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The irradiation of polymeric materials with ionizing radiation (γ-rays, X-rays, accelerated electrons, ion beams, etc.) may lead to disproportion, hydrogen abstraction, arrangements, degradation, and/or the formation of new bonds. The purpose of this paper is to evaluate the effect of gamma irradiation on some new poly(lactic acid) (PLA)-based blends and biocomposites, which is crucial when they are used for food packaging or medical purposes. The polymeric blends and biocomposites based on PLA and rosemary ethanolic extract (R) and poly(ethylene glycol) (PEG) (20 wt%) plasticized PLA, chitosan (CS) (3–6 wt%) and R (0.5 wt%) biocomposites were subjected to gamma irradiation treatment using three low γ-doses of 10, 20, and 30 kGy. The effect of irradiation was evaluated by Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), thermogravimetry (TG), chemiluminescence method (CL), migration studies, and antibacterial activity tests. It was found that in comparison with neat PLA, the gamma irradiation in the oxidative conditions of the PLA-based blends and biocomposites, causes modifications in the structure, morphology, and thermal properties of the materials depending on irradiation dose and the presence of natural additives such as rosemary and chitosan. It was established that under a gamma-irradiation treatment with dose of 10–20 kGy, the PLA materials showed minor changes in structure and properties being suitable for application in packaging and in addition after irradiation with such doses their antimicrobial activity against Escherichia coli, Staphylococcus aureus, and Salmonella typhimurium is improved. [ABSTRACT FROM AUTHOR]

This paper reports on biofunctionalisation of a poly(lactic acid) (PLA) film by surface activation through cold plasma treatment followed by coating with a chitosan-gelatin xerogel. The UV cross-linking of the xerogel precursor was simultaneously performed with the fixation onto the PLA support. This has a strong effect on surface properties, in terms of wettability, surface free energy, morphology and micromechanical features. The hydrophilic – hydrophobic character of the surface, determined by contact angle measurements, was tuned along the process, passing from moderate hydrophobic PLA to enhanced hydrophilic plasma activated surface, which favors coating adhesion, then to moderate hydrophobic chitosan-gelatin coating. The coating has a Lewis amphoteric surface, with a porous xerogel-like morphology, as revealed by scanning electron microscopy images. By riboflavin mediated UV cross-linking the chitosan-gelatin coating becomes high adhesive and with a more pronounced plasticity, as shown by AFM force-distance spectroscopy. Thus prepared surface-coated PLA supports were successfully tested for growth of dermal fibroblasts, which are known for their induction potential of chondrogenic cells, which is very important in cartilage tissue engineering. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract Polymer dispersed liquid crystal (PDLC) composites were prepared by the encapsulation of cholesteryl acetate (L-ChAc) in polyvinyl alcohol boric acid (PVAB) by microemulsion technique. The supramolecular and morphological peculiarities of the resulted composites were analyzed by polarized optical microscopy, fluorescence microscopy and scanning electron microscopy respectively. The thermal behavior of the systems was evaluated by differential scanning calorimetry and the surface characteristics in terms of wettability and surface free energy were calculated based on contact angle measurements. Circular dichroism was further used to evidence the chiroptical properties of the studied PDLCs and to have an insight on the potential interactions between the components. The ability of the composites to act as sensors for different blood analytes was preliminary tested by POM. The results indicated that PVAB facilitated a uniform distribution of the cholesteric liquid crystal as micrometric droplets with narrow polydispersity and planar anchoring. The obtained PDLCs proved moderate wettability and they showed a selective responsiveness for L or D sugars, amino acids and DNA. All these results indicated the new polymer dispersed liquid crystal systems as promising materials for biosensors building. Graphical abstract Unlabelled Image Highlights • PDLC films based on a cholesteric liquid crystal and a PVAB matrix were prepared. • The liquid crystal was anchored into the matrix as microdroplets (diameter of 5 μm). • The PDLC films showed a helical supramolecular architecture. • They revealed responsiveness to various biologic analytes. [ABSTRACT FROM AUTHOR]

The chitosan effect on the soil burial degradation of polylactic acid plasticized with tributyl o-acetyl citrate (ATBC) was studied by weight loss measurements, changes in average molecular weight and its distribution, mechanical, thermal and surface properties correlated with structural and morphological modifications. Besides the loss of transparency at the end of environmental degradation test, all composites became brittle. During degradation, Young modulus increases while elongation at break significantly decreased, mainly for the biocomposites with high content of chitosan which also showed a significant decrease of average molecular weight, increase of glass transition temperature and crystallinity degree values and decrease of cold crystallization and melting temperature when soil burial period is longer. The high content of chitosan led to increased hydrophilicity of biocomposite surfaces which favors interaction with moisture and attack of microorganisms. Chitosan as hydrophilic compound promotes the soil burial degradation of PLA. However, longer period of soil burial are necessary for totally degradation of the sheets of plasticized PLA/CS biocomposites. [ABSTRACT FROM AUTHOR]

pH-Sensitive hydrogels of 2-hydroxyethyl methacrylate/citraconic anhydride–modified collagen were obtained by free radical copolymerization/crosslinking in the presence of ammonium persulfate/N,N,N′,N′-tetramethylethylenediamine redox initiator system. Their pH-responsiveness was demonstrated by swelling behavior and ciprofloxacin release tests. Both unloaded and loaded hydrogels were characterized by Fourier transform infrared, scanning electron microscopy, and biocompatibility tests. The enzymatic degradation in the presence of Clostridium histolyticum mainly depends on initiator content. In vivo biocompatibility tests involving intraperitoneal hydrogels’ implantation in rats following the analysis by the granuloma test, leukocyte formula, immune parameters, and hepatic transaminases demonstrated their non-toxicity and biocompatibility with living tissues. The in vitro antimicrobial activity, in vivo biocompatibility, and in vitro biodegradability tests attest the possibility to use these new polymeric hydrogels with tailored properties as matrices for bioactive products in medical and pharmaceutical applications as wound care and targeting drug delivery systems. The ciprofloxacin release studies proved their potential as materials for wound dressings. [ABSTRACT FROM AUTHOR]

Poly(vinyl alcohol)/hyaluronic acid cryogels loaded with methotrexate were studied. The physical-chemical characterization of cryogels was performed by FT-IR spectroscopy, scanning electron microscopy, differential scanning calorimetry and dynamic mechanical thermal analysis. Acute toxicity and haematological parameters were determined by "in vivo" tests. The biocompatibility tests proved that the obtained cryogels showed significantly decreased toxicity and are biocompatible. The pH-responsiveness of the swelling behaviour and of the methotrexate release from the poly(vinyl alcohol)/hyaluronic acid (PVA/HA) cryogels were studied in a pH interval of 2-7.4. A significant change in properties was found at pH 5.5 specific for treatment of affected skin in psoriasis disease. [ABSTRACT FROM AUTHOR]

Hybrid hydrogels of collagen and poly (N-isopropyl acrylamide) (pNIPAM), various nanoclays and hydroxyapatite, were prepared by chemical cross-linking. These bioartificial polymeric materials were studied to establish the influence of collagen, pNIPAM, cross-linking agent and inorganic nanoparticles content on the thermal properties and heat induced denaturation in hydrated state by differential scanning calorimetry. It was established that the denaturation of collagen is an irreversible kinetic process that is governed by the temperature history, nanoparticle type in hybrid hydrogels, specimen hydration, and cross-linking agent amount, amongst other variables. The interaction of water with hybrid collagen and water state in semi-interpenetrated polymer network depends on hydrogel composition and thermal history. The hybrid hydrogels keep the temperature responsiveness. Contact angle and swelling measurements demonstrated the correlation between hydrophobicity/hydrophilicity balance and state of water in the polymer network and the denaturation temperature values. [ABSTRACT FROM AUTHOR]

Valorization of renewable biomass forestry gains more and more interest due to the exhaustible nature of fossil based resources and their negative environment impact. Therefore, this study involves thoroughly characterization of bark, needles and cones from silver fir (Abies alba Mill.) of two different ages (40 and 100 years) to determine their potential use as source of valuable compounds. Proximate/ultimate and compositional analysis as well as thermal behavior showed that the studied materials are promising candidates for biomass valorization by torrefaction and pyrolysis. In addition, it was revealed that fir samples contain significant amounts of phenolic and flavonoid compounds. The extractive fractions were found to be rich in highly valuable compounds such as terpenes, paraffins, phenols, acids and derivatives of abietic acid. This induced good antioxidant activity of the extractive fractions, with fast scavenging of DPPH radicals. The PCA and hierarchical clustering used for exploratory data analysis offered the possibility to combine multiple information obtained from detailed characterization of samples into a global view of the system. This allowed us to observe and distinguish similarities and differences among samples according to source and age. Needles stand out from bark and cones due to the high content of terpenes in extractives. Paraffins were the main components in the extractives from cones. Saccharides were found, in small amounts, only in the extractives of bark. Differences by age were also observed. The resulted outcomes provide a promising starting point in selecting suitable sources and procedures for valorization of renewable biomass forestry into energy and value added materials. • Bark, needles and cones of silver fir were thoroughly characterized and discussed • Composition and thermal behavior show suitability for thermal processes • Complex composition of extractives found by GC-MSD explain the antioxidant activity • PCA show differentiation with source (bark, needles, cones) and age (40, 100 years) [ABSTRACT FROM AUTHOR]

Semi-interpenetrated networks wereobtained by free radical polymerization/cross-linkingof substituted anhydride modified collagen with 2-hydroxyethyl methacrylate(HEMA) in the presence of ammonium persulfate (APS) and N,N,N′,N′-tetramethyl ethylene diamine (TEMED). Substituted anhydridemodified collagens, porous materials with vinyl groups, have beenpreviously synthesized by reaction of soluble collagen with dimethylmaleic anhydride (DMA) or citraconic anhydride (CTA). The structureand physicochemical properties of the obtained hydrogels were investigatedby Fourier transform infrared spectroscopy, scanning electron microscopy(SEM), and water retention studies. Thermal properties of substitutedanhydride modified collagen and their corresponding hydrogels havebeen investigated by differential scanning calorimetry (DSC) in driedand hydrated states. The denaturation temperature (Td), denaturation enthalpy, and glass transition temperature(Tg) have been determined, and they werefound to be dependent on chemical composition, thermal history, andmoisture content. The water states (free or bonded) in the hydratedsamples were correlated with their swelling degree. [ABSTRACT FROM AUTHOR]

Porous modified collagens with vinylgroups were synthesized byreaction with 2,3-dimethylmaleic anhydride or citraconic anhydride.The structure of modified collagen was assessed by analytical determinationof the amino groups in collagen and spectroscopic methods (Fouriertransform infrared (FT-IR) and proton nuclear magnetic resonance (1H NMR)). The amount of protonated amino groups and carboxylicacid moieties of the samples have been determined by potentiometrictitration. The dependence of the viscosity of diluted collagen solutionson the concentration and temperature was followed to determine theirdenaturation transitions. The increased average molecular weight,particle size, and second virial coefficient of modified collagensolutions with respect to the unmodified one proved that modificationtook place. Coupled thermal analyses (TG/DTG/DTA/FT-IR/MS) also indicatedthe collagen modification by increased thermal stability and new volatilecompounds formed during decomposition. The adhesion tests revealedtheir potential application in wound dressing and tissue engineering. [ABSTRACT FROM AUTHOR]

The modified release of active substances such as chlorzoxazone from matrix tablets, based on Kollidon®SR and chitosan, depends both on the drug solubility in the dissolution medium and on the matrix composition. The aim of this study is to obtain some new oral matrix tablet formulations, based on Kollidon®SR and chitosan, in order to optimize the low-dose oral bioavailability of chlorzoxazone, a non-steroidal anti-inflammatory drug of class II Biopharmaceutical Classification System. Nine types of chlorzoxazone matrix tablets were obtained using the direct compression method by varying the components ratio as 1:1, 1:2, and 1:3 chlorzoxazone/excipients, 20–40 w/w % Kollidon®SR, 3–7 w/w % chitosan while the auxiliary substances: Aerosil® 1 w/w %, magnesium stearate 0.5 w/w % and Avicel® up to 100 w/w % were kept in constant concentrations. Pharmaco-technical characterization of the tablets included the analysis of flowability and compressibility properties (flow time, friction coefficient, angle of repose, Hausner ratio, and Carr index), and pharmaco-chemical characteristics (such as mass and dose uniformity, thickness, diameter, mechanical strength, friability, softening degree, and in vitro release profiles). Based on the obtained results, only three matrix tablet formulations (F1b, F2b, and F3b, containing 30 w/w % KOL and 5 w/w % CHT, were selected and further tested. These formulations were studied in detail by Fourier-transform infrared spectrometry, X-ray diffraction, thermogravimetry, and differential scanning calorimetry. The three formulations were comparatively studied regarding the release kinetics of active substances using in vitro release testing. The results were analyzed by fitting into four representative mathematical models for the modified-release oral formulations. In vitro kinetic study revealed a complex mechanism of release occurring in two steps of drug release, the first step (0–2 h) and the second (2–36 h). Two factors were calculated to assess the release profile of chlorzoxazone: f1—the similarity factor, and f2—the factor difference. The results have shown that both Kollidon®SR and chitosan may be used as matrix-forming agents when combined with chlorzoxazone. The three formulations showed optima pharmaco-technical properties and in vitro kinetic behavior; therefore, they have tremendous potential to be used in oral pharmaceutical products for the controlled delivery of chlorzoxazone. In vitro dissolution tests revealed a faster drug release for the F2b sample. [ABSTRACT FROM AUTHOR]

Polyvinyl alcohol (PVA) is a non-toxic biosynthetic polymer. Due to the hydrophilic properties of the PVA, its utilization is an easy tool to modify the properties of materials inducing increased hydrophilicity, which can be noticed in the surface properties of the materials, such as wettability. Based on this motivation, we proposed to obtain high-performance composite materials by a facile synthetic method that involves the cross-linking process of polyvinyl alcohol (PVA) with and aldehyde-functionalized polysulfone(mPSF) precursor, prior to incorporation of modified MWCNTs with hydrophilic groups, thus ensuring a high compatibility between the polymeric and the filler components. Materials prepared in this way have been compared with those based on polyvinyl alcohol and same fillers (mMWCNTs) in order to establish the influence of the polymeric matrix on the composites properties. The amount of mMWCNTs varied in both polymeric matrices between 0.5 and 5 wt%. Fourier transformed infrared with attenuated total reflectance spectroscopy (FTIR-ATR) was employed to confirm the changes noted in the PVA, mPSF and their composites. Hemolysis degree was investigated in correlation with the material structural features. Homogenous distribution of mMWCNTs in all the composite materials has been confirmed by scanning electron microscopy. The hydrophilicity of both composite systems, estimated by the contact angle method, was influenced by the presence of the filler amount mMWCNTs in both matrices (PVA and mPSF). Our work demonstrates that mPSF/mMWCNTs and PVA/mMWCNTs composite could be used as water purification or blood-filtration materials. [ABSTRACT FROM AUTHOR]

New trends in biomedical applications of the hybrid polymeric hydrogels, obtained by combining natural polymers with synthetic ones, have been reviewed. Homopolysaccharides, heteropolysaccharides, as well as polypeptides, proteins and nucleic acids, are presented from the point of view of their ability to form hydrogels with synthetic polymers, the preparation procedures for polymeric organic hybrid hydrogels, general physico-chemical properties and main biomedical applications (i.e., tissue engineering, wound dressing, drug delivery, etc.). [ABSTRACT FROM AUTHOR]

Chitosan-gelatin cryogels with good loading capacity of hydrophobic compounds were successfully obtained by UV-induced crosslinking. Using riboflavin as photoinitiator was a suitable alternative to classical carbodiimide crosslinking in obtaining carrier matrices for bioactive hydrophobic compounds. Chitosan had a double role, acting both as a base polymer for the hydrogel network and as co-initiator in riboflavin photo-crosslinking. This co-initiator role of chitosan is due to its electron donor capacity, being well known as a Lewis base type macromolecule. The rheological behaviour of the chitosan-gelatin hydrogel precursor solutions was greatly influenced by riboflavin addition as well as by UV irradiation. As a consequence, the temperature of the sol-gel transition during cooling decreased to 25.5 °C. Compared with classical carbodiimide crosslinking, UV irradiation lead to gels with increased network stability, enhanced elastic behaviour, higher structural strength and almost total stress recovery yield (99 %), the latter indicating self-healing capacity. The cryogels manifested pH responsive swelling, this being highest at close to neutral pH of 7.4. Although hydrophilic in nature, the chitosan-gelatin cryogels crosslinked under the combined effect of riboflavin and UV exposure possess the necessary chemical functionality and morphology that allowed successful embedding of hydrophobic clove essential oil. This was loaded by immersion or fumigation and imparted antioxidant activity to the polymeric matrix. [Display omitted] [ABSTRACT FROM AUTHOR]

In the last decade, numerous innovative strategies have been used to obtain highly efficient synthetic or semi-synthetic biomaterials. Between these innovative biomaterials, hydrogels occupy a distinct place due to their superior biological and physico-chemical characteristics. Alginate is a natural linear polysaccharide with important physico-chemical and biological properties. Recently, we obtained a new hydrogel based on alginate and phytic acid with improved physico-chemical properties. In the present study, the hydrogels previously obtained were tested in terms of their biological properties and possibilities of use in the biomedical field. For this purpose, the hydrogels were loaded with norfloxacin (NRF), an antibacterial compound utilised in the treatment against Gram-negative and Gram-positive organisms. Unfortunately, NRF has low solubility and permeability. In order to provide protection against loss, but also for enhanced bioavailability, and controlled-release of norfloxacin, a drug inclusion complex with cyclodextrin was realized. The effect of complexation on the release profile was highlighted. The addition of NRF to the hydrogel matrices greatly improved the antibacterial activity of the tested compounds. The presence of CD did not affect the homogeneity of the drug distribution. Changes in the polymeric matrix structure were registered after the incorporation of the drug, which were attributed to the relaxation of the network subsequently to the penetration and diffusion of the drug solution simultaneously with the swelling process. The release of NRF from Alg_PA polymeric network has been successfully modulated by the use of CD as a host molecule. Schematic representation of the bioactive compound formation. [Display omitted] • Hydrogel based on alginate and phytic acid with improved physico-chemical properties • The hydrogels were tested in terms of possibilities of use in the biomedical field. • The loading capacity with norfloxacin or with its complex with cyclodextrin was attested. • Also, their capacity to drug-controlled release was evidenced. • The addition of norfloxacin improved the antimicrobial activity of the hydrogel. [ABSTRACT FROM AUTHOR]

Herein we present a new biomaterial based on cellulose, collagen and sodium alginate which served as a matrix for the incorporation of bioactive substances with antioxidant properties. Compared with pure cellulose hydrogels, the compressive strength and the elastic modulus of cellulose-collagen-alginate hydrogels were significantly enhanced, thus the compressive strength increased from 0.256 kPa to 6.91 kPa, while the elastic modulus increased from 0.0023 kPa to 0.115 kPa at 30% strain level. The release kinetic of all drugs through matrix components was done according to the Korsmeyer-Peppas model with a Fickian diffusion. The presence of bioactive principles, quercetin, lipoic acid and anthocyanins, gives biomaterials an antioxidant capacity on average 30% higher compared to the base matrix. The mechanical resistance, mucoadhesiveness, bioadhesiveness, release kinetic, and antioxidant capacity of active principles, recommend these biomaterials for the manufacture of transdermal drug delivery devices. [ABSTRACT FROM AUTHOR]

Smart hydrogels endowed with self-healing performance, enhanced stability and unique environmental responsiveness were prepared by interpenetrating the crosslinked poly(2-dimethylaminoethyl methacrylate) between the chains of the water-soluble maleoyl-chitosan. The influence of the ratio between the modified polysaccharide and the homopolymer upon the morphological structure and water uptake behaviour of the hydrogels was put in evidence by Scanning electron microscopy and swelling measurements in simulated body fluids. In addition, the synthesised compounds exhibited responsive properties, self-healing behaviour, and great availability like drug delivery systems. The in vitro study evidenced the dependence of the released procaine on the MAC content in the hydrogels, the release mechanism being controlled mainly by Fickian diffusion. The cytotoxicity assay on fibroblast demonstrated improved viability of cells by increasing the modified polysaccharide ratio into hydrogels. The self-repair capacity along with dual pH/thermo-responsiveness and biocompatibility of the hydrogels demonstrate their viability for various bio-applications. Unlabelled Image • Stimuli-responsive hydrogels formulated on PDMAEMA and maleoyl-chitosan were prepared. • Rheological profile confirmed the self-healing behaviour. • The unique environmental responsiveness of synthesised structures was evidenced. • The procaine release was controlled by Fickian diffusion. [ABSTRACT FROM AUTHOR]

The approach of covalent conjugation for coupling synthetic polymers with biomolecules represents an appealing strategy to produce new compounds with distinctive properties for biomedical applications. In the present study we generated hybrid gels with tunable characteristics by using hyaluronic acid (HA) and four variants of poly(itaconic anhydride- co -3,9-divinyl-2,4,8,10-tetraoxaspiro[5.5] undecane) (PITAU) copolymers, differing through the molar ratios between comonomers. The new bioconjugate compounds were realized by using a ″ grafting to ″ strategy, for further ensuring new ways for coupling of various bioactive compounds, taking into account that the grafted copolymers are dual sensitive to pH and temperature. The procedure of chemical crosslinking, by opening the anhydride cycle of the copolymer with the hydroxyl groups of hyaluronic acid, was used to prepare the bioconjugates. The chemical conjugation between HA and PITAU copolymers, as well as the structure of the new compounds, was confirmed by FTIR and NMR techniques. The physical properties of the new gels as thermal stability, swelling capacity, and rheological properties were investigated. The bioconjugate networks were also investigated as drug delivery carriers by using indomethacin as a model drug. In vitro and in vivo tests attested the homogeneity of the bioactive compounds as well as a good biochemical response, showing good biocompatibility for the new structures. [ABSTRACT FROM AUTHOR]

The antifungal, antibacterial, and antioxidant activity of four commercial essential oils (EOs) (thyme, clove, rosemary, and tea tree) from Romanian production were studied in order to assess them as bioactive compounds for active food packaging applications. The chemical composition of the oils was determined with the Folin-Ciocâlteu method and gas chromatography coupled with mass spectrometry and flame ionization detectors, and it was found that they respect the AFNOR/ISO standard limits. The EOs were tested against three food spoilage fungi-Fusarium graminearum, Penicillium corylophilum, and Aspergillus brasiliensis-and three potential pathogenic food bacteria-Staphylococcus aureus, Escherichia coli, and Listeria monocytogenes-using the disc diffusion method. It was found that the EOs of thyme, clove, and tea tree can be used as antimicrobial agents against the tested fungi and bacteria, thyme having the highest inhibitory effect. Concerning antioxidant activity determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis 3-ethylbenzthiazoline-6-sulfonic acid (ABTS) methods, it has been established that the clove oil exhibits the highest activity because of its high phenolic content. Promising results were obtained by their incorporation into chitosan emulsions and films, which show potential for food packaging. Therefore, these essential oils could be suitable alternatives to chemical additives, satisfying the consumer demand for naturally preserved food products ensuring its safety. [ABSTRACT FROM AUTHOR]

The present study aims to confer antimicrobial properties to PVA/PEBSA cryogels synthesized by the freeze-thaw method. The effect of thymol content on the properties and structure of the cryogel was put into evidence by Fourier Transform Infrared Spectroscopy (FT-IR), thermogravimetric analysis (TGA and DTG), and scanning electron microscopy (SEM). The influence of the conditions of antibacterial hydrogels preparation on the release profiles of thymol from the polymeric cryogels in physiological environment was put into evidence. Additionally, the antimicrobial activity of PVA/PEBSA_Thy cryogel was investigated against three different reference strains: Gram-positive bacterial strain (Staphylococcus aureus ATCC25923), fungal strain (Candida albicans ATCC10231), and Gram-negative bacterial strain (Escherichia coli ATCC25922). [Display omitted] • Preparation of a new cryogel based on PVA and poly(ethylene brassylate- co -squaric acid). • Antimicrobial properties to the new cryogels by entrapment of the bioactive substances (thymol). • The new antibacterial cryogels developed in the present work are suitable materials for wound dressing applications. [ABSTRACT FROM AUTHOR]

Abstract: With the aim of develop new materials for active food packaging, composites of low-density polyethylene (LDPE) with chitosan (CS) or chitosan sodium montmorillonite clay nanocomposites (CSnano), with or without Irganox 1076 commercial synthetic antioxidant or vitamin E (VE) as natural antioxidant were prepared by melt processing. The obtained materials have been characterized by processing behavior, mechanical and thermal properties, positive groups determination, atomic force microscopy and standard tests to assess antimicrobial and antioxidant activities. The compositions assuring insignificant decrease in mechanical and thermal properties were selected as LDPE/3CSnano/VE and LDPE/6CSnano/VE. It has been shown the chitosan imparts antimicrobial properties to LDPE films while the vitamin E increased the oxidation induction period, especially for materials containing chitosan nanocomposites. The incorporation of both chitosan nanocomposites and vitamin E in polyethylene gave films with good antimicrobial and thermal properties because of significant increase of charge surface and important changes in surface topology and antimicrobial activity because of a synergistic effect. The nanocomposites cannot only passively protect the food against environmental factors, but they may enhance shelf life of food products. [Copyright &y& Elsevier]

This study was focused on the synthesis and characterization of some ion exchange resins based on acrylic copolymers, and the composite formation by CaCO 3 by carbonate diffusion protocol. The resins were deeply investigated in terms of chemical composition (anionic, cationic, amphoteric) and crosslinker content, by: swelling degree, ion-exchange capacity, volume variation, charge density, size. FTIR-ATR spectroscopy demonstrated the presence of the functional group in the acrylic copolymers, with the formation of functionalized acrylic ion exchange resins. The materials surface morphology was evidenced using scanning electron microscopy. X-ray diffraction showed that CaCO 3 polymorphism depends on the chemical structure of the used ionic exchange resins. Some of the obtained resins and their composites with CaCO 3 were tested as sorbents for small organic molecules, such as dyes (neutral red, NR and bromocresol green, BCG) and antibiotics (tetracycline hydrochloride, TCH). While the maximum sorption capacity for BCG and NR dyes is similar (2.247 mg/g and 2.288 mg/g, respectively), but depends on the sorbent's functional groups, all the investigated samples showed a significantly higher sorption capacity for TCH, up to 50.25 mg/g. The maximum TCH release profile was improved by CaCO 3 crystallization, suggesting that the composite samples could efficiently be used as drug delivering systems. The design the resins properties by varying the precursor crosslinker content (3 and 8%) and applying a broad range of functionalization pathways was followed, by introducing weak acid, weak amino (aminolysis with ethylenediamine, triethylenetetramine or 4-dimethylaminobenzaldehyde) or zwitterionic groups. The synthesis of CaCO 3 composite materials was also followed, applying an in-situ crystallization method, based on the ammonium diffusion in desiccator. The capacity of the synthesized resins to interact with different small organic molecules, such as dyes or antibiotics, was also shown. [Display omitted] • Design the resins properties by varying the precursor crosslinker content 3 and 8%. • Ion exchanger copolymers with weak acid, weak amino or zwitterionic groups. • Synthesis of CaCO 3 composite materials by in-situ diffusion crystallization method. • The ion exchanger beads capacity to interact with different dyes or antibiotics. [ABSTRACT FROM AUTHOR]

Composites based on ethylene–propylene–diene terpolymer (EPDM), butyl/halobutyl rubber and nanosilica were prepared by melt mixing and subjected to different doses of electron beam irradiation. The effect of irradiation dose on the mechanical properties, morphology, glass transition temperature, thermal stability and water uptake was investigated. The efficiency of the crosslinking by electron beam irradiation was analyzed by Charlesby–Pinner parameter evaluation and crosslink density measurements. The scanning electron microscopy data showed a good dispersion of nanosilica in the rubber matrix. An improvement in hardness and 100% modulus was revealed by increasing irradiation dose up to 150 kGy. The interaction between polymer matrix and nanosilica was analyzed using the Kraus equation. Additionally, these results indicated that the mechanical properties, surface characteristics, and water uptake were dependent on crosslink characteristics. [ABSTRACT FROM AUTHOR]

Here we present a new biomaterial based on cellulose, collagen and polyurethane, obtained by dissolving in butyl imidazole chloride. This material served as a matrix for the incorporation of tannin and lipoic acid, as well as bioactive substances with antioxidant properties. The introduction of these bioactive principles into the base matrix led to an increase of the compressive strength in the range 105–139 kPa. An increase of 29.85% of the mucoadhesiveness of the film containing tannin, as compared to the reference, prolongs the bioavailability of the active substance; a fact also demonstrated by the controlled release studies. The presence of bioactive principles, as well as tannins and lipoic acid, gives biomaterials an antioxidant capacity on average 40%–50% higher compared to the base matrix. The results of the tests of the mechanical resistance, mucoadhesiveness, bioadhesiveness, water absorption and antioxidant capacity of active principles recommend these biomaterials for the manufacture of cosmetic masks or patches. [ABSTRACT FROM AUTHOR]

The purpose of the present study is to develop new multifunctional environmentally friendly materials having applications both in medical and food packaging fields. New poly(lactic acid) (PLA)-based multifunctional materials containing additives derived from natural resources like chitosan (CS) and rosemary extract (R) were obtained by melt mixing. Each of the selected components has its own specific properties such as: PLA is a biodegradable thermoplastic aliphatic polyester derived from renewable biomass, heat-resistant, with mechanical properties close to those of polystyrene and polyethylene terephthalate, and CS offers good antimicrobial activity and biological functions, while R significantly improves antioxidative action necessary in all applications. A synergy of their combination, an optimum choice of their ratio, and processing parameters led to high performance antimicrobial/antioxidant/biocompatible/environmentally degradable materials. The polyethylene glycol (PEG)-plasticized PLA/chitosan/powdered rosemary extract biocomposites of various compositions were characterized in respect to their mechanical and rheological properties, structure by spectroscopy, antioxidant and antimicrobial activities, and in vitro and in vivo biocompatibility. Scanning electron microscopy images evidence the morphology features added by rosemary powder presence in polymeric materials. Incorporation of additives improved elongation at break, antibacterial and antioxidant activity and also biocompatibility. Migration of bioactive components into D1 simulant is slower for PEG-plasticized PLA containing 6 wt % chitosan and 0.5 wt % rosemary extract (PLA/PEG/6CS/0.5 R) biocomposite and it occurred by a diffusion-controlled mechanism. The biocomposites show high hydrophilicity and good in vitro and in vivo biocompatibility. No hematological, biochemical and immunological modifications are induced by subcutaneous implantation of biocomposites. All characteristics of the PEG-plasticized PLA-based biocomposites recommend them as valuable materials for biomedical implants, and as well as for the design of innovative drug delivery systems. Also, the developed biocomposites could be a potential nature-derived active packaging with controlled release of antimicrobial/antioxidant compounds. [ABSTRACT FROM AUTHOR]

The effects of electron beam irradiation on the properties of ethylene propylene diene monomer (EPDM)/butyl rubber composites in presence of a polyfunctional monomer were investigated by means of differential scanning calorimetry (DSC), thermal analysis, scanning electron microscopy (SEM), attenuated total reflection absorption infrared spectroscopy (ATR-IR), and mechanical and surface energy measurements. The samples were exposed over a wide range of irradiation doses (20–150 kGy). The EPDM matrix was modified with butyl rubber, chlorobutyl rubber, and bromobutyl rubber. The gel content and crosslink density were found to increase with the electron beam irradiation dose. The values of the hardness and modulus increased gradually with the irradiation dose, while the tensile strength and elongation at break decreased with increasing irradiation dose. The EPDM/butyl rubber composites presented a higher thermal stability compared to the initial EPDM sample. The incorporation of butyl rubbers into the EPDM matrix led to an increase in material hydrophobicity. A similar trend was observed when the irradiation dose increased. The greatest change in the surface free energy and the contact angles occurs at an irradiation dose of 20 kGy. The Charlesby–Pinner plots prove the tendency to crosslinking as the irradiation dose increases. [ABSTRACT FROM AUTHOR]

New multifunctional materials containing additives derived from natural resources as powdered rosemary ethanolic extract were obtained by melt mixing and processed in good conditions without degradation and loss of additives. Incorporation of powdered rosemary ethanolic extract (R) into poly(lactic acid) (PLA) improved elongation at break, rheological properties, antibacterial and antioxidant activities, in addition to the biocompatibility. The good accordance between results of the chemiluminescence method and radical scavenging activity determination by chemical method evidenced the increased thermoxidative stability of the PLA biocomposites with respect to neat PLA, with R acting as an antioxidant. PLA/R biocomposites also showed low permeability to gases and migration rates of the bioactive compounds and could be considered as high-performance materials for food packaging. In vitro biocompatibility based on the determination of surface properties demonstrated a good hydrophilicity, better spreading and division of fibroblasts, and increased platelet cohesion. The implantation of PLA/R pellets, was proven to possess a good in vivo biocompatibility, and resulted in similar changes in blood parameters and biochemical responses with the control group, suggesting that these PLA-based materials demonstrate very desirable properties as potential biomaterials, useful in human medicine for tissue engineering, wound management, orthopedic devices, scaffolds, drug delivery systems, etc. Therefore, PLA/R-based materials show promising properties for applications both in food packaging and as bioactive biomaterials. [ABSTRACT FROM AUTHOR]