Preparation,characterization, antibacterial properties,and hemostatic evaluation of ibuprofen‐loaded chitosan/gelatin composite films

Ibuprofen‐loaded chitosan/gelatin (CS/GE) composite films were fabricated in this work. The morphology of the composite film was investigated using scanning electron microscopy. The functional groups of the composite film before and after crosslinking were characterized using Fourier transform infrared spectroscopy. Meanwhile, the mechanical properties, antibacterial performance, cytocompatibility, and hemostatic activity of the composite films were investigated. The results show that the amount of CS affected the mechanical properties and liquid uptake capacities of the composite films. The composite film showed better bactericidal activity against Staphylococcus aureus than Escherichia coli. In vitro drug‐release evaluations showed that crosslinking could control the drug‐release rate and period in wound healing. Both types of CS/GE and drug‐loaded CS/GE composite films also showed excellent cytocompatibility in cytotoxicity assays. The hemostatic evaluation indicated that the composite film crosslinked by glutaraldehyde in rabbit livers had a dramatic hemostatic efficacy. Therefore, ibuprofen‐loaded CS/GE composite films are potentially applicable as a wound dressing material. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45441.     

Rapid synthesis of high strength cellulose–poly(vinyl alcohol) (PVA) biocompatible composite films via microwave crosslinking

The present study describes microwave (MW)-assisted rapid synthesis of biocompatible poly(vinyl alcohol) (PVA) composite films that demonstrate synergy between reinforcement and crosslinking. Bacterial cellulose (5% w/w) nanowhiskers (reinforcement) and tartaric acid 35% (w/w) (crosslinker) are incorporated in PVA to prepare crosslinked cellulose–PVA composite films. The properties of thus prepared crosslinked cellulose–PVA composite films are compared with samples crosslinked with conventional hot air oven heating (CH). Crosslinking by both of the methods reduces water absorption of PVA by around an order of magnitude and improves its thermal stability. An increase in strength from 42 (PVA) to 172 MPa and 159 MPa for MW and CH crosslinked samples, respectively is also observed. Although composites prepared using MW and CH show similar properties, MW takes only 14 min compared to 2 h in case of CH. Notably, the prepared composites demonstrate hemocompatibility and cytocompatibility, and may also be explored for biomedical applications. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47393.     

Characteristics of poly(vinyl alcohol) films crosslinked by cinnamaldehyde with improved transparency and water resistance

Poly(vinyl alcohol) (PVA) films crosslinked by cinnamaldehyde (CIN) at various concentrations were prepared. Their physicochemical and antibacterial properties were compared with those of uncrosslinked films. The results suggest that the crosslinked films exhibited higher transparency, tensile strength, and elongation at break in a certain CIN concentration range. They also displayed decreased water vapor permeability and water solubility. Although the antibacterial activity of the crosslinked film‐forming solution was less slightly than that of the uncrosslinked film‐forming solution, the crosslinked film‐forming solution still demonstrated strong antibacterial activity when the concentration of CIN was 2% v/v. The aldol condensation reaction between the aldehyde group of CIN and the alcoholic hydroxyl group of PVA was determined by Fourier transform infrared spectroscopy. By the crosslinking reaction, the heat stability of the crosslinked film was enhanced compared with that of the uncrosslinked film. Meanwhile, a compact, smooth, and continuous cross‐sectional microstructure present in the crosslinked film was observed by scanning electron microscopy. The higher water resistance and transparency gave the crosslinked films priority for use in food packaging. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45324.     

Properties of chitosan/poly(vinyl alcohol) films for drug‐controlled release

With bovine serum albumin (BSA) as a model drug, drug‐loaded films of chitosan (CS) and poly(vinyl alcohol) (PVA) were obtained by a casting/solvent evaporation method and crosslinked by tripolyphosphate (TPP). The films were characterized by FTIR, XRD, and SEM. The influential factors of drug‐loaded films on drug‐controlled release were studied. These factors included, primarily, the component ratio of CS and PVA, the loaded amount of BSA, the pH and ionic strength of the release solution, and the crosslinking time with TPP. The results showed that within 25 h, when the weight ratios of CS to PVA in the drug‐loaded films were 90 : 10, 70 : 30, 50 : 50, and 30 : 50, the cumulative release rates of BSA were 63.3, 72.9, 81.8, and 91.8%, respectively; when the amounts of model drug were 0.1, 0.2, and 0.3 g, the release rates were 100, 81.8, and 59.6%, respectively; when the pH values of the drug release medium were 1.0, 3.8, 5.4, and 7.4, the release rates reached 100, 100, 37.9, and 7.8%, respectively; the cumulative release rates of BSA were 78.4, 82.3, 84.3, and 91.7% when the ionic strengths of the release solution were, respectively, 0.1, 0.2, 0.3, and 0.4M; when the crosslinking times of these drug films in the TPP solution were 0, 5, 15, 30, and 60 min, the release rates attained 100, 100, 81.8, 65, and 43.3%, respectively. All the results indicated that the CS/PVA film was useful in drug delivery systems. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 808–813, 2005     

Development of active cassava starch films reinforced with waste from industrial wine production and enriched with pink pepper extract

This study investigated the influence of grape stalk (GS) from the Bordo grape variety (Vittis labrusca L.) as a reinforcing agent, and pink pepper (Schinus terebinthifolius Raddi) extract (PPE) as an antioxidant, in cassava starch (CS)-glycerol (GLY) films. The developed biodegradable films were characterized according to structural, barrier, mechanical, antioxidant and optical properties, as well as biodegradability and compared to both the control and blank films. Films containing a high GS content exhibited a significant increase in tensile strength (TS) values by 73%, whereas the films containing a high PPE content exhibited an important increase elongation (ELO) values by 20%, comparing to the control film (CO). The films containing 5.52% v/v of PPE presented an improving on antioxidant activity and barrier properties, leading DPPH and ABTS percentual radical scavenging activity by 51.79% and 58.18%, and decreasing water vapor permeability and solubility by expressive values of 34.11% and 79.43%, respectively. According to the results obtained in this study, the films using GS and PPE exhibited valuable characteristics and are an alternative for applications as a promising biodegradable packaging material.     

Graphene oxide–polyoctahedral silsesquioxane–chitosan composite films with improved mechanical and water-vapor-transport properties

Graphene oxide (GO) and ball-milled maleamic acid–isobutyl polyoctahedral silsesquioxanes (MAIPSs) were incorporated simultaneously into chitosan (CS) via solution blending to evaluate their combined effects on the structures and properties of composite films. GO and MAIPS aggregates were homogeneously dispersed in CS and affected the crystallinities of the composite films. The binary addition of GO and MAIPS resulted in synergistic enhancements of the tensile strength and elongation at break of the composite films. Composite films containing 3% w/w MAIPS and 0.25% w/w GO (CS–GO–MAIPS-3) exhibited the highest strength and modulus, which were 48 and 42.2% higher, respectively, than the values of the CS film. The water-vapor-sorption isotherms revealed that monolayer sorption sites decreased with the addition of GO or/and MAIPS, but the dissolution process was not significantly influenced. The water-vapor permeability reached its lowest value for the CS–GO–MAIPS-3 film because of hindered diffusion with the presence of impermeable nanoparticles. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47748.     

Barrier properties and abrasion resistance of biopolymer‐based coatings on biodegradable poly(lactic acid) films

Coated polylactic acid (PLA) films consisting of crosslinked‐chitosan/beeswax layer were prepared to improve barrier properties and abrasion resistance of the base substrate. The effect of crosslinking the chitosan layer on durability and barrier properties of the coatings was investigated. Crosslinked samples exhibited lower degree of swelling compared to uncrosslinked samples and 50% reduction in water vapor transmission rate (WVTR) compared to neat PLA films. The beeswax coating decreased the WVTR of chitosan‐coated PLA films significantly (by 100%). However, it had a marginal effect on the oxygen transmission rate. Water vapor transmission was less affected by abrasion than oxygen transmission for both uncrosslinked and crosslinked samples. The WVTR of crosslinked samples were retained even after being subjected to abrasion, whereas WVTR of uncrosslinked samples dropped by 50%. Results obtained using the Taber test method also show that the weight loss of crosslinked coatings are about 75% less than that of uncrosslinked samples and can withstand a greater number of cycles before rupture. These translucent‐coated films retained good barrier and mechanical properties along with providing improved abrasion resistance after crosslinking. This approach provides exciting new possibilities for expanding the use of biodegradable polymers in packaging applications. POLYM. ENG. SCI., 59:1874–1881, 2019. © 2019 Society of Plastics Engineers     

Tensile,Swelling, and Oxidative Degradation Properties of Crosslinked Polyvinyl Alcohol/Chitosan/Halloysite Nanotube Composites

Glutaraldehyde (GA) crosslinked polyvinyl alcohol (PVA)/chitosan (CS)/halloysite nanotube (HNT) composite films were prepared using a wet casting method. The tensile, morphology, thermal degradation, swelling, moisture, and oxidative degradation properties of crosslinked composite films were carried out. The presences of crosslinking in the composite films were confirmed by FTIR result. The tensile strength of the crosslinked composite films increased up to 0.5 wt% of HNTs loading. Increasing HNTs reduced the thermal degradation, swelling, and moisture properties of crosslinked composite films reduced with the increase of HNTs content. Results also indicated that the crosslinked composite films were degraded using Fenton reagent.     

Production and characterization of chitosan microparticles containing papain for controlled release applications

The production and modification of chitosan microparticles using crosslinking agents and papain were evaluated for controlled release applications. Chitosan microparticles were produced and crosslinked with sodium tripolyphosphate (TPP) 10% (w/v) solution or glutaraldehyde (GLU) 0.75% (w/w), with subsequent papain sorption. Microparticles were characterized by Fourier transformed infrared spectroscopy (FTIR) for chemical modifications, scanning electron microscopy (SEM) for morphology and X-ray diffraction (XRD) for crystallographic analysis. Chemical composition and the thermal stability of the material were characterized by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). It was observed that the presence of TPP and papain resulted in a decrease of the stability of the chitosan matrix. Papain release rates from the microparticles were also conducted in vitro. The amount of released papain in phosphate buffer (pH = 7.4) was analyzed with UV-spectroscopy, showing release profiles of enzymatic activity ranging from 0.006 to 0.011 μmol.min^? 1. The results indicate that both chitosan–TPP–papain and chitosan–GLU–papain microparticles can successfully be used for systems that aim at a controlled release of papain with potential use in the biomedical area.     

Influence of crosslinking methods toward poly(vinyl alcohol) properties: Microwave irradiation and conventional heating

In this study, crosslinking of poly(vinyl alcohol) (PVA) with tartaric acid, as crosslinker, is performed using microwave irradiation. A comparison between the properties of PVA crosslinked using microwave irradiation and conventional heating methods is also discussed. While the water absorption, tensile and thermal properties of PVA crosslinked by either of the methods are comparable, microwave irradiation took only one‐eighth (14 min) of the time compared to conventional heating. In comparison with PVA (42 MPa), the strength of PVA crosslinked with 35% TA increased to 145 and 153 MPa for conventional heating and microwave irradiation, respectively. Water absorption of crosslinked PVA film is successively reduced to less than 30% in comparison with PVA (～200%). Moreover, the crosslinked films are stable at higher temperatures in comparison with PVA. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46125.     

Bio‐nanocomposite films based on cellulose nanocrystals filled polyvinyl alcohol/chitosan polymer blend

Bio‐nanocomposite films based on polyvinyl alcohol/chitosan (PVA/CS) polymeric blend and cellulose nanocrystals (CNC) were prepared by casting a homogenous and stable aqueous mixture of the three components. CNC used as nanoreinforcing agents were extracted at the nanometric scale from sugarcane bagasse via sulfuric acid hydrolysis; then they were characterized and successfully dispersed into a PVA/CS (50/50, w/w) blend to produce PVA/CS–CNC bio‐nanocomposite films at different CNC contents (0.5, 2.5, 5 wt %). Viscosity measurement of the film‐forming solutions and structural and morphological characterizations of the solid films showed that the CNC are well dispersed into PVA/CS blend forming strong interfacial interactions that provide an enhanced load transfer between polymer chains and CNC, thus improving their properties. The obtained bio‐nanocomposite films are mechanically strong and exhibit improved thermal properties. The addition of 5 wt % CNC within a PVA/CS blend increased the Young's modulus by 105%, the tensile strength by 77%, and the toughness by 68%. Herein, the utilization of Moroccan sugarcane bagasse as raw material to produce high quality CNC has been explored. Additionally, the ability of the as‐isolated CNC to reinforce polymer blends was studied, resulting in the production of the aforementioned bio‐nanocomposite films with improved properties. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42004.     

Taguchi orthogonal array design for the optimization of hydrogel nanoparticles for the intravenous delivery of small‐molecule drugs

In this study, a 16 runs Taguchi method was applied as an experimental design to establish the optimum conditions for hydrogel nanoparticle preparation. Five relevant factors, chitosan (CS) concentration, pentasodium tripolyphosphate (TPP) concentration, CS‐to‐TPP volume ratio, addition time of the TPP solution to the CS solution, and temperature, were selected as the main determinants, and the effects of each factor on the size of the hydrogel nanoparticles were studied at four levels. The statistical analysis revealed that the most important factors contributing to the achievement of minimum particle size were the CS‐to‐TPP volume ratio and the CS concentration. By solving a set of equations derived from the differentiation of the final model, we established the optimum conditions for hydrogel nanoparticle preparation as follows: CS concentration = 0.28% w/v, TPP concentration = 3.17% w/v, TPP/CS = 1 : 8, temperature = 25.66°C, and addition time of the TPP solution to the CS solution = 0.4 min. Also, an analysis of response at the different levels of the factors indicated that there was no remarkable interaction between them. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2012     

Antioxidant,antifungal, water binding,and mechanical properties of poly(vinyl alcohol) film incorporated with essential oil as a potential wound dressing material

In this study, the properties of poly (vinyl alcohol) (PVA) films incorporated with Zataria multiflora essential oil (ZMO) as a potential antioxidant/antibacterial material was investigated. PVA films were prepared from PVA solutions (2% w/v) containing different concentrations of ZMO. Water solubility, moisture absorption, water swelling, and water vapor permeability for pure PVA films were 57 ± 1.1, 99 ± 3.2%, 337 ± 8%, and 0.453 ± 0.015 g mm/m² h, respectively. Incorporation of ZMO into PVA films caused a significant decrease in water swelling and moisture absorption and increase in solubility and water vapor permeability. Tensile strength, elastic modulus, and elongation at break for pure PVA films were 13.5 ± 0.61 MPa, 15.2 ± 0.8 MPa, and 216 ± 4%, respectively. Incorporation of ZMO into the PVA films caused a significant decrease in tensile strength and elastic modulus and increase in elongation at break of the films. Pure PVA film showed UV‐visible light absorbance ranging from 280 to 440 nm with maximum absorbance at 320 nm. Addition of ZMO caused a significant increase in light absorbance and opacity. PVA films exhibited no antioxidant and antifungal activities, whereas PVA/ZMO films exhibited excellent antioxidant and antifungal properties. Although the bioactivity PVA films were improved by the addition of ZMO, however, the mechanical properties and water binding capacity of the films were weaken slightly. Thus, ZMO emulsified in the ethanol not compatible with PVA matrix and more suitable emulsifier was needed in order to obtain strong film with higher mechanical properties. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40937.     

Gallic acid crosslinked peanut protein-corn starch composite edible films produced at alkaline pH with ultrasound application

Corn starch and peanut protein blend films were prepared with and without gallic acid addition (0.25%, w/v) at pH 7, 9, and 11 by casting. The ultrasound (160 W, 20 kHz, 10 min) treatment was applied to the film-forming solutions. This study aimed to develop biopolymer-based films with gallic acid and to determine the interactions of components at different pHs and with ultrasound. The barrier, optical, mechanical, and thermal properties of films were examined. Moreover, structural characterization of films was conducted by Fourier transform infrared (FTIR), x-ray diffraction, and trinitro benzenesulfonic acid assay to enlighten the crosslinking interactions of gallic acid with biopolymers at different pHs. At neutral pH, gallic acid behaved as plasticizer. By acting as a crosslinker at pH 9, gallic acid provided the lowest moisture content, darker and more opaque appearance, enhanced barrier performance and thermal stability. The crosslinking degrees of gallic acid-enriched films were 49.1% (pH 7), 77% (pH 9), and 67.4% (pH 11). Additionally, gallic acid increased antioxidant capacity. The ultrasonication adversely affected the film properties by breaking bonds in the film structure. Peanut protein-corn starch-gallic acid films under mild alkaline conditions exhibited outstanding thermal stability, mechanical durability, light, and water barrier characteristics, making them appropriate for sustainable food packaging applications.     

Thermal properties of proton-conducting radiation-grafted membranes

Proton-exchange membranes are required to exhibit chemical, mechanical, and thermal stability for fuel cell applications. The present investigation has been carried out to explore the thermal behavior of poly(ethylene-alt-tetrafluoroethylene) (ETFE)-based proton-conducting membranes, both uncrosslinked and crosslinked, prepared by radiation grafting and subsequent sulfonation. The influence of preparation steps (irradiation, grafting, sulfonation, crosslinking) on the thermal degradation, crystallinity, and melting behavior of membranes with varying degree of grafting was examined. ETFE base film and grafted films were studied as the reference materials. Furthermore, poly(tetrafluoroethylene-co-hexafluoropropylene)-based grafted films and membranes were investigated as well for comparison. Membrane preparation steps, degree of grafting, crosslinking, type of base polymer have considerable influence on the thermal properties of membranes. The crystallinity of the films decreases slightly by grafting, while a significant decrease was observed after sulfonation. For instance, crystallinity decreased from 37% (pristine ETFE) to 36% (uncrosslinked grafted film) and 23% (uncrosslinked ETFE-based membrane). On the other hand, the melting temperature of the base polymer was almost unaffected by irradiation and grafting. The crosslinked ETFE-based membranes exhibit a slightly higher melting temperature (262.5°C) than their corresponding grafted films (261.3°C) and the base film (260.6°C). © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Effects of Conjugation between Proteins and Polysaccharides on the Physical Properties of Emulsion-Based Edible Films

The effects of conjugation between protein (soybean or peanut protein isolates) and polysaccharides (dextran or gum acacia) with different glycation time (0–32 hours) on the physical properties of emulsion-based edible films containing beeswax as dispersed phase were studied. Both the reaction time and type of polymers significantly (P < 0.05) affected the emulsifying properties of conjugates. Pearson's correlation analysis showed that the emulsifying activity index (EAI), emulsifying stability index (ESI), and droplet size of emulsions were in strong correlation with the physical properties of films, such as whiteness index, transparency, water vapor permeability, surface hydrophobicity, thermal stability, and mechanical properties. Furthermore, even though glycation could significantly (P < 0.05) affect intermolecular interactions between polymers in films, there was no strong correlation between the intermolecular interactions and the physical properties of films. Therefore, the emulsifying properties of conjugates are essential for preparing emulsion-based edible films.     

壳聚糖及壳聚糖-羧甲基纤维素钠复合囊材的体外降解性能研究

制备了CS膜、交联CS膜、交联CS／CMCNa双层、多层复合膜以及ECH交联多层复合膜,考察了交联cs膜在不同介质中的降解,比较了上述几种膜材料在溶菌酶PBS溶液中的降解情况,对不同囊材载药微囊进行了体外降解实验。结果表明,交联cs膜在溶菌酶PBS溶液中降解速率最大。膜材料在溶菌酶PBS溶液中的降解速率与交联程度有关,载药微囊可以被溶菌酶降解。     

Tensile properties,barrier properties,and biodegradation in soil of compression—Molded gelatin‐dialdehyde starch films

Glycerol (Gly)‐plasticized gelatin (Ge) films crosslinked with dialdehyde starch (DAS) as environmentally friendly crosslinking agent were successfully produced by compression molding, demonstrating the capacity of gelatin of being transformed into films by using thermoplastic processes. The effect of DAS content on the color, light transmission, total soluble matter (TSM), water uptake (WU), water vapor permeability (WVP), oxygen permeability (OP) as well as biodegradability during soil burial was investigated. The addition of up to 10 wt % DAS (Ge‐10DAS) generated transparent films, with reduced TMS, WU, WVP, and OP values but higher extensivity than the uncrosslinked counterpart. Further incorporating DAS into plasticized‐gelatin matrix conducted to phase separation with detrimental effect of transparency and tensile properties. DAS‐containing films degraded at slow rate than the uncrosslinked counterpart, suggesting that biotic attack during soil burial is restricted by covalent crosslinking points induced by DAS. Ge‐10DAS films lost about 28% of their initial mass within the first 8 days of exposure to degrading medium; therefore, the material can be classified as rapidly degradable. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

交联壳聚糖/蒙脱土复合膜的制备及性能研究

以壳聚糖（CS）为基质材料，蒙脱土（MMT）为填料，采用戊二醛（GA）交联改性并结合溶液插层法制备了交联壳聚糖/蒙脱土（CS/GA/MMT）复合膜。通过扫描电子显微镜、X射线衍射仪、红外光谱仪及热重分析仪对复合膜的结构进行了表征，考察了MMT用量对复合膜的吸水性能、水蒸气阻隔性能和力学性能的影响。结果表明，交联改性CS可提高CS膜的耐水性，CS/GA膜的吸水率较CS膜降低了9.6 %；MMT可提高复合膜的耐水性、水蒸气阻隔性能、力学性能和热稳定性；当MMT的用量为CS质量的5 %时，复合膜的各项性能较好，吸水率、水蒸气透过率和断裂伸长率较CS膜分别降低了37.3 %、36.7 %和41.9 %，且拉伸强度提高了160.5 %。     

Preparation and characterization of crosslinked and heat-treated PVA-MA films

Two kinds of water-insoluble PVA-MA hydrogel films were prepared from PVA-MA, an esterification product of poly(vinyl alcohol) and maleic anhydride, by heat treatment and a crosslinking reaction, respectively. Both films changed their dimensions upon environmental pH changes. The crosslinked gel expanded to approximately 230% of its original length, with most changes occurring in the pH range of 2–7. The heat-treated PVA-MA film swelled stepwisely, with about 45% of the total expansion occurring at pH 2–7 and the remaining 55% at pH 9–12. Results from IR spectra analysis and acid-base titration suggest that the ionization of carboxylic acid accounts for the pH-induced gel swelling irrespective of the differences in the swelling behavior of these two gels. The pK_a values of the heat-treated PVA-MA gel increased from 4 to 10 while the degree of dissociation varied from 0 to 80%, whereas that of the crosslinked PVA-MA film is limited in a range of 3.3–4.2. The permeability of glucose across the crosslinked PVA-MA film increased when pH was raised from 2 to 7. No significant change of permeability was noticed between pH 7 and 12. For the heat-treated PVA-MA film, glucose permeability increased when pH was changed from 2 to 7 and from 7 to 12. © 1996 John Wiley & Sons, Inc.