Formation of polyelectrolyte complexes between cellulose derivatives and their blood compatibility

Formation of polyelectrolyte complexes (PECs) between cellulose derivatives in aqueous solution and their blood compatibility were examined. To this end, two types of quaternary ammonium cellulose derivatives, Q-Cell and Q-HEC, were prepared by treating cellulose and hydroxyethyl cellulose (HEC), respectively, with glycidyl trimethylammonium chloride. Anionic derivatives were carboxymethyl cellulose (CMC) with different degrees of substitution (DS) and cellulose sulfate (CS). In vivo blood tests were made by a method of peripheral vein indwelling suture. The results showed that the complex formation of Q-Cell did not follow a stoichiometric reaction, but Q-HEC reacted stoichiometrically with CMC and CS. It was also found that water-insoluble cellulosic PECs are soluble in formic acid, showing that the cellulosic PEC films can be prepared from formic acid solutions. The blood tests revealed that by the criteria of the test method employed in this work, cellulosic PECs had a good blood compatibility.     

Fabrication and properties of antimicrobial cellulose materials based on polyelectrolyte complexes

The effect of the structure of the reacting compounds and reaction conditions on the composition of polyelectrolyte complexes formed in the reaction of polyanions — graft copolymer of cellulose and polyacrylic acid and polymethacrylic acid sodium salt (C-gr-PAa (PMAA)) and polyhexamethyleneguanidine hydrochloride (PHMG) and polyethylenimine (PEI) — and the kinetics of their formation were investigated. The conditions that ensure complete binding of the polycation were determined and the necessity of a significant excess of polycation and long duration of the reaction for formation of complexes of stoichiometric composition was demonstrated. In studying desorption of antimicrobial substances from the polyelectrolyte complex, the effect of the process production scheme and type of cation and the significant role of diffusion factors in this process on the stability of the complex was established. Moscow State Textile Academy. Translated fromKhimicheskie Volokna, No. 3, pp. 14–19, May–June, 1999.     

In vitro blood compatibility of modified PDMS surfaces as superhydrophobic and superhydrophilic materials

The surface of polydimethylsiloxane rubber (PDMS) was irradiated by a CO₂‐pulsed laser. The irradiated surfaces were grafted by hydroxyethylmethacrylate phosphatidylcholine (HEMAPC) by using the preirradiation method. The laser‐treated surfaces and HEMAPC‐grafted PDMS surfaces were characterized by using a variety of techniques including ATR‐FTIR spectroscopy, scanning electron microscopy (SEM), and wettability, which was measured by a water‐drop contact angle. Different surfaces with different wettability were prepared. These surfaces, including untreated PDMS (hydrophobic), laser‐treated PDMS (superhydrophobic), and HEMAPC‐grafted surfaces (superhydrophilic), were used for a platelet adhesion study. Results from in vitro testing indicated that chemical structures, such as negative‐charge polar groups and wettability, are important factors in blood compatibility of these surfaces and the superhydrophilic (the most wettable) and the superhydrophobic (the most unwettable) of modified PDMS surfaces have excellent blood compatibility compared to the unmodified PDMS. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91:2042–2047, 2004     

Study of the stoichiometric polyelectrolyte complex between chitosan and carboxymethyl cellulose

Summary The polyelectrolyte complex (PEC) between chitosan and carboxymethyl cellulose was studied. Turbidimetric measurements revealed that the amount of stoichiometric PEC increased gradually as the solution of one polyelectrolyte was added to the other; the turbidity of the solution reached a maximum for the stoichiometric ratio of the reacting polyelectrolytes in the mixture. At pH 4,0 the composition of the complex is very near to equimolarity. IR spectra and thermal analysis of the PEC exhibited significant differences from those of the 1:1 mixture of the starting polyelectrolytes.     

Swelling of membranes from the polyelectrolyte complex between chitosan and carboxymethyl cellulose

Summary The swelling of membranes of polyelectrolyte complexes formed from chitosan and carboxymethyl cellulose is reported. These membranes adsorb water until a maximum swelling is achieved after which they slowly shrink to an equilibrium value. The maximum swelling value and the time at which it is attained increases as the pH of formation of the complex increases from 4.0 to 5.8. Shrinkage observed at longer times is the result of the segmental mobility of the polyelectrolyte chains in the swollen state which allows the completion of the interpolyelectrolyte reaction. The water uptake up to maximum swelling obeys second order kinetics.     

Preparation of cellulose graft copolymers having polypeptide side chains and their blood compatibility

Blood compatibility of cellulose graft copolymers with poly(γ-benzyl-L -glutamate) and poly(N⁵-2-hydroxyethyl-L -glutamine) (Cell-g-PBLG and Cell-g-PHEG) was examined in vivo blood tests. For this purpose, Cell-g-PBLG graft copolymers with PBLG contents ranging from 7 to 60 mol % were prepared by polymerizing N-carboxy-γ-benzyl-L-glutamate(γ-BLG NCA) using aminoethyl cellulose (AE-Cell) with degree of substitution of 0.05 as macroinitiator. Graft copolymerization was carried out under a variety of conditions at 20°C in dimethyl-sulfoxide. Monomer conversion higher than 60% were obtained for all the polymerization runs. The solubility tests revealed that all of the AE-Cell and the polypeptides formed were grafted. The Cell-g-PHEG graft copolymers were prepared by treating Cell-g-PBLG graft copolymers with 2-amino-1-ethanol. Characterization of these graft copolymers were carried out by IR spectroscopy, DSC, and water content measurement. Tests for blood compatibility, in vivo, were made by a method of peripheral vein indwelling suture which was developed by one of the authors. The coating of graft copolymers on the polyester suture was made by casting either from formic acid solution of LiCl/dimethylacetamide solutions using water as the regenerating medium, and the polymer-coated sutures were implanted into a jugular and femoral vein of a dog. The results showed that the graft copolymers examined have excellent antithrombogenic properties.     

Synthesis, characterization, in vitro and in vivo screening of unsymmetrical borole complexes of 2-hydroxy-N-phenylbenzamide and its derivatives

Biochemical aspects, synthesis and characterization of some boron complexes of 2-hydroxy-N-phenylbenzamide (HOPhBenz) and its semicarbazone (HOPhBenz.SCZH) and thiosemicarbazone (HOPhBenz.TSCZH) are described. These derivatives were prepared by the reactions of 2-isopropoxy-4-methyl-1,3,2-dioxaborolane, and 2-isopropoxy-4-methyl-1,3,2-dioxaborinane with 2-hydroxy-N-phenylbenzamide, 1-[(2-hydroxyphenyl)-1-N-phenylamino]hydrazinecarboxamide (HOPhBenz.SCZH), and 1-[(2-hydroxyphenyl)-1-N-phenylamino]hydrazinecarbothioamide(HOPhBenz.TSCZH) in a 1:1 molar ratio. In order to assess the increase of the inhibitor potency, (HOPhBenz), (HOPhBenz.SCZH), (HOPhBenz.TSCZH) and their boron complexes have been tested in vitro against a number of pathogenic fungi and bacteria at different concentrations and were found to possess remarkable fungicidal and bactericidal properties. The testicular sperm density, testicular sperm morphology, sperm motility, density of cauda epididymal spermatozoa and fertility in mating trials and biochemical parameters of reproductive organs are discussed.     

Diclofenac-hydrotalcite: In vitro and in vivo release experiments

Solutions of the anti-inflammatory drug diclofenac in ethanol and ethanol–water were prepared and mixed with hydrotalcite and hydrotalcite heated at 500 °C. Hydrotalcite pretreated at 500 °C showed a higher adsorption of diclofenac. Diclofenac-hydrotalcites were used for in vitro release experiments to evaluate the percutaneous absorption of diclofenac, using sets of eight Franz cells with membranes of stratum corneum epidermis obtained from human skin; a 2% diclofenac hydroalcoholic gel was used for comparison. Hydrotalcite pretreated at 500 °C is less suitable for release procedures, despite its higher adsorption capacity, whereas diclofenac adsorbed from ethanolic solution by untreated hydrotalcite presents the most efficient sample and shows the best permeation profiles. This sample was selected for the in vivo experiments. Ten healthy volunteers participated on the in vivo experiments: the diclofenac-hydrotalcite appeared to be useful for an efficient application on human skin as inhibitor of the UV-induced erythemas, also better than the usual gel samples.     

Surface modified cellulose nanocrystalline hybrids actualizing efficient and precise delivery of doxorubicin into nucleus with: In vitro and in vivo evaluation

Rod-like-shape nanomedicines with the ability of lysosomal pH-controlled drug release can precisely deliver doxorubicin (DOX) into its target, nucleus, and can fully exert its anticancer effect. Taking advantage of their large specific surface area, cellulose nanocrystals (CNCs) were used to fabricate pH-responsive DOX-loaded rod-like shaped hybrids nanomedicines: cis-aconityl-doxorubicin (CAD)@polyethylenimine (PEI)@CNCs (CAD@PEI@CNCs) via layer-by-layer (LbL) assembly. In vitro, CAD@PEI@CNCs hybrids displayed rod-like shape, high drug loading content, lysosomal pH-controlled drug release, efficient and precise doxorubicin (DOX) delivering into the nucleus. Moreover, the cellular uptake of CAD@PEI@CNCs hybrids was 20.9 folds higher than that of DOX·HCl against A549 cells. The cytotoxicity of CAD@PEI@CNCs hybrids was much higher than that of DOX·HCl and the pH-irresponsive hybrids against A549 cell. In vivo, CAD@PEI@CNCs hybrids exhibited good antitumor effect: (42.0 ± 6)% inhibition rate and few harms to the nude mice. Altogether, rod-like shaped pH-responsive CAD@PEI@CNCs hybrids nanomedicines could efficiently overcome the vascular and tumor barriers, and precisely deliver DOX to nucleus to convert DOX antitumor effects. These results indicate that CAD@PEI@CNCs have great potential to act as advanced nanomedicines with enhanced delivery efficiency and therapeutic efficiency.     

In vitro and in vivo behaviors of dextran functionalized graphene

Development of biocompatible surface coating is critical to engineer various functional nanomaterials for biomedical applications. Here, we present a new surface chemistry of graphene by covalently conjugating graphene oxide (GO) with dextran (DEX), a biocompatible polymer widely used for surface coating of biomaterials. Compared with GO, the graphene–dextran (GO–DEX) conjugate shows reduced sheet sizes, increased thickness and significantly improved stability in physiological solutions. Cellular experiments uncover that DEX coating on GO offers remarkably reduced cell toxicity. We further label GO–DEX with a radioactive isotope, ¹²⁵I, for in vivo tracking in animal studies. It is found that GO–DEX accumulates in the reticuloendothelial system (RES) including liver and spleen after intravenous injection, and importantly, shows obvious clearance from the mouse body within a week without causing noticeable short-term toxicity to the treated animals. Our results suggest that this DEX coating method on GO may potentially be useful to the further development of novel graphene-based bioconjugates for various biomedical applications.     

Interactions between cationic conjugated polyelectrolyte and DNA and a label‐free method for DNA detection based on conjugated polyelectrolyte complexes

The electrostatic complexes of single‐stranded deoxyribonucleic acid (ssDNA) and a cationic conjugated polyelectrolyte (CPE), poly{9,9‐di[3‐(1‐ethyl‐1,1‐dimethyl ammonio)propyl]‐2,7‐fluorenyl‐alt‐1,4‐phenylene dibromide} (PFN), were investigated. Fluorescence emission of PFN solution (10 μmol/L) can be drastically quenched to about one fourth of its original intensity in the presence of a trace amount (2.6 μmol/L) of ssDNA. The effect of oligonucleotide length on the fluorescence quenching behavior was also investigated. In contrast to single‐stranded DNA with 20 bases (ssDNA‐20), ssDNA with 40 bases (ssDNA‐40) induces a relatively higher quenching efficiency and larger red‐shift of PFN emission maximum. The binding constant of ssDNA‐20 and PFN is estimated to be 1.12 × 10²¹. At extremely low concentration (10 nmol/L), PFN can respond to 0.2 nmol/L (or 2 × 10^?10 mol/L) of ssDNA‐20 by significant enhancement of its emission intensity. The result is contrary to the observation in the relative higher concentration, and its mechanism is postulated. Based on the high binding ability of ssDNA with cationic CPE, a label‐free method for ssDNA detection is designed. It uses an electrostatic complex of cationic PFN and an anionic CPE, which exhibits fluorescence resonance energy transfer (FRET) between the two components. Addition of ssDNA improves the FRET extent, indicated by obvious change of fluorescence spectra of the conjugated polyelectrolyte complex. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Dissolution mechanism of polyelectrolyte complexes in aqueous surfactant solutions

The dissolution of polyelectrolyte (PE) complexes (PECs) in cetyl trimethyl–ammonium bromide (CTAB) or in sodium dodecyl sulfate (SDS) has been investigated. It was verified that the complex divides first into its two components (anionic PE and cationic PE) in aqueous surfactant solution; then one of the components reacts with oppositely charged surfactant to produce a PE–surfactant complex. The dissolution property of the PEC mainly depends on the solubility of PE–surfactant, ie the PE–surfactant dissolves in its aqueous surfactant solution, the PEC also dissolves or otherwise it is insoluble. A tentative dissolution mode of PEC in aqueous surfactant solution is proposed. © 2000 Society of Chemical Industry     

In vivo and in vitro lipid accumulation inBorago officinalis L.

Seeds of 13 accessions of borage (Borago officinalis) varied in total fatty acid content from 28.6 to 35.1% seed weight, with linoleic, γ-linolenic, oleic and palmitic as the predominant fatty acids, averaging 38.1%, 22.8%, 16.3% and 11.3% of total fatty acids, respectively. There was an inverse relation between γ-linolenic acid (25.0 to 17.6%) and oleic acid (14.5 to 21.3%). Fatty acid content of leaf tissues was 9.1% dry weight, with α-linolenic acid 55.2% and γ-linolenic acid 4.4% of total fatty acids. Cotyledons were the major source of fatty acids in seeds. Seed fatty acid content increased from <1 mg at six days postanthesis to about seven mg at maturity (22 to 24 days). Individual fatty acid content of seed was relatively constant after day 8. When immature embryos from 6 to 16 days postanthesis were cultured in a liquid or semisolid basal medium, fatty acid composition was similar to that of in vivo-grown seeds. Growth of cultured embryos decreased as sucrose concentration was increased from 3 to 20% in the basal medium, and most embryos did not survive 30% sucrose; fatty acid as a percentage of dry weight was maximal at 6% sucrose.     

Effects of cationic liposome-DNA complexes on pulmonary surfactant function in vitro and in vivo

Cationic liposome-DNA complexes are being evaluated as potential gene therapy agents for the lung. Cations have strong effects on the biophysical functions of lung surfactant. Therefore, we assessed whether cationic liposomes [composed of N-(1-(2,3-dioleyloxy) propyl)-N,N,N-trimethyl-ammonium chloride and dioleylphosphatidylethanolamine] with or without DNA affect behavior of four types of surfactant in vitro. Experiments were carried out using a modified Wilhelmy surface balance. The ability of surfactants that contain protein and anionic lipids to lower surface tension was inhibited in the presence of cationic liposomes. Inactivation was less when DNA was preincubated with cationic liposomes. Surfactant that contained neither protein nor anionic lipids was not inactivated. Mechanical properties of the lung were studied to assess in vivo surfactant function after intratracheal instillation of a cationic liposome-DNA complex into adult rats. Pressure-volume deflation curves were shifted by 18% compared with those from normal (untreated) animals, but this effect was transient and not different from that observed in animals who received a similar volume of saline. These findings indicate that cationic liposomes alone may have deleterious effects on behavior of some surfactants possibly by disrupting charge interactions between negatively charged phospholipids and surfactant proteins. When DNA is added to liposomes before exposure to surfactants, the adverse charge interactions may be obviated by charge neutralization of liposomes by DNA.     

Surface modification by polyelectrolyte complexes: Influence of modification procedure,polyelectrolyte components,and substrates

The complex formation between oppositely charged polyelectrolytes (PEL) and their interaction with negatively charged silicate powders have been investigated. The PEL studied were poly(ethyleneimine)s, poly(diallyldimethylammonium chloride), and copolymers of maleic acid and propylene or styrene. PEL complexes (PEC) are formed by a combination of aqueous PEL solutions containing definite amounts of charges (n₋, polyanion; n₊, polycation). The point of zero charge of the PEC depended on the selection of different PEL. Changing the molar ratio n₋/n₊ permitted the preparation of nonstoichiometric PEC (nPEC). Preformed cationic nPEC were used to modify the silicate powders (variation A). The nPEC were able to generate a strongly cationic surface charge in most cases. It is concluded that the preformed PEC adsorbs roughly with the same stoichiometry on the surface as in solution. Changes of the mechanism and a strong enhancement of the attainable cationic surface charge density could be observed by a two-step modification procedure (variation B). The influence of the surface charge density of the untreated substrates on the extent of surface modification for both variations is also described. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 41–50, 1997     

Preparation and characterization of polyvinyl alcohol based biomaterials: Water sorption and in vitro blood compatibility study

Semi‐interpenetrating polymer networks (semi‐IPNs) based on polyvinyl alcohol (PVA) and crosslinked polyacrylamide (PAM) were prepared by redox polymerization and further characterized by FTIR, ESEM, and XRD techniques. The semi‐IPNs of varying compositions were investigated for their water sorption behavior, and the network parameters like average molecular weight between crosslinks (M_C) and crosslink density were evaluated from water imbibition measurements. The semi‐IPNs were also judged for their in vitro blood compatibility by blood clot formation and percent hemolysis test. It was noticed that the chemical architecture exert a profound effect on the over all performance of the biomaterials. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2402–2408, 2006     

In vitro enzymatic degradation kinetics of polymeric blends of crosslinked starch and carboxymethyl cellulose

Hydrophilic blend matrices of crosslinked starch and carboxymethyl cellulose were synthesized and their susceptibilities to enzymatic degradation were assessed by taking α‐amylase as a model enzyme. The polymeric blends were characterized by FT‐IR spectroscopy, differential scanning calorimetry and scanning electron microscopy. The influence of the chemical compositions of the blends, and the pH values and temperatures of the α‐amylase solutions was investigated by studying the swelling and degradation kinetics of the blends. The impact of the concentrations of the enzyme solutions on the degradation profiles was also examined. The blends were found to exhibit a mixed type of degradation mechanism, ie both diffusion and surface erosion. Copyright © 2005 Society of Chemical Industry     

Liquid-crystalline state of cellulose and its derivatives

Conclusions Literature material on the liquid-crystalline state of solutions and melts of cellulose and its derivatives has been analyzed.Translated from Khimicheskie Volokna, No. 3, pp. 8–12, May–June, 1983.     

Rheological properties of an interpolymer complex formed between poly(acrylic acid) and methyl cellulose

Some rheological properties of an interpolymer complex formed in the mixtures of aqueous solutions of poly(acrylic acid) and methyl cellulose are investigated. In a diluted state, the complex exhibits polyelectrolyte properties, and in the shear field, it flows like a pure poly(acrylic acid) solution. From the experimental data obtained from the mixture flow in a longitudinal field, an effective relaxation time was calculated. It turned out to be higher than that for the initial components. The deviation of the experimental values of the viscosity from the calculated additive ones allowed us to determine the critical molecular weight of the poly(acrylic acid) below which the complex is not formed: M_cr ≈ 6 × 10⁴, which is one order of magnitude higher than for the mixtures of spatially complementary macromolecules. The increase of the total polymer concentration in the mixture first leads to an increase of the complex size. Further increase of the polymer concentration and transition to the semidiluted state decreases the complex size and also decreases its solubility in water. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 1523–1528, 1999     

In vitro and in vivo Digestibility of Blended and Corresponding Interesterified Fats in Rats

The process of interesterification of fat blends namely vanaspati-ground-nut oil (40:60) (vanaspati-GNO), sal fat and groundnut oil (30:70) (sal-GNO), sheep tallow and groundnut oil (30:70) (ST-GNO), and cottonseed oil (CSO) was found to bring about limited but consistent increase in in vitro digestibility (compared to starting stocks) during first four hours studied. Apparent digestibility of blends of sal-GNO and vanaspati-GNO in rats was not effected by the process of interesterification while interesterified products had significantly higher in vivo true digestibility compared to starting stocks.