Influence of the covalent immobilization of graphene oxide in poly(vinyl alcohol) on human osteoblast response.

The differences in the response of human Saos-2 osteoblasts to nanocomposites of poly(vinyl alcohol) (PVA) and 1.5wt.% graphene oxide (GO) prepared by covalent linking (PVA/GO-c) and simple blending (PVA/GO-m) have been evaluated through different biocompatibility parameters.

Bioassay of cyanoacrylate tissue adhesives used for intraperitoneal mesh fixation.

Aims: This study examines the intraperitoneal behavior of two cyanoacrylate tissue adhesives: Ifabond and a new, non-marketed octyl cyanoacrylate adhesive (OCA) used for the intraperitoneal fixation of a laminar expanded polytetrafluoroethylene (ePTFE) mesh.

Material And Methods: In 36 New Zealand White rabbits, 3 × 3 cm (n = 24) or 1.5 × 3 cm (n = 12) fragments of ePTFE mesh (Preclude , Gore, Flagstaff, USA) were fixed to the parietal peritoneum using OCA or Ifabond .

Chitosan-tripolyphosphate nanoparticles as Arrabidaea chica standardized extract carrier: synthesis, characterization, biocompatibility, and antiulcerogenic activity.

Natural products using plants have received considerable attention because of their potential to treat various diseases. Arrabidaea chica (Humb. & Bonpl.

Bioactive bilayered dressing for compromised epidermal tissue regeneration with sequential activity of complementary agents.

The article deals with the design, preparation, and evaluation of a new bilayered dressing for application in the healing of compromised wounds. The system is based on the sequential release of two complementary bioactive components to enhance the activation of the regeneration of dermal tissue. The internal layer is a highly hydrophilic and biodegradable film of gelatin and hyaluronic acid (HG), crosslinked with the natural compound genipin, which reacts with the amine groups of gelatin.

Effect on in vitro cell response of the statistical insertion of N-(2-hydroxypropyl) methacrylamide on linear pro-dendronic polyamine's gene carriers.

Statistical copolymers of N-(2-hydroxypropyl) methacrylamide (HPMA) and the dendronic methacrylic monomer 2-(3-(Bis(2-(diethylamino)ethyl)amino)propanamido)ethyl methacrylate (TEDETAMA, derived from N,N,N',N'-tetraethyldiethylenetriamine, TEDETA), were synthesized through radical copolymerization and evaluated in vitro as non-viral gene carriers. Three copolymers with nominal molar percentages of HPMA of 25%, 50% and 75% were prepared and studied comparatively to the positive controls poly-TEDETAMA and hyperbranched polyethyleneimine (PEI, 25kDa). Their ability to complex DNA at different N/P molar ratios, from 1/1 up to 8/1, was determined through agarose gel electrophoresis and Dynamic Light Scattering.

Use of alginate, chitosan and cellulose nanocrystals as emulsion stabilizers in the synthesis of biodegradable polymeric nanoparticles.

Biopolymeric nanoparticles (NPs) based on a biodegradable poly(DL-Lactide-co-Glycolide) PLGA copolymer matrix combined with alginate, chitosan and nanostructured cellulose crystals as three different natural emulsion stabilizers, were synthesized by a double emulsion (water/oil/water) method with subsequent solvent evaporation. The morphological, thermal, chemical and rheological properties of the novel designed NPs and the effect of the different emulsion stabilizers used during the synthesis were deeply investigated in order to optimize the synthesis procedure and the development of biodegradable nanoparticles coated with natural polymers. The morphological analysis of the produced nanoparticles showed that all the different formulations presented a spherical shape with smooth surface.

Synergistic effect of pendant hydroxypropyl and pyrrolidine moieties randomly distributed along polymethacrylamide backbones on in vitro DNA-transfection.

In this work, the cationic monomer N-ethyl pyrrolidine methacrylamide (EPA) was copolymerized with the neutral monomer N-hydroxypropyl methacrylamide (HPMA) at different molar ratios obtaining linear random copolymers that were characterized and evaluated in vitro as non-viral gene carriers using murine Swiss 3T3 fibroblasts. The copolymers with excess or equimolar amount of EPA were able to complex DNA forming stable polyplexes with an average size between 50 and 200 nm, while the copolymers with an excess of HPMA do not. Cell viability was shown to depend on the EPA/HPMA molar ratio, exhibiting the equimolar copolymer poly (EPA-co-HPMA) 50:50 (EPA50) a full cytocompatibility, similar to the HPMA-rich systems.

Pseudo-double network hydrogels with unique properties as supports for cell manipulation.

Pseudo-double network hydrogels based on vinylpyrrolidone and anionic methacrylic units were prepared, for the first-time, via a simple one step radical polymerization procedure using thermal or photoinitiation. These networks showed improved mechanical properties, in the hydrated state, compared with their single network cousins and were capable of hosting cells to confluence. Rapid cell detachment can be induced through simple mechanical agitation and the cell sheets can be transplanted easily without the need for a cell superstrate.

Temporal and spatial patterning of transgene expression by near-infrared irradiation.

We investigated whether near-infrared (NIR) light could be employed for patterning transgene expression in plasmonic cell constructs. Hollow gold nanoparticles with a plasmon surface band absorption peaking at ∼750 nm, a wavelength within the so called "tissue optical window", were used as fillers in fibrin-based hydrogels. These composites, which efficiently transduce NIR photon energy into heat, were loaded with genetically-modified cells that harbor a heat-activated and ligand-dependent gene switch for regulating transgene expression.

Poly(3-hydroxybutyrate)/ZnO bionanocomposites with improved mechanical, barrier and antibacterial properties.

Poly(3-hydroxybutyrate) (PHB)-based bionanocomposites incorporating different contents of ZnO nanoparticles were prepared via solution casting technique. The nanoparticles were dispersed within the biopolymer without the need for surfactants or coupling agents. The morphology, thermal, mechanical, barrier, migration and antibacterial properties of the nanocomposites were investigated.

High-performance aminated poly(phenylene sulfide)/ZnO nanocomposites for medical applications.

An aminated poly(phenylene sulfide) derivative (PPS-NH2) has been melt-blended with different contents of ZnO nanoparticles, and the morphology, thermal, mechanical, tribological, antibacterial, and dielectric properties of the resulting nanocomposites have been investigated. The nanoparticles were dispersed within the matrix without the need for surfactants or coupling agents. A gradual rise in the crystallization temperature and the degree of crystallinity was found with increasing ZnO loading, confirming that the nanoparticles act as nucleating agents for PPS-NH2 crystallization.

ZnO-reinforced poly(3-hydroxybutyrate-co-3-hydroxyvalerate) bionanocomposites with antimicrobial function for food packaging.

Biodegradable nanocomposites were prepared by adding ZnO nanoparticles to bacterial polyester poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) via solution casting technique. The morphology, thermal, mechanical, antibacterial, barrier, and migration properties of the nanocomposites were analyzed. The nanoparticles were uniformly dispersed within PHBV without the aid of coupling agents, and acted effectively as nucleating agents, raising the crystallization temperature and the level of crystallinity of the matrix while decreasing its crystallite size.

Development of nanocomposites reinforced with carboxylated poly(ether ether ketone) grafted to zinc oxide with superior antibacterial properties.

Novel poly(ether ether ketone) (PEEK) based nanocomposites have been fabricated via melt-blending by addition of a carboxylated polymer derivative covalently grafted onto the surface of hydroxyl-terminated ZnO nanoparticles. Their morphology, thermal, mechanical, tribological, and antibacterial properties have been analyzed and compared with those of composites reinforced with pristine ZnO. The Fourier transform infrared (FT-IR) spectra corroborate the success of the grafting reaction, showing the appearance of signals related to ester linkages.

Novel hydrogels of chitosan and poly(vinyl alcohol)-g-glycolic acid copolymer with enhanced rheological properties.

Poly(vinyl alcohol) (PVA) has been grafted with glycolic acid (GL), a biodegradable hydroxyl acid to yield modified poly(vinyl alcohol) (PVAGL). The formation of hydrogels at pH = 6.8 and physiological temperature through blending chitosan (CS) and PVAGL at different concentrations has been investigated.

PVA bio-nanocomposites: a new take-off using cellulose nanocrystals and PLGA nanoparticles.

The formation of a new generation of hybrid bio-nanocomposites is reported: these are intended at modulating the mechanical, thermal and biocompatibility properties of the poly(vinyl alcohol) (PVA) by the combination of cellulose nanocrystals (CNC) and poly (D,L-lactide-co-glycolide) (PLGA) nanoparticles (NPs) loaded with bovine serum albumin fluorescein isothiocynate conjugate (FITC-BSA). CNC were synthesized from microcrystalline cellulose by hydrolysis, while PLGA nanoparticles were produced by a double emulsion with subsequent solvent evaporation. Firstly, binary bio-nanocomposites with different CNC amounts were developed in order to select the right content of CNC.

Carbon nanotube buckypaper reinforced acrylonitrile-butadiene-styrene composites for electronic applications.

Novel acrylonitrile-butadiene-styrene (ABS) nanocomposites reinforced with pristine or functionalized single- or multiwalled carbon nanotube buckypaper (BP) sheets were manufactured via hot-compression and vacuum infiltration. Their morphology, thermal, mechanical, and electrical properties were comparatively investigated. Scanning electron microscopy and thermogravimetric analysis showed that the infiltration process leads to better BP impregnation than the hot-press technique.

Oxidized dextrins as alternative crosslinking agents for polysaccharides: application to hydrogels of agarose-chitosan.

Hydrogel networks that combine suitable physical and biomechanical characteristics for tissue engineering scaffolds are in demand. The aim of this work was the development of hydrogel networks based on agarose and chitosan using oxidized dextrins as low cytotoxicity crosslinking agents, paying special attention to the study of the influence of the polysaccharide composition and oxidation degree of the dextrins in the final characteristics of the network. The results show that the formation of an interpenetrating or a semi-interpenetrating polymer network was mainly dependent on a minimum agarose content and degree of oxidation of dextrin.

Poly(lactic acid)/natural rubber/cellulose nanocrystal bionanocomposites. Part II: properties evaluation.

The crystallization, mechanical and biodegradation properties of poly(lactic acid)/natural rubber/cellulose nanocrystals (CNC) bionanocomposites were evaluated. Three types of CNC were used in this study, one unmodified (CNC), long alkyl chain grafted CNC (C18-g-CNC) and PLA grafted CNC (PLA-g-CNC). The CNC modifications determined the affinity of the nanocrystals toward the polymers and reflected on the ultimate properties.

Poly(lactic acid)/natural rubber/cellulose nanocrystal bionanocomposites part I. Processing and morphology.

PLA/NR/cellulose nanowhisker composites were prepared using three types of cellulose nanocrystals (CNC), i.e. unmodified CNC obtained from acid hydrolysis of microcrystalline cellulose and two surface modified CNC.

Encapsulation of low molecular weight heparin (bemiparin) into polymeric nanoparticles obtained from cationic block copolymers: properties and cell activity.

Bemiparin (fractionated low molecular weight heparin)-loaded nanoparticles were prepared by two consecutive w/o emulsions and an inversion to an o/w emulsion for various polymer systems as controlled release formulations. New synthetic block copolymers, poly(methyl methacrylate-b-trimethyl aminoethyl methacrylate) (PMMA-b-PMAETMA), with controlled microstructure and molecular weight, were prepared by RAFT (Reversible Addition-Fragmentation chain-Transfer) polymerization creating a set of polymers with different amounts of cationic charges. For comparison, a non-biodegradable positively charged polymer, Eudragit® RS PO, and a biodegradable polymer poly(lactic-co-glycolic acid), PLGA, were used.

Chlorosulfonation of polystyrene substrates for bioanalytical assays: distribution of activated groups at the surface.

In this work the activation of transparent PS substrates by chlorosulfonation is described and their distribution in the subsurface region is analyzed. For this purpose XPS, FTIR-ATR and colorimetry have been used. It is shown that the electrophilic aromatic substitution of polystyrene in pure chlorosulfonic acid is extremely quick with complete surface coverage by chlorosulfonic groups achieved after only a 10 minute reaction time at -10 °C.

bFGF interaction and in vivo angiogenesis inhibition by self-assembling sulfonic acid-based copolymers.

The antiangiogenic activity of different families of biocompatible and non-toxic polymer drugs based on 2-acrylamido-2-methylpropane sulfonic acid (AMPS) or polymethacrylic derivatives of 5-aminonaphthalen sulfonic acid (MANSA) is analyzed using directed in vivo angiogenesis assay and correlated with in vitro results. These active compounds were copolymerized with butylacrylate (BA) and N-vinylpyrrolidone in order to obtain two families of copolymers with different properties in aqueous media. The most hydrophobic copolymers poly(BA-co-MANSA) and poly(BA-co-AMPS) formed amphiphilic copolymers and presented micellar morphology in aqueous media.

End functionalized polymeric system derived from pyrrolidine provide high transfection efficiency.

Chemical architecture and functionality play an important role in the physico-chemical properties of cationic polymers with applications as gene vectors. In this study, linear homopolymers of N-ethyl pyrrolidine methacrylamide (EPA), copolymers of EPA with N,N-dimethylacrylamide (DMA) and oligomers of EPA were synthesized, and the resulting structures were evaluated for their transfection efficiency as non-viral gene vectors. Specifically, polymer species with high and low molecular weights (120-2.

Anti-angiogenic activity of heparin-like polysulfonated polymeric drugs in 3D human cell culture.

The activity of new anti-angiogenic polymeric drugs was tested in a 3D endothelial cell culture system applied as a model of angiogenesis. The assay was performed in a highly reproducible fibrin matrix that supported endothelial cell attachment, proliferation, migration, and formation of capillary-like structures. Active growth factors (FGF and/or VEGF) were added to the medium to induce the formation of blood vessel-like structures, and the effect of the active polymers was then tested by a semi-quantitative immunostaining protocol and visualized by laser-scanning confocal microscopy.

Fluid dynamics of evolving foams.

The physical properties of many multiphase systems are determined by coarsening phenomena. From raindrops to polycrystal grains and foams, the formation and stability of these systems continuously evolve towards lower-energy configurations through events such as coalescence, Ostwald ripening and drainage. Here we propose a procedure to identify and characterise key topological transformations of coarsening phenomena using a physically-based fluid dynamic framework.