Immunostimulatory activity of polysaccharide-poly(I:C) nanoparticles

Cataloged from PDF version of article.Immunostimulatory properties of mushroom derived polysaccharides (PS) as stand-alone agents were tested. Next. PS were nanocomplexed with polyI:C (pIC) to yield stable nanoparticles around 200 nm in size evidenced by atomic force microscopy and dynamic light scattering analyses. PSs were selectively engaged by cells expressing TLR2 and initiated NF kappa B dependent signaling cascade leading to a Th1-biased cytokine/chemokine secretion in addition to bactericidal nitric oxide (NO) production from macrophages. Moreover, cells treated with nanoparticles led to synergistic IL6, production and upregulation of TNF alpha, MIP3 alpha, IFN gamma and IP10 transcript expression. In mice, PS-Ovalbumin-pIC formulation surpassed anti-OVA IgG responses when compared to either PS-OVA or pIC-OVA mediated immunity. Our results revealed that signal transduction initiated both by TLR2 and TLR3 via co-delivery of pIC by PS in nanoparticle depot delivery system is an effective immunization strategy. The present work implicate that the PS and nucleic acid based nanoparticle approach along with protein antigens can be harnessed to prevent infectious diseases. (C) 2011 Elsevier Ltd. All rights reserve

Preparation and characterization of poly(ethylene terephthalate) powder-filled high-density polyethylene in the presence of silane coupling agents

Micron-size crystalline particles of Poly(ethylene terephthalate) (PET), obtained from PET bottles by crystallization and grinding, were used as a filler in high-density polyethylene (HDPE). The composite of PET particle-filled HDPE was prepared by melt mixing at 190 degreesC, which was well below the melting temperature of PET. Silane coupling agents (SCAs) were used to enhance the interaction between PET and HDPE in the composite. A chain extender (CE) and maleic anhydride (MA) were also used to provide further interaction with SCAs between these two materials. The ultimate tensile strength, especially at highest content 40% PET-filled HDPE, and the impact strength of SCAs-treated PET-filled HDPE was found to be highly improved compared to untreated PET filling into HDPE. Dynamic mechanical analyses (DMA) demonstrated that T-g of the main matrix polyethylene was depressed from 3 to 10 degreesC. Scanning electron microscopy (SEM) studies indicated a strong interaction between PET powder and HDPE when SCAs were present in the system. (C) 2000 John Wiley & Sons, Inc

A STUDY ON THE YIELD STRESS OF PERLITE-FILLED HIGH-DENSITY POLYETHYLENES

Four different types of high-density polyethylenes were blended with expanded perlite at different compositions. Gamma-aminopropyltriethoxysilane was applied to perlite (2 wt%) from ether and water solutions to enhance the interfacial adhesion between the polymer and the filler. It was shown that silane treatment advances the yield stress with improving dispersion and increasing the interfacial adhesion of the filler with the polymer matrix. The experimental results were then checked with the expression of Turcsanyi et al.'s

Radiation grafting of various water-soluble monomers on ultra-high molecular weight polyethylene powder. Part III: Preparation of compression moulded films, and water-uptake and morphological studies

Compression moulded films were obtained from PAA, PMAA, PAAm, PNDAAm and PVP radiation grafted ultrahigh molecular weight polyethylene (UHMWPE) powders. Mechanical properties and water-uptake of PVP and PNDAAm grafted UHMWPE were found to be distinctly better than PAA, PMAA and PAAm ones. The former group showed almost complete melting and flow during compression moulding compared with the latter group. Hence, the mechanical properties of this group were found to be better than the others. Important parameters affecting the film formation appeared as H-bonding ability and also the compatibility between grafting polymer and UHMWPE. Per cent water-uptake of films increase with the grafting level and approaches 30% at most for all types of films except PMAA one. High per cent water-uptake results of PAA and PAAm cases should be taken cautiously due to incomplete flowing during compression in film preparation. SEM analysis revealed incomplete melting and flow for the case of PAA, PMAA and PAAm-co-UHMWPE resulting in pores and holes in the final films while homogeneous films were obtained for the case of PVP and PNDAAm

Graft copolymerization of p-acryloyloxybenzoic acid and p-methacryloyloxybenzoic acid onto isotactic polypropylene and their thermal properties: Part I

The polymerization and grafting of the monomers p-acryloyloxybenzoic acid and p-methacryloyloxybenzoic acid were studied. Poly(acryloyloxybenzoic acid) was obtained by gamma-radiation-induced solution polymerization and bulk melt polymerization initiated by dicumyl peroxide. Poly(methacryloyloxybenzoic acid) could be obtained only by bulk melt polymerization. The graft copolymerization of the monomers onto isotactic polypropylene was carried out in bulk. The maximum grafting was reached in shorter times at higher temperatures, and it also increased with the concentration of the monomers in the reaction medium. The thermal and crystallization behavior of the graft copolymers was studied with differential scanning calorimetry and wide-angle X-ray diffraction. The graft copolymerization of p-acryloyloxybenzoic acid did not have any influence on the formation of both alpha-forms (monoclinic) of polypropylene, whereas p-methacryloyloxybenzoic acid led to the alpha(2) form. The beta-crystalline modification (hexagonal) formed in poly(acryloyloxybenzoic acid)-g-polypropylene products at 185 degrees C and at higher grafting temperatures and also in the second run of differential scanning calorimetry studies after fast cooling. The beta form was not observed in graft copolymers of poly(methacryloyloxybenzoic acid). (C) 2007 Wiley Periodicals, Inc

MELT BLENDING OF ULTRA-HIGH-MOLECULAR-WEIGHT AND HIGH-DENSITY POLYETHYLENE - THE EFFECT OF MIXING RATE ON THERMAL, MECHANICAL, AND MORPHOLOGICAL PROPERTIES

The blends of two different ultra high molecular weight polyethylenes (UHMWPE) and high density polyethylene (HDPE) were prepared in melt at different compositions and mixing rates in Brabender Torque Rheometer. The temperature build-up due to the internal friction during melt blending was recorded and evaluated with respect to the change in the torque. The temperature at maximum torque was considered the fusion point temperature of the UHMWPE in the blend. This fusion point temperature was found to depend on the composition, mixing rate, and molecular weight. The effect of mixing rate on the mechanical properties (measured as yield and tensile strengths and elongation at break), thermal oxidative degradation and melting behavior were studied. The morphology of the blends were investigated by optical microscopy

Preparation and characterization of ultrahigh molecular weight polyethylene and polyisoprene solvent-cast blend films

This study covers the preparation of noncrosslinked and crosslinked solvent-cast blend films of ultrahigh molecular weight polyethylene (UHMWPE) and polyisoprene rubber (PIR) and their mechanical, thermal, IR spectroscopic, and morphological characterizations. Solvent-cast films of polymer blends with 0, 10, 20, 35, 50, and 65% PIR composition were prepared by vigorous stirring from a hot decalin solution. The films were crosslinked chemically by using acetophenone as a crosslinking agent under UV radiation. The mechanical properties, measured as ultimate properties and tensile modulus, were found to decrease with PIR content but crosslinking was found to enhance the ultimate strength and tensile modulus. DSC results revealed that melting point of UHMWPE remains almost constant in blends. However, upon crosslinking, the melting point of UHMWPE is depressed almost 5 degrees C. We observed a similar trend in the enthalpy change of the melting of UHMWPE and the variation of percent crystallinity in UHMWPE. Scanning electron microscopy (SEM) studies on the fractured surfaces of the blends showed that the fibrillar texture is present in both crosslinked and noncrosslinked blends. The crosslinking appeared to be through oxygen linkages, which are preferentially conjugated to double bonds, in addition to the possible carbon-carbon crosslinks. (C) 1998 John Wiley & Sons, Inc

Melt blending of poly(ethylene terephthalate) with polypropylene in the presence of silane coupling agent

A silane coupling agent (SCA) was used as a compatibilizer for polypropylene-poly(ethylene teraphthalate) (PP-PET) blends with 20, 40, 50, and 60% PET compositions by weight. PP-PET mixtures were blended with and without an SCA by a single-screw extruder. The effect of silane modification on the tensile and impact properties of the blends was investigated. The morphology and thermal behavior of the blends were examined with scanning electron microscopy (SEM) and differential scanning calorimetry (DSC), respectively. The presence of the SCA used in this work extensively improved the mechanical properties of the blends. Mechanical properties were found to be highly de-pendent on the numbers Of extrusions. SEM studies showed that substantially different morphology with better adhesion existed when SCA-treated blends were compared to non-treated PP-PET blends. The presence of individual melting temperatures of the polymers in all compositions with no significant T,, depression indicated that PET and PP were crystallized separately. (C) 2003 Wiley Periodicals, Inc

A STUDY ON BLENDS OF LOW AND HIGH-DENSITY POLYETHYLENES - EFFECT OF MIXING TIME ON MECHANICAL, THERMAL-PROPERTIES AND OXIDATIVE-DEGRADATION

In this study, polyethylenes of high melt flow index LDPE and a medium melt flow index HDPE were melt blended. The mechanical, thermal properties and the thermal oxidative degradation were studied as a function of four different mixing times. The results were evaluated according to the blend composition and time of mixing. The tensile strength was found to be affected mostly by mixing time as compared with the elongation at break while the modulus remained unchanged with time of mixing. The thermal oxidative degradation of the blends were found to be less than the corresponding pure components

Study on the properties of crosslinking of poly(ethylene oxide) and hydroxyapatite-poly(ethylene oxide) composite

This study covers the crosslinking of poly-(ethylene oxide) (PEO) and its composite with calcium hydroxyapatite (HA), their mechanical and swelling properties, and morphology. Sheets of the composites of PEO (two different grades with M-v: 5x10(6) and 2x10(5)) and HA and neat PEO were prepared by compression molding. The prepared composite. and. PEO (0.1-mm-thick) sheets were crosslinked with exposure of UV-irradiation in the presence of a photoinitiator, acetophenone (AP). This simple method for crosslinking, induced by UV-irradiation in the presence of AP, yielded PEO with gel content up to 90%. Gel content, equilibrium swelling ratio, and mechanical and morphological properties of the low molecular weight polyethylene oxide (LMPEO)-HA crosslinked and uncrosslinked composites were evaluated. Although the inclusion of HA into LMPEO inhibits the extent of crosslinking, the LMPEO-HA composite with 20% HA by weight shows the highest gel content, with appreciable equilibrium swelling and mechanical strength. The growth of HA in simulated body fluid solutions on fractured surfaces of LMPEO and also LMPEO-HA was found to be very favorable within short times. The dimensional stability of these samples was found to be satisfactory after swelling and deposition experiments. The good compatibility between the filler hydroxyapatite and poly(ethylene oxide) makes this composite a useful tissue-adhesive material. (C) 2003 Wiley Periodicals, Inc