the condensing agent diphenyl (2,3-dihydro-2-thioxo-3-benzoxazolyl)phosphonate ( 1 ). The polymerization was carried out by a one-pot procedure, that is, mixing the dicarboxylic acids, condensing agent 1 and triethylamine in NMP for 2 h at room temperature, followed by the addition of 4-aminobenzhydrazide. This polymerization proceeded smoothly, yielding the ordered polymer with an inherent viscosity of 0.34 dL g⁻¹. The microstructure of the ordered polymer was confirmed by comparing the authentic ordered polymer in their ¹³C-NMR spectrum. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2309–2314, 1998     

Polycyclic phosphonate resins: Thermally cross-linkable intermediates for flame-retardant materials

Two series of polycyclic phosphonates were synthesized by reacting p-substituted phenol–formaldehyde resins with excess phosphonic dichlorides under dilute conditions in a polar aprotic solvent. MALDI–TOF was used to detect the absolute masses of different species formed under these conditions. The presence of phosphorus-containing species was also confirmed by ³¹P-NMR. The polycyclics were subjected to ring-opening polymerization simultaneously with a transesterification reaction with commercial polycarbonates in order to cross-link the polymers and to impart flame retardancy to the final thermosetting materials. Thermal properties of the polycarbonates containing phosphonate moieties were determined by thermogravimetric analysis and differential scanning calorimetry techniques. Percent char yields of the final thermosetting materials were considerably higher than that of the linear polycarbonates. Polycyclic phosphonates, therefore, can potentially be used to impart flame retardance to polymers. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1911–1918, 1998     

Flow injection catalytic determination of ruthenium with spectrophotometric detection

A new flow injection catalytic method was described for the determination of ruthenium(III) based on its catalytic effect on the oxidation of brilliant cresyl blue (BCB) by periodate in acidic media. The reaction was followed spectrophotometrically by measuring the absorbance of the dye at 635 nm. Under optimum conditions, ruthenium can be determined in the range of 1.0-100.0 ng ml(-1) with a relative standard deviation of 1.1% and with a limit of detection of 0.70 ng ml(-1). The influence of reagent and manifold variables were studied and optimized. The method was tested for the determination of ruthenium(III) in some synthetic mixtures.     

Hyperbranched polyphosphoesters with reactive end groups synthesized via acyclic diene metathesis polymerization and their transformation to crosslinked nanoparticles

A novel hyperbranched polyphosphoester (HBPPE) was prepared by acyclic diene metathesis (ADMET) polymerization of an AB₂ monomer using the second‐generation Hoveyda–Grubbs catalyst. IR analysis, gel permeation chromatography with multiangle laser light scattering, and NMR spectroscopy confirmed their controlled synthesis. The effect of the ADMET polymerization time in the thermal properties of HBPPEs was studied and their thermal degradation and flame‐retardant properties were evaluated. These reactive HBPPEs were used to synthesize polyphosphoesters nanoparticles by intramolecular crosslinking of the end acrylate groups in dilute solution. The successful preparation of this new type of polymer nanoparticles was proven by NMR spectroscopy and gel permeation chromatography. The morphologies of nanostructures were investigated via dynamic light scattering, atom force microscopy, and transmission electron microscopy. The results revealed that the crosslinked nanoparticles, which have a comparatively uniform size, were stable and reproducible in organic solvents. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 4331–4340     

Graft polymerization of vinyl monomers inside macroporous polyacrylamide gel,cryogel, in aqueous and aqueous‐organic media initiated by diperiodatocuprate(III) complexes

Graft polymerization initiated by diperiodatocuprate(III) complex (Cu(III)) initiator was found to be an effective and convenient method for graft polymerization of vinyl monomers onto macroporous polyacrylamide gels, the so‐called cryogels (pAAm‐cryogels). The effect of time, temperature, monomer and initiator concentration during the graft polymerization in aqueous and aqueous‐organic media was studied. The graft polymerization of water‐soluble monomers as [2‐(methacryloyloxy)ethyl]‐trimethylammonium chloride, 2‐hydroxyethyl methacrylate, N‐isopropylacrylamide, and N,N‐dimethylacrylamide proceeds with higher grafting yield in aqueous medium, as compared with that in aqueous‐organic media. Graft polymerization in aqueous‐organic media such as water–DMSO solutions allows grafting of water‐insoluble monomers such as glycidyl methacrylate and N‐tert‐butylacrylamide with high grafting degrees of 100 and 410%, respectively. It was found that the deposition of initiator on the pore surface of cryogels promoted graft polymerization by facilitating the formation of the redox couple Cu(III)‐acrylamide group. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1952–1963, 2006     

Synthesis of well‐defined polymer brushes on the surface of zinc antimonate nanoparticles through surface‐initiated atom transfer radical polymerization

Zinc antimonate nanoparticles consisting of antimony and zinc oxide were surface modified in a methanol solvent medium using triethoxysilane‐based atom transfer radical polymerization (ATRP) initiating group (i.e.,) 6‐(2‐bromo‐2‐methyl) propionyloxy hexyl triethoxysilane. Successful grafting of ATRP initiator on the surface of nanoparticles was confirmed by thermogravimetric analysis that shows a significant weight loss at around 250–410 °C. Grafting of ATRP initiator onto the surface was further corroborated using Fourier transform Infrared spectroscopy (FT‐IR) and X‐ray photoelectron spectroscopy (XPS). The surface‐initiated ATRP of methyl methacrylate (MMA) mediated by a copper complex was carried out with the initiator‐fixed zinc antimonate nanoparticles in the presence of a sacrificial (free) initiator. The polymerization was preceded in a living manner in all examined cases; producing nanoparticles coated with well defined poly(methyl methacrylate) (PMMA) brushes with molecular weight in the range of 35–48K. Furthermore, PMMA‐grafted zinc antimonate nanoparticles were characterized using Thermogravimetric analysis (TGA) that exhibit significant weight loss in the temperature range of 300–410 °C confirming the formation of polymer brushes on the surface with the graft density as high as 0.26–0.27 chains/nm². The improvement in the dispersibility of PMMA‐grafted zinc antimonate nanoparticles was verified using ultraviolet‐visible spectroscopy and transmission electron microscopy. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010