Periodontitis is a common global disease caused by bacterial dysbiosis leading to tissue destruction, and it is strongly associated with anaerobic bacterial colonization. Therapeutic strategies such as oxygen therapy have been developed to positively influence the dysbiotic microbiota, and the use of oxygen-releasing substances may offer an added benefit of avoiding systemic effects commonly associated with antibiotics taken orally or hyperbaric oxygen therapy. Therefore, the oxygen release of calcium peroxide (CaO2) was measured using a dissolved oxygen meter, and CaO2 solutions were prepared by dissolving autoclaved CaO2 in sterile filtered and deionized water. The effects of CaO2 on planktonic bacterial growth and metabolic activity, as well as on biofilms of Streptococcus oralis and Porphyromonas gingivalis, were investigated through experiments conducted under anaerobic conditions. The objective of this study was to investigate the potential of CaO2 as an antimicrobial agent for the treatment of periodontitis. Results showed that CaO2 selectively inhibited the growth and viability of P. gingivalis (p < 0.001) but had little effect on S. oralis (p < 0.01), indicating that CaO2 has the potential to selectively affect both planktonic bacteria and mono-species biofilms of P. gingivalis. The results of this study suggest that CaO2 could be a promising antimicrobial agent with selective activity for the treatment of periodontitis.

Periodontitis is a chronic biofilm-associated inflammatory disease of the tooth-supporting tissues that causes tooth loss. It is strongly associated with anaerobic bacterial colonization and represents a substantial global health burden. Due to a local hypoxic environment, tissue regeneration is impaired. Oxygen therapy has shown promising results as a potential treatment of periodontitis, but so far, local oxygen delivery remains a key technical challenge. An oxygen (O-2)-releasing hyaluronic acid (HA)-based dispersion with a controlled oxygen delivery was developed. Cell viability of primary human fibroblasts, osteoblasts, and HUVECs was demonstrated, and biocompatibility was tested using a chorioallantoic membrane assay (CAM assay). Suppression of anaerobic growth of Porphyromonas gingivalis was shown using the broth microdilution assay. In vitro assays showed that the O-2-releasing HA was not cytotoxic towards human primary fibroblasts, osteoblasts, and HUVECs. In vivo, angiogenesis was enhanced in a CAM assay, although not to a statistically significant degree. Growth of P. gingivalis was inhibited by CaO2 concentrations higher than 256 mg/L. Taken together, the results of this study demonstrate the biocompatibility and selective antimicrobial activity against P. gingivalis for the developed O-2-releasing HA-based dispersion and the potential of O-2-releasing biomaterials for periodontal tissue regeneration.

The biocompatibility of carrier nanomaterials in blood is largely hampered by their activating or inhibiting role on the clotting system, which in many cases prevents safe intravascular application. Here, we characterized an aqueous colloidal ethyl hydroxyethyl cellulose (EHEC) solution and tested its effect on ex vivo clot formation, platelet aggregation, and activation by thromboelastometry, aggregometry, and flow cytometry. We compared the impact of EHEC solution on platelet aggregation with biocompatible materials used in transfusion medicine (the plasma expanders gelatin polysuccinate and hydroxyethyl starch). We demonstrate that the EHEC solution, in contrast to commercial products exhibiting Newtonian flow behavior, resembles the shear-thinning behavior of human blood. Similar to established nanomaterials that are considered biocompatible when added to blood, the EHEC exposure of resting platelets in platelet-rich plasma does not enhance tissue thromboplastin- or ellagic acid-induced blood clotting, or platelet aggregation or activation, as measured by integrin αIIbβ3 activation and P-selectin exposure. Furthermore, the addition of EHEC solution to adenosine diphosphate (ADP)-stimulated platelet-rich plasma does not affect the platelet aggregation induced by this agonist. Overall, our results suggest that EHEC may be suitable as a biocompatible carrier material in blood circulation and for applications in flow-dependent diagnostics.

The thermodynamic behavior of the system H2O/BSA was studied at 25 °C within the entire composition range: vapor pressure measurements via head space sampling gas chromatography demonstrate that the attainment of equilibria takes more than one week. A miscibility gap was detected via turbidity and the coexisting phases were analyzed. At 6 °C the two phase region extends from ca. 34 to 40 wt % BSA; it shrinks upon heating. The polymer rich phase is locally ordered, as can be seen under the optical microscope using crossed polarizers. The Flory-Huggins theory turns out to be inappropriate for the modeling of experimental results. A phenomenological expression is employed which uses three adjustable parameters and describes the vapor pressures quantitatively; it also forecasts the existence of a miscibility gap.

In contrast to all earlier work on that subject, measurements are performed at high dilution up to total polymer concentrations wpol of 0.5 wt%. Aqueous solutions of poly(2-vinylpyridinium-Br) and of poly(styrene sulfonate-Na) are only fully miscible if wpol < 0.02 wt%. Decomposition into two liquid phases is observed upon an increase in wpol, where the extension of the miscibility gap is considerably larger at 60 than at 25 degrees C. Viscosity measurements demonstrate that the formation of the polyelectrolyte complexes may take hours. The intrinsic viscosity of the polyanion turns out to be 20 times larger than that of the polycation and to be much more sensitive toward the addition of extra salt. The [?] values of the blend pass a minimum as a function of its composition.

The interaction of linear and of three-arm star polybutadiene (PB) with THF was studied in the temperature range between 25 and 55 degrees C. Information for dilute solution rests on light scattering experiments; Flory-Huggins interaction parameter chi stem from vapor pressure measurements as a function of phi, the volume fraction of polymer. Despite the minute divergence in the architecture, the second osmotic virial coefficients of the two PBs differ noticeably. The present work demonstrates that these disparities become much more pronounced as phi increases and that they depend strongly on temperature. These findings are interpreted on the basis of an approach accounting for the effects of chain connectivity and for conformational changes of the components. In this manner it is possible to rationalize the observed complex dependencies chi (phi, T), and to relate these effects to the dissimilar free volumes of the polymers.

A reliable method to decide whether two polymers A and B are miscible or incompatible would be very helpful in many ways. In this contribution we demonstrate why traditional procedures cannot work. We propose to use the intrinsic viscosities [ η ] of the polymer blends instead of the composition dependence of the viscosities as a criterion for polymer miscibility. Two macromolecules A and B are miscible because of sufficiently favorable interactions between the two types of polymer segments. For solutions of these polymers in a joint solvent, this Gibbs energetic preference of dissimilar intersegmental contacts should prevail upon dilution and lead to the formation of interpolymer complexes, manifesting themselves in deviations from the additivity of intrinsic viscosities.

Joint aqueous solutions of branched dextran and linear pullulan are investigated with respect to their phase separation. The experiments demonstrate that the polymers are depending on the molar mass of dextran incompatible in aqueous solutions despite their chemical similarity. This finding can be modeled on the basis of an approach accounting for chain connectivity and conformational relaxation of the components. According to these calculations, the polymers exhibit a miscibility gap in joint solutions despite the favorable interactions between them. Using information on the subsystems H2O/dextran and H2O/pullulan, the assumption of complete miscibility of the polysaccharides is required to model the observed phase separation. This analysis predicts the existence of two islands of immiscibility for the ternary system.

The intrinsic viscosities, [eta], of nine cellulose samples, with molar masses from 50 x 10(3) to 1 390 x 10(3) were determined in the solvents NMMO*H(2)O (N-methyl morpholin N-oxide hydrate) at 80 degrees C and in cuen (copper II-ethlenediamine) at 25 degrees C. The evaluation of these results with respect to the Kuhn-Mark-Houwink relations shows that the data for NMMO*H(2)O fall on the usual straight line in the double logarithmic plots only for M <= 158 10(3); the corresponding [eta]/M relation reads log ([g]/mL g(-1)) = -1.465 + 0.735 log M. Beyond that molar mass [eta] remains almost constant up to M approximate to 10(6) and increases again thereafter. In contrast to NMMO*H(2)O the cellulose solutions in cuen behave normal and the Kuhn-Mark-Houwink relation reads log ([eta]/mL g(-1)) = -1.185 + 0.735 log M. Possible reasons for the dissimilarities of the behavior of cellulose in these two solvents are being discussed. The comparison of three different methods for the determination of [eta] from viscosity measurements at different polymer concentrations, c, demonstrates the advantages of plotting the natural logarithm of the relative viscosities as a function of c. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 119: 670-676, 2011

Dextran and random dextran-based copolymers containing different molar fractions f of charged units are studied in aqueous solution and in the pure state. The specific volumes of the solutions decrease linearly with increasing weight fraction of the polymer. Extrapolation to the pure state yields information on the hypothetical liquid polymers, exhibiting a pronounced minimum at f approximate to 0.1. A similar dependence is also observed for the pure solid polymers; however, the specific volumes at low f are considerably larger and at high f are slightly smaller. These differences are discussed in terms of the non-equilibrium structures formed during sample preparation. The thermal expansivities of the solutions pass through a maximum at f approximate to 0.1. Light scattering shows that the thermodynamic quality of water has a minimum at f approximate to 0.1.

The Flory-Huggins interaction parameter chi is determined as a function of volume fraction of polymer phi by vapor-pressure measurements at 25, 37.5 and 50 degrees C for five dextran samples that differ in f, the fraction of randomly distributed charged monomer units. The function chi(phi) has a minimum that is shifted towards lower chi values as f increases. The higher the temperature, the more the individual curves fan out. The heats of dilution at high polymer concentrations change from exothermal to endothermal as f increases. The results can be well modeled by an approach accounting explicitly for chain connectivity and conformational changes. A smooth transition of the solution properties upon the random introduction of charged units into dextran is observed.

The vapor pressure of water was measured for binary mixtures with cellulose containing fabrics at 37 °C by means of two complementary methods. Different types of fabrics were studied: One consisting exclusively of cellulose fibers, either of natural origin (cotton) or regenerated from solutions in the mixed solvent NMMO/water (Lyocell fibers, CLY) and another kind of fabric containing polyethylene terephthalate (PET) fibers in addition to CLY fibers. The Flory-Huggins interaction parameters χ and their composition dependence calculated from these vapor pressure data are broadly similar for cotton and for CLY, apart from the fact that water interacts somewhat more favorably with CLY than with cotton. In both cases the χ values pass successively a maximum and a minimum as the concentration of water rises. The experiments performed with the fabrics containing two types of fibers demonstrate that the water uptake of PET is negligible as compared with that of cellulose. The results for the system water/cellulose fibers obtained at 37 °C differ fundamentally from corresponding data for 80 °C, reported for cellulose films prepared from solutions in dimethylacetamide + LiCl. The maximum water uptake of cellulose is determined by its degree of crystallinity. In all cases it is possible to model the Flory-Huggins interaction parameters as a function of composition quantitatively by means of an approach subdividing the dilution process conceptually into two separate steps: Contact formation between the dissimilar components (keeping their conformation constant) and subsequent relaxation of the system into the equilibrium state. Similarities and dissimilarities of the systems water/polysaccharide are being discussed in detail.

The thermodynamic behavior of linear and of branched oligo(dimethylsiloxane) (O-DMS) solutions was studied by means of vapor pressure measurements and vapor pressure osmometry at different temperatures for the thermodynamically favorable solvent THF. The branched material required for that purpose was synthesized and afterwards fractionated by means of the single solvent acetone to eliminate components of low degrees of branching. The Flory-Huggins interaction parameters, chi, for the systems THF/O-DMS as a function of composition pass a minimum at all temperatures (25, 40, and 60 degrees C) in the case of the branched material. For the unbranched oligomer such a minimum is only observed at 60 degrees C. At 40 degrees C the results are ambigous whereas the dependence is definitely linear at 25 degrees C. This exceptional behavior of the linear product at the latter temperature is tentatively attributed to the formation of favorable orientational order in the pure state under these conditions. At high oligomer concentrations THF interacts more favorably with the branched material, however, this preference is reversed upon dilution. All measured composition dependencies of chi can be modeled quantitatively by an approach accounting for chain connectivity and for the ability of the oligomers to change their conformation upon dilution. (C) 2010 Wiley Periodicals, Inc. J Polym Sc) Part B: Polym Phys 48: 1309-1318, 2010

ABSTRACT During vinification microbial activities can spoil wine quality. As the wine-related lactic acid bacterium Pediococcus parvulus is able to produce slimes consisting of a β-1,3-glucan, must and wine filtration can be difficult or impossible. In addition, the metabolic activities of several wild-type yeasts can also negatively affect wine quality. Therefore, there is a need for measures to degrade the exopolysaccharide from Pediococcus parvulus and to inhibit the growth of certain yeasts. We examined an extracellular β-1,3-glucanase from Delftia tsuruhatensis strain MV01 with regard to its ability to hydrolyze both polymers, the β-1,3-glucan from Pediococcus and that from yeast cell walls. The 29-kDa glycolytic enzyme was purified to homogeneity. It exhibited an optimal activity at 50°C and pH 4.0. The sequencing of the N terminus revealed significant similarities to β-1,3-glucanases from different bacteria. In addition, the investigations indicated that this hydrolytic enzyme is still active under wine-relevant parameters such as elevated ethanol, sulfite, and phenol concentrations as well as at low pH values. Therefore, the characterized enzyme seems to be a useful tool to prevent slime production and undesirable yeast growth during vinification.

The efficiencies of two large-scale fractionation techniques namely continuous polymer fractionation (CPF) and continuous spin fractionation (CSF) are compared. To this end, we used a commercially available sample of poly(vinyl methyl ether). Both methods are suitable to reduce the nonuniformity of the sample below 0.6. The results demonstrate that CSF has a better fractionation performance than the progenitor method, CPF. A further advantage is the three times higher throughput of CSF.

The interaction of butadiene-styrene block copolyincis of different molecular architecture with tetrahydrofuran (THF) was studied by vapor pressure and light scattering experiments in the temperature range from 25 to 55 degrees C The thus obtained Flory-Huggins interaction parameters, chi, as a function of phi, the volume fraction of the polymers, were compared with that of the corresponding homopolymersim in the same solvent The results are very similar for all block copolymers (diblock, triblock and star-shaped, butadlene In the chi(phi) Curves of the homopolymers, which are always located center) and for all temperatures In contrast to they chi(phi) curves of the homopolymers, which are always located above their tangents, the dependencies for the block copolymers exhibit it maximum in the range of moderate polymer concentrations, where the heats of dilution are close to athermal ill the range of low phi values but become pronouncedly endoiliernial rot high phi values These Findings call be well modeled by all approach considering the phenomena of chain connectivity and conformational relaxation of polymers , If one accounts for the unfavorable interactions between the monomeric units of the different blocks

Experimentally obtained islands of immiscibility are reported for the systems PS/PVME/THF at 20 degrees C and for PS/PVME/CH at 55 degrees C (PS: polystyrene, PVME: poly(vinyl methyl ether), THE tetrahydrofuran, CH: cyclohexane). THF is a good solvent and CH is a marginal solvent for both polymers. In the case of THF, information on the Flory-Huggins interaction parameters of the three binary subsystems suffices for a qualitative prediction of the phase behavior of the ternary system. Quantitative agreement can be achieved by means of composition-independent ternary interaction parameters. For the marginal solvent CH, the exclusive use of binary interaction parameters wrongly predicts complete miscibility of all three components. In this case, one ternary interaction parameter must be treated as a function of composition in order to match experiment and theory. On the basis of the present results, it can be concluded that the preparation of homogeneous mixtures with arbitrary composition from a pair of compatible polymers and a common solvent is only possible on rare occasions.