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The most frequent neutralisation procedure, applied on chitosan (CS) films includes treatment with NaOH base. Such treatment endows CS films with stability in water, yet, same can significantly decrease the film performance. In the present paper, we investigate Mg(OH)2 nanoparticles as a neutralisation agent for CS solutions followed by casting into films. This is combined and compared with classical casting and film drying from non-neutralized solutions followed by NaOH treatment after film formation. The influence on the properties of resulting films is investigated in detail and large differences are found for structure and barrier properties. The stable, opaque-to-transparent CS films (depending on Mg(OH)2 content and post-treatment) were obtained by facile casting method of neat CS or CS–Mg(OH)2 dispersions, in the complete absence of cross-linkers and plasticizers. FTIR data demonstrate the Mg(OH)2 and NaOH deprotonation effect, and strongly suggest intensive H-bonding interaction between CS and Mg(OH)2. X-ray photoelectron spectroscopy showed differences in the hydroxide content and protonation of CS nitrogen. The reduction of surface roughness and increase of homogeneity, the tensile strength and elongation, as well as thermal stability and excellent oxygen barrier properties were measured for CS enclosing the Mg(OH)2 nanoparticles. Further treatment with 1 M NaOH causes re-packing of CS polymer chains, improving the crystallinity and water vapour barrier properties, degrading the mechanical properties by increasing the films brittleness and increasing the char formation due to reduced thermal stability. [ABSTRACT FROM AUTHOR]

The aim of this study was to develop a material based on cellulose acetate and chitosan fabricated via a simple non-hazardous solvent casting method and modified them by deacetylation approach. Both the modified and unmodified chitosan/cellulose acetate films were well characterized in terms of their morphology, chemical moieties and wettability using field emission scanning electron microscope, attenuated total reflectance-Fourier transform infrared spectroscope and static water contact angle, respectively. A quantitative analysis such as charge titration experiments was conducted on the films to determine the number of accessible charges in the films which has a significant role in the adsorption phenomenon. Subsequently, the films developed by different compositions of cellulose acetate and chitosan were modified for the first time using deacetylation process under the optimized condition and characterized them using the same above-mentioned technologies. The impact of both unmodified and modified cellulose acetate/chitosan film on freshwater remediation was investigated by adsorbing two known dye such as acid orange 7 and brilliant yellow from the aqueous solution. An enhanced removal efficiency (% R) and adsorption capacity [qe (mg/g)] were observed on both the dyes (99.8% and 9.98 mg/g for acid orange 7, 99.7% and 9.38 mg/g for brilliant yellow) using modified cellulose acetate/chitosan films. The result obtained from this research proved that the modified cellulose acetate/chitosan film was made by acetic acid and water mixture can be used as a potential candidate for anionic dye water treatment. [ABSTRACT FROM AUTHOR]

Abstract: Novel multifunctional bio-based nanofibrous mats were prepared which contain the commonly used pain reducing local anesthetic benzocaine (BZC) and the in situ pH-detecting dye bromocresol green (BCG). These can serve as a dual nano-carrier system for wound healing applications, especially in the treatment of infected wounds. BZC and BCG were introduced into cellulose acetate (CA) based nanofibers using a single-step needleless electrospinning process. The resulting CA nanofibers show a homogenous fiber diameter distribution around 600 nm, hydrophobicity with a water contact angle of 134°, and simultaneous porosities on the nano-micro- scale. In spite of their hydrophobic character, the nanofibrous mats showed a huge water absorption capacity (1657%), as well as good stability at physiological pH (negligible degradation). All the mentioned properties remain unchanged upon the inclusion of either BZC or BCG. Results from the in vitro drug release studies showed a pH dependent (i.e. controllable) release of BZC, and confirmed the expected maximum drug release rate at pH 9.0, which would correspond clinically to the pH of an infected wound. The accompanying color change of the nanofibrous mats, provided through the encapsulated BCG (from yellow to blue), is noticeable within a few seconds after the pH changes from acidic to alkaline. This rapid response of NSAID, together with the visible absorption of included dye, show the capacity of the proposed nanofibrous mats as an in situ pH-detecting system. Finally, the biocompatibility of the proposed nanofibrous mats was proven using human skin fibroblast cells, confirming their potential to be used in wound treatment.Graphical abstract: [ABSTRACT FROM AUTHOR]

The loss of tissue is still one of the most challenging problems in healthcare. Efficient laboratory expansion of skin tissue to reproduce the skins barrier function can make the difference between life and death for patients with extensive full-thickness burns, chronic wounds, or genetic disorders such as bullous conditions. This engineering has been initiated based on the acute need in the 1980s and today, tissue-engineered skin is the reality. The human skin equivalents are available not only as models for permeation and toxicity screening, but are frequently applied in vivo as clinical skin substitutes. This review aims to introduce the most important recent development in the extensive field of tissue engineering and to describe already approved, commercially available skin substitutes in clinical use. [ABSTRACT FROM AUTHOR]

The formation of endothelial cell monolayer on prosthetic implants has not sufficiently explored. The main reasons leading to the development of thrombosis and/or intimal hyperplasia is the lack of endothelialization. In the present work, we have studied the influence of oxygen and fluorine plasma treatment of polyethylene terephthalate (PET) polymers on human microvascular endothelial cell adhesion and proliferation. We characterized the polymer surface, wettability, and oxidation potential upon plasma treatment. Moreover, binding of serum and media compounds on PET surface was monitored by Quartz crystal microbalance method, X-ray photoelectron spectroscopy, and atomic force microscopy. Cell adhesion and morphology was assessed by light and scanning electron microscopy. The influence of plasma treatment on induction of cellular oxidative stress and cell proliferation was evaluated. The results obtained showed that treatment with oxygen plasma decreased the oxidation potential of the PET surface and revealed the highest affinity for binding of serum components. Accordingly, the cells reflected the best adhesion and morphological properties on oxygen-treated PET polymers. Moreover, treatment with oxygen plasma did not induce intracellular reactive oxygen species production while it stimulated endothelial cell proliferation by 25% suggesting the possible use of oxygen plasma treatment to enhance endothelialization of synthetic vascular grafts. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 102A: 2305-2314, 2014. [ABSTRACT FROM AUTHOR]

Non-woven viscose samples were treated for 5 min with non-equilibrium ammonia plasma. Plasma-induced properties often gradually change with time, thereby limiting the durability of surfaces for industrial application. The modified samples were stored for 10 and 30 days under air and argon, i.e. possible gases for maintaining plasma-gained absorption kinetics and biostatic activity. XPS results for the aged samples showed practically the same composition as for the freshly-treated samples, regardless of storage gases. Any aging of the plasma-induced hydrophilicity was not evident as the absorbency rate, capacity, and contact angles remained almost unchanged within one month, independent of the storage gases used. Biostatic activity endured almost unaltered over 10 days, whereas it decreased during 30 days, being more pronounced within argon than air. The results from absorption kinetics for both the saline solution and the synthetic exudate, as well as from microbiological analyses, revealed that the plasma-induced modifications of the non-woven material remained fairly unaltered for at least one month when stored within air, thus making this technique attractive for wound dressing applications. [ABSTRACT FROM PUBLISHER]

Viscose non-woven was treated by NH3 plasma. Different exposure times were used in order to find the optimum conditions for simultaneously improved hydrophilicity and antimicrobial activity, as desired effects by wound dressings. Both chemical and morphological modifications were studied by X-ray photoelectron spectroscopy and atomic force microscopy, respectively, revealing functionalization with nitrogen groups as well as formation of rich morphology at sub-micrometer scale. The wetting rise curves increased from 0.04 g2 s–1 for non-treated material to 1 g2 s−1 after prolonged treatment. The water contact angle decreased almost linearly with treatment time from 90° for non-treated samples to about 40° for samples treated for 140 s and remained rather constant thereafter. The AATCC 100–1999 standard test revealed reduction on all used bacteria, more pronounced for Gram-negative, that is, E. coli and P. aeruginosa, then for Gram-positive, that is, a significant for S. aureus and a marginal for E. faecalis. [ABSTRACT FROM PUBLISHER]

The aim of this research work was to study the surface properties and sorption characteristics of differently treated regenerated cellulose fabrics. Surface modifications of viscose, modal and lyocell samples caused by using standard chemical pre-treatment procedures were compared to an alternative activation procedure by applying low pressure oxygen plasma treatment. The elemental chemical composition of the modified fabric surfaces was investigated using X-ray photoelectron spectroscopy (XPS), while hydrophilic/hydrophobic properties were evaluated by determining the water contact angles, as well as thoroughly analysed using Owens–Wendt surface energy (SFE) and surface polarity investigations.Standard chemical and also plasma treatments changed the surface chemistry of cellulose. Bleaching and alkaline treatments increased the surface carboxylic acid content by approximately 4.8% while plasma treatment increased it by approximately 9.7%. As a consequence, higher hydrophilicity arises as proved by water contact angle decrease; i.e. 24% (61°) after standard chemical treatments and 70% (20°) after plasma treatment. Both chemical treatments increase the SFE and polar components, while the reduction of dispersive components was less pronounced. The oxygen activation treatment has the greatest influence on the SFEs of the samples as well as on polarity of the samples. [ABSTRACT FROM PUBLISHER]

Galactoglucomannans (GGMs) are water-soluble polysaccharides released and accumulated in process waters in the production of thermomechanical pulp. The general trend in the forestry industry is moving towards bio-refineries, for example utilizing these hemicelluloses as bioactive substances. At present, there is no industrial use of wood-derived mannans. In this study, GGMs extracted from thermomechanical pulp, as well as further carboxymethyl-ated galactoglucomannans (CM-GGMs), were sulfated to increase their antithrombotic properties. The products were characterized with Fourier transform infrared spectroscopy, nuclear magnetic resonance and capillary electrophoresis. The carbohydrate composition and sulfur amounts were determined. The products' total charges were determined by polyelectrolyte titrations and their antithrombotic effect was measured based on the activated partial thromboplastin time. The results showed a significant increase in the antithrombotic effect of the sulfated galactoglucomannans from spruce wood and thus a potential new use for wood-derived mannans. [ABSTRACT FROM AUTHOR]

The aim of this study was to setup a method for detection and quantification of monosaccharide components in technical galactoglucomannas (T-GGM) from spruce wood using capillary zone electrophoresis (CZE). CZE technique was optimised regarding borate buffer concentrations, EOF modifier application, and system pH. Aqueous solution of T-GGM was chemically hydrolysed by sulphuric acid, in an autoclave. In this way obtained monosaccharides were derivatized with 4-amino benzoic acid ethyl ester via reductive amination using sodium cyanoborohydride. The results of the optimisation procedure showed that the borate buffers at lowest concentrations (100 and 200 mM) with acetonitrile addition as EOF modifier gave the optimal measurement results, as it showed sufficient separation at relatively short migration times. The amounts of single monosaccharide components in the T-GGM samples obtained by the optimised CZE procedure were practically the same in comparison to the results of the well established HPLC-anion exchange chromatography. On the basis of this research, it was concluded that the capillary zone electrophoresis is an efficient analytical procedure for the characterisation of galactoglucomannans derived from softwoods. [ABSTRACT FROM AUTHOR]

The article deals with a study which prepared nanocomposite fibers based on polypropylene (PP) polymer with different content of nanofiller. In preparing PP nanocomposite fibers, montmorillonite modified by N,N-di-methyl-N,N dioctadecylammonium cations was employed. It was noted that the zeta potential (ZP) value of nanofilled fibers was affected by the addition of nanoparticles. Meanwhile, the different concentrations of nanofiller have no significant impact on isoelectric point (IEP).

Modification and functionalization of polymer surface properties is desired in numerous applications, and a standard technique is a treatment with non-equilibrium gaseous plasma. Fluorinated polymers exhibit specific properties and are regarded as difficult to functionalize with polar functional groups. Plasma methods for functionalization of polyvinylidene fluoride (PVDF) are reviewed and different mechanisms involved in the surface modification are presented and explained by the interaction of various reactive species and far ultraviolet radiation. Most authors used argon plasma but reported various results. The discrepancy between the reported results is explained by peculiarities of the experimental systems and illustrated by three mechanisms. More versatile reaction mechanisms were reported by authors who used oxygen plasma for surface modification of PVDF, while plasma sustained in other gases was rarely used. The results reported by various authors are analyzed, and correlations are drawn where feasible. The processing parameters reported by different authors were the gas pressure and purity, the discharge configuration and power, while the surface finish was predominantly determined by X-ray photoelectron spectroscopy (XPS) and static water contact angle (WCA). A reasonably good correlation was found between the surface wettability as probed by WCA and the oxygen concentration as probed by XPS, but there is hardly any correlation between the discharge parameters and the wettability. [ABSTRACT FROM AUTHOR]

Starch is the second most abundantly available natural polymer in the world, after cellulose. If we add its biodegradability and non-toxicity to the natural environment, it becomes a raw material very attractive for the food and non-food industries. However, in the latter case, mainly due to the high hydrophilicity of starch, it is necessary to carry out many more or less complex operations and processes. One of the fastest growing industries in the last decade is the processing of biodegradable materials for packaging purposes. This is mainly due to awareness of producers and consumers about the dangers of unlimited production and the use of non-degradable petroleum polymers. Therefore, in the present review, an attempt was made to show the possibilities and limitations of using starch as a packaging material. The most important physicochemical features of this biopolymer are discussed, and special attention is paid to more or less environmentally friendly methods of improving its processing properties. [ABSTRACT FROM AUTHOR]

Several naturally occurring biological systems, such as bones, nacre or wood, display hierarchical architectures with a central role of the nanostructuration that allows reaching amazing properties such as high strength and toughness. Developing such architectures in man-made materials is highly challenging, and recent research relies on this concept of hierarchical structures to design high-performance composite materials. This review deals more specifically with the development of hierarchical fibres by the deposition of nano-objects at their surface to tailor the fibre/matrix interphase in (bio)composites. Fully synthetic hierarchical fibre reinforced composites are described, and the potential of hierarchical fibres is discussed for the development of sustainable biocomposite materials with enhanced structural performance. Based on various surface, microstructural and mechanical characterizations, this review highlights that nano-objects coated on natural fibres (carbon nanotubes, ZnO nanowires, nanocelluloses) can improve the load transfer and interfacial adhesion between the matrix and the fibres, and the resulting mechanical performances of biocomposites. Indeed, the surface topography of the fibres is modified with higher roughness and specific surface area, implying increased mechanical interlocking with the matrix. As a result, the interfacial shear strength (IFSS) between fibres and polymer matrices is enhanced, and failure mechanisms can be modified with a crack propagation occurring through a zig-zag path along interphases. [ABSTRACT FROM AUTHOR]

Hyaluronic acid (HA), a high-molecular-weight linear polysaccharide, restricts solute transport through the interstitial space. Albumin and hydroxyethyl starch (HES) solutions are used to correct the decrease of blood volume during surgery, but may leak into the interstitial space under inflammation conditions. Given the possibility that the structure of HA may be affected by adjacent macromolecules, this study tested whether albumin and HES (Mw 130,000) exert different effects on solute permeation through sodium hyaluronic acid (NaHA: Mw 1.3 × 106) solution. To this end, permeation of Orange G, a synthetic azo dye (Mw 452), into NaHA solutions containing albumin or HES over time was assessed. The amount of time it took for the relative absorbance of Orange G to reach 0.3 (T0.3) was determined in each NaHA solution relative to the reference solution (i.e., colloid solution without NaHA). Relative T0.3 values of albumin were larger than those of HES for 0.1% NaHA solution (3.33 ± 0.69 vs. 1.16 ± 0.08, p = 0.006, n = 3) and 0.2% NaHA solution (1.95 ± 0.32 vs. 0.92 ± 0.27, p = 0.013, n = 3). This finding may help in the selection of an appropriate colloid solution to control drug delivery into the interstitial space of cancer tissue under inflammation conditions. [ABSTRACT FROM AUTHOR]