Properties Of Chitosan Films Research Articles

Functional properties of chitosan films modified by snail mucus extract

Snail mucus is an attractive natural substance, which is increasingly used in cosmetic creams and syrups thanks to its emollient, moisturizing, protective and reparative properties. The aim of the present study was to explore the physicochemical properties of chitosan-based films added with snail mucus extracted from Helix Aspersa Muller. To this aim, chitosan films at different content of snail mucus were fabricated by simple solvent casting technique. The results of X-ray diffraction analyses, tensile mechanical tests, Infrared spectroscopy and thermogravimetry demonstrated that snail mucus addition strongly modifies the properties of chitosan films. In particular, it acted like a plasticizer enhancing films extensibility up to ten times and strongly improving their water barrier and bioadhesion properties, with a trend depending on Snail mucus content. Furthermore, it provides the films with antibacterial properties and enhanced cytocompatibility, yielding materials with tailored properties for specific requirements.

Self-cleaning and antimicrobial photo-induced properties under indoor lighting irradiation of chitosan films containing Melon/TiO2 composites

Chitosan films containing visible-light absorbing melon/TiO2 composites (MTiO2) (CTS/MTiO2), prepared by sol-gel method using urea as precursor, were evaluated as self-cleaning and antimicrobial photo-induced surfaces under indoor lighting irradiation. Malachite green and staphylococcus aureus were used as model pollutant and bacteria strain respectively. Characterization revealed that MTiO2 nanoparticles were successfully incorporated on chitosan films. Presence of nanoparticles on chitosan films did not strongly affect tensile strength of films, however, its solubility was highly reduced.Dye stains on CTS/MTiO2 films were efficiently removed after 72 h of continuous indoor lighting irradiation. It was found that dye molecule underwent N-demethylation reactions caused probably by the attack of photo-induced OH radicals produced on MTiO2 surfaces while dye ATR-FT-IR spectrum exhibited the presence of CO groups probably linked to benzophenones generated by the reaction between malachite green molecules and photo-induced singlet oxygen (1O2). Furthermore, CTS/MTiO2 exhibited self-cleaning properties during 15 days of continuous indoor lighting irradiation. S. aureus underwent a culturability dropping of around 3 logs after 3 h of irradiation while chitosan and chitosan/P25 films did not exhibit culturability decreasing. Although self-cleaning properties were not altered by continuous irradiation, it was found that surface morphology and physical-chemical properties of chitosan films underwent changes.

Green Microcomposites from Renewable Resources: Effect of Seaweed (Undaria pinnatifida) as Filler on Corn Starch–Chitosan Film Properties

Natural seaweed microparticles obtained from Undaria pinnatifida waste (A) were used as fillers in thermoplastic starch (TPS)–chitosan (CH) blend in order to obtain microcomposites films for application in sustainable agriculture. The adequate proportion of both polymers was optimized with regards their mechanical, barrier, water interaction and morphological properties. Then, the effect of different content of seaweed on microcomposites properties was investigated. The seaweed used showed good interaction with the TPS–CH matrix. Its addition produced an increase in the tensile strength and a slight increase in the elongation at break. Contents of 10% of A lead to a more heterogeneous structure with the formation of aggregates. Low contents of A reduced the mobility of the polymer chains resulting in a lower moisture content and higher Tg, although the WVP increased with the content of A. The improvements achieved with microcomposites were finally discussed under the light of new agricultural mulch films regulations.

Synergistic effect of hydrophilic palygorskite and hydrophobic zein particles on the properties of chitosan films

Chitosan (CS) with unique properties can interact with hydrophilic nanoclay and hydrophobic plant protein particles. In this study, we designed a CS matrix using hydrophilic palygorskite (PAL) nanoclay and hydrophobic zein particles (ZPs) as combined fillers for reinforcement. CS–PAL–ZP ternary composites were prepared using solution casting method, and the synergistic reinforcing role of PAL and ZP on the properties of CS matrix was studied. Homogenous dispersion of the combined nanofillers in the CS matrix resulted in a remarkable enhancement in tensile strength, water resistance and surface hydrophobicity at low loadings. In addition, the tensile strength and surface hydrophobicity of CS–PAL–ZP ternary composites were higher than those of CS–PAL or CS–zein composites with the same amounts of individual filler. These results clearly confirmed the synergistic reinforcement of hydrophilic PAL and hydrophobic ZP in improving the various properties of CS-based composite. Therefore, this approach would provide an effective method for designing and fabricating ternary composites based on amphiphilic polymer matrix and hydrophilic–hydrophobic fillers with improved properties for extending their applications.

Effect of syringic acid incorporation on the physical, mechanical, structural and antibacterial properties of chitosan film for quail eggs preservation

The physical mechanics and structural properties of composite films based on chitosan and syringic acid (SA) were studied in this study. The results indicated that the addition of SA made the chitosan-SA films exhibited higher density, water solubility and opacity, but the water vapor permeability and water content were decreased. In addition, Chitosan-SA films had a significant antibacterial effect on test bacteria. The surface and cross-section of chitosan-SA films were more uniform and smoother when combined with 0.25% and 0.5% 0f SA. The FT-IR and XRD spectra of the chitosan-SA film indicated that the interaction between chitosan and SA may be non-covalent, and DSC indicated that the thermal stability of the composite film was reduced. In summary, the modified color, increased bacteriostatic and water-blocking properties, as well as the slight changes in mechanical properties indicated that the addition of SA may contribute to extend the shelf life of the food. Thus, chitosan-SA films incorporating 0.25% and 0.5% of SA can be further explored as active packing materials for food preservation. The composite film was used for the preservation of quail egg coatings, and it was found that 0.25% and 0.5% of the coating film had a good preservation effect.

Preparation of chitosan/curdlan/carboxymethyl cellulose blended film and its characterization.

In this study, to improve the thermal and mechanical properties of chitosan films, a chitosan/curdlan/carboxymethyl cellulose (CS/CD/CMC) ternary blended film was prepared and characterized. To prepare a uniform CS/CD/CMC ternary blended film, an effective method of blending CD with other materials was established as the following conditions: the ternary solution temperature was maintained at 60°C, and the pH was controlled in the range from 12 to 4. Compared to the pure chitosan, the CS/CD/CMC blended films exhibited better mechanical properties, permeability, and thermal stability. In addition, visible light properties of the ternary blending film were improved. Scanning electron microscope and Fourier transform-infrared spectroscopy analyses indicated good compatibility among the CS, CD and CMC, which led to a corresponding improvement in the properties owing to interactions among the three components in the blending process. So, an effective method of blending CD with CS and CMC was established, and the blending film has good thermal and mechanical properties.

Preparation of bioactive hydroxyapatite@halloysite and its effect on MC3T3-E1 osteogenic differentiation of chitosan film.

Halloysite nanotubes (HNTs) are widely used in biomedical field due to their special tubular structure and high reinforcing ability, while hydroxyapatite (HAP) is generally used in tissue engineering owing to its excellent biocompatibility and biological activity. In this work, hydroxyapatite@halloysite nanotubes(HAP@HNTs) hybrid was synthesized via a facial hydrothermal reaction process. The morphology, particle size, specific surface area, and chemical composition of the hybrid were thoroughly characterized by different techniques. Rod-like HAP nanoparticles can be anchored on the outer surface of the clay tubes, which lead to a maximum increase of 4.7 m2/g in the specific surface area of HAP@HNTs over that of HNTs. HAP nanoparticles have little effect on the pores of HNTs, but diffraction peak strength of HNTs is covered by the HAP crystals. HAP@HNTs exhibit improved cytocompatibility and possess osteogenic differentiation ability towards MC3T3-E1 preosteoblasts. Chitosan/HAP@HNTs composite films were then prepared by doping of HAP@HNTs into chitosan by solution mixing. HAP@HNTs can serve as a functional phase which enhances mechanical properties of chitosan films and osteogenic differentiation of MC3T3-E1 cells. This work provides a facial synthesis routine of bioactive HAP@HNTs, which combines the osteogenic activity of HAP and the good mechanical properties of HNTs. HAP@HNTs can be used a novel bone regeneration biomaterial as local delivery systems with improved osteoinductive properties.

Energy harvesting properties of chitosan film in harvesting water vapour into electrical energy

A water vapor cell (WVC) made of chitosan-based film has been successfully generated electrical energy when directly interacted with water vapor. The chitosan concentration in film was varied from 0 to 4.5%. WVC was characterized using a climate chamber oven to determine the energy harvesting properties when exposed to water vapour which represented as relative humidity (30–90% RH). No electrical energy was generated by 0% chitosan film. However, the other concentration generated electrical energy started to increase and reaching almost a steady state after 13–11 h exposure to > 70% RH. The highest electrical energy was 120.13 μW obtained by 4% chitosan film and maintained continuously under 90% RH exposure. This electrical energy generation was due to the chemical interaction of hydrogen bonding that occurs between water vapor molecules and amine groups (NH2) of chitosan film as proven by FTIR analysis. Furthermore, chitosan film morphology was also contributing to the energy harvesting ability as proven by AFM and FESEM analyses where film concentration ≤ 4.0% have a smooth surface which favored the electrical energy generation.

Improved mechanical, physical and biological properties of chitosan films using Aloe vera and electrospun PVA nanofibers for wound dressing applications

Natural polymers such as chitosan and Aloe vera are widely used in novel wound dressings due to their biocompatibility and biodegradability. A problem associated with these polymers is their poor mechanical behavior. Efforts have been made to improve the mechanical properties by mixing synthetic polymers such as PVA, but the role of chitosan and Aloe vera in the final dressing is dimmed. The techniques are also time-consuming and costly and there is still a need for an acceptable and affordable wound dressing which can be made through easily accessible techniques. A new but very simple method is introduced in this work for incorporating PVA nanofibers with Aloe vera-containing chitosan films. Using this method the levels of Aloe vera and chitosan in the system can be optimized at higher scales while benefiting from PVA best mechanical properties as a composite layer. Higher amounts of Aloe vera and chitosan in the system lead to lower product costs and more biocompability. The biological properties of films were examined through cell cytotoxicity and antibacterial tests and compared with Atomic force microscopy results. Physical and mechanical properties of films containing PVA nanofibers were characterized by water vapor permeability, swelling ratio, and tensile tests. The morphology of fibers before and after applying on the films was also observed by scanning electron microscopy. According to the results, this combination of natural and synthetic polymers has led to an affordable, biocompatible, and flexible film for wound dressing applications.

Stearic acid grafted chitosan/epoxy blend surface coating for prolonged protection of mild steel in saline environment

Chitosan (CS) is a promising candidate for green anticorrosive coating owing to its film forming nature, complexation with metals, biocompatibility, and varied surface functionalization. This paper illustrates the surface properties of chitosan film which is modified by grafting with stearic acid via a water-soluble coupling agent, 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC). The interaction between chitosan and stearic acid were investigated theoretically by Gaussian 09 package. The purified co polymeric films so formed were characterized by FTIR-ATR, NMR, XRD, TGA, CHNSO, SEM, AFM and EDX techniques. Stearic acid grafted CS film was developed on mild steel surface via dip coating technique and investigated for its corrosion resistance in 3.5% NaCl via electrochemical techniques. EIS measurements and potentiodynamic polarization studies have proven that the grafted CS when blended with epoxy resin offers better corrosion protection to mild steel in saline environment. The coating offers prolonged protection for the metal surface with enhanced barrier properties and hydrophobic nature.

Vanillin as a natural cross-linking agent in chitosan-based films: Optimizing formulation by response surface methodology

Abstract One way of improving mechanical and water barrier properties of chitosan films is through cross-linking reactions. Cross-linking agents usually used for this purpose include glutaraldehyde, glyoxal, and formaldehyde, which may cause some undesirable side effects and are consider health hazards. Hence, the objective of this work was to optimize the formulation of chitosan (CH) films with vanillin as a natural antioxidant cross-linking agent, to simultaneously improve their physical, barrier, antioxidant and mechanical properties. Three parameters were studied at three levels: vanillin content (0, 25 and 50% w/w chitosan), glycerol content (30, 45 and 60% w/w chitosan) and drying temperature (35, 50 and 65 °C). Response surface methodology (RSM) and desirability function (D) were used to find the levels of each factor that simultaneously optimize different properties of the films: opacity value, total soluble matter (TSM), Young modulus (YM), T0 and Tmax parameters (obtained from thermogravimetric analysis), water vapor permeability (WVP), total phenolic content (TPC) and antioxidant capacity by DPPH method. Fifteen formulations combining the studied factors were prepared according to a Box-Behnken design. An optimal chitosan film formulation was found, with vanillin content of 37.5% (w/w of CH), glycerol content of 45% (w/w of CH) and drying temperature of 57.5 °C. RSM approach using the desirability function was found to be an effective tool to investigate changes in films properties and to search for the optimal active chitosan film formulation with a natural cross-linking agent, such as vanillin.

Structural characterization and properties of polyols plasticized chitosan films

In this study, the influence of different polyols such as glycerol, xylitol and maltitol on the crystalline structure and thermal properties of chitosan films were investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The concentration of polyol was fixed at 20 wt%. FTIR result showed that the addition of polyols weakened the hydrogen bonding between chitosan molecules, whereas the electrostatic interactions remained nearly unchanged. Structural analysis revealed that the plasticizer which promoted the crystallization of chitosan was moisture rather than polyol contained in the polymer films. DSC result indicated that glycerol plasticized film had a lower glass transition temperature (Tg) and lower melting temperature (Tm). The low thermal transition temperatures suggested that the moisture content is higher in glycerol plasticized film, which was evidenced by TGA result. In addition, the polyols incorporation resulted in a decrease of the tensile strength of chitosan films, while their ductility was improved. These observations indicate that the addition of polyols as plasticizers could regulate the microstructure as well as the properties of chitosan films, which is essential for their usage in food industry.

Preparation and characterization of antioxidant, antimicrobial and pH-sensitive films based on chitosan, silver nanoparticles and purple corn extract

In this study, silver nanoparticles (AgNPs) and anthocyanin-rich purple corn extract (PCE) were incorporated into chitosan to develop active and intelligent food packaging films. The structural, physical and functional properties of chitosan/AgNPs/PCE films were compared with those of chitosan, chitosan/AgNPs and chitosan/PCE films. Spectroscopic analysis showed seven kinds of anthocyanins were present in PCE. Some particles and spots appeared on the surfaces and cross-sections of composite films. Fourier transform infrared and X-ray diffraction analyses suggested the interactions between chitosan and AgNPs were based on coordination effect, whereas the interactions between chitosan and PCE were mainly established through hydrogen bonds. The incorporation of PCE and/or AgNPs remarkably promoted the light and water vapor barrier ability, mechanical strength, antioxidant and antimicrobial properties of chitosan film. Notably, chitosan/AgNPs/PCE film exhibited the highest barrier, mechanical, antioxidant and antimicrobial properties due to synergistic effect between PCE and AgNPs. Besides, chitosan/PCE and chitosan/AgNPs/PCE films could change their colors in different pH buffers because of abundant anthocyanins in PCE. Our results suggested chitosan/AgNPs/PCE film could be used as novel active and intelligent food packaging material in food industry.

Effects of anthocyanin-rich purple and black eggplant extracts on the physical, antioxidant and pH-sensitive properties of chitosan film

Active and intelligent food packaging films were developed by mixing chitosan (CS) with anthocyanin-rich purple eggplant extract (PEE) or black eggplant extract (BEE). Results showed the anthocyanin contents in PEE and BEE were 93.10 and 173.17 mg/g, respectively. Besides, the anthocyanin compositions of PEE and BEE were totally different. PEE and BEE increased the blueness, thickness, UV–vis light barrier and mechanical properties of CS film. Nevertheless, PEE did not change the moisture content of CS film and BEE did not change the water vapor permeability of CS film. Microstructure observation showed low contents (1 and 2 wt%) of PEE and BEE were well distributed in CS matrix. Fourier transform infrared spectroscopy revealed the existence of intermolecular interactions between CS and extracts. X-ray diffraction indicated PEE and BEE somewhat increased the crystallinity of CS film. The antioxidant ability of CS film was remarkably enhanced by PEE and BEE. Moreover, CS-PEE and CS-BEE films were pH-sensitive and showed remarkable color changes in different buffer solutions, which could be used to monitor milk spoilage. Our results suggested CS-PEE and CS-BEE films could be applied as active and intelligent food packaging materials.

Effect of molecular weight on the properties of chitosan films prepared using electrostatic spraying technique

Chitosan (CH) films were prepared with different number-average molecular weight (MW, ca. 6.55, 12.93 and 47.70 kDa) and concentration (0.5, 0.75, and 1.0%) using electrostatic spraying (ES) technique. The effects of MW on film-forming solution properties, ES-atomization performances, and film characteristics were investigated. With increase of MW, conductivity, viscosity, surface tension, and contact angle of CH film-forming solution was raised due to the increases of proportions of amine-groups and degrees of CH chain entanglements. Spray cone angle was generally higher at 12.93 kDa, while the average median diameters of film-forming solution droplets were in the range of 6.3–12.0 μm, indicating well atomization effect. Water barrier property and tensile strength of CH films were improved along with increased MW, which was in accordance with the more completed, rougher and more crystalline microstructures implying by SEM, AFM and XRD. However, film antibacterial capacities against E.coli and L. innocua were descended with increased MW. Considering the overall properties, CH film prepared by 47.70 kDa at 0.5% possessed the best performances.

Tailoring physicochemical properties of chitosan films and their protective effects on meat by varying drying temperature

A higher temperature is usually used to increase the evaporation rate and thus reduce the drying time of chitosan films during casting preparation process. The effects of drying temperature (45–85 °C) on the microstructure, mechanical and barrier properties of chitosan films were investigated. Chitosan films dried at higher temperatures showed smoother internal microstructures by forming smaller micro-region aggregations and lower ordered crystalline structures. Higher drying temperature also decreased the intermolecular interactions of chitosan chains according to Fourier transform infrared spectroscopy analysis. These together led to the decrease in tensile strength, and the increase in water vapor and oxygen permeability. The film surface hydrophobicity remained unchanged at different drying temperatures, suggesting the applicability for chilled meat preservation. Chilled meat packaged with chitosan films had appropriate drip loss rate values as compared to those of the low-density polyethylene film and the blank sample, with lower thiobarbituric acid reactive substances, aerobic plate count, pH, and total volatile basic nitrogen values during 10 d storage. Moreover, films dried at lower temperatures showed superior juice retention capacity as well as superior preservation effect on chilled meat. The results found in this study can be used to better guide the selecting of drying temperature for chitosan film preparation.

Influence of natural plasticizers derived from forestry biomass on shrimp husk chitosan films

Three new natural plasticizers (exudates of the Prosopis pallida and Capparis scabrida trees and gum from the Cordia lutea fruit) and polyvinyl alcohol (PVA) in different concentrations were tested to determine their influence on the properties of chitosan films prepared by a casting method. Properties such as thickness, solubility, water vapor permeability, elongation at break, tensile strength, luminosity, and anaerobic biodegradability were evaluated. Chitosan films with exudate of the Capparis scabrida tree as plasticizer had better properties than those with the other two natural plasticizers. However, the mechanical properties of the chitosan films prepared with PVA were still better than those with exudate of the Capparis scabrida tree. The films that included the three natural plasticizers in their composition were more biodegradable than those made of PVA, with films with exudate of the Capparis scabrida tree being the most biodegradable. The exudate of the Capparis scabrida tree is a potential biodegradable plasticizer for use in medical or food applications.

Improvement of the physical properties of chitosan by γ-ray degradation for wound healing

Abstract Improving the physical properties of chitosan films by irradiation with different doses (5, 10, 15, 20 and 25 kGy) of γ-rays to be used as a wound healing material. Mechanical properties and dielectric spectroscopy were measured for the films. Results showed that at low γ-dose, tensile strength (TS) elongation percent (E%) increase, while E-modulus, e′, e″ and δA.C decrease due to the accumulation of ions between the chitosan chains which make a bulk network due to hydrogen bonds. This will make the film more elastic and high biodegradable which is preferred in wound healing. While the contrary was observed by increasing the radiation dose, chain scission occur resulting in weak chitosan interchain bonds and this will increase the mobility of the segments which increase the rigidity. In conclusion, the dose of 5 kGy was the most optimum for the properties of chitosan films used in the application of wound healing.

Preparation and characterization of antioxidant and pH-sensitive films based on chitosan and black soybean seed coat extract

Antioxidant and pH-sensitive chitosan based films were developed by incorporating different amounts of black soybean seed coat extract (BSSCE). Spectroscopic analysis showed the main anthocyanins in BSSCE were cyanidin-3-O-galactoside (21.38%), cyanidin-3-O-glucoside (63.30%) and peonidin-3-O-glucoside (11.92%). Incorporation of BSSCE could greatly alter the barrier, optical and mechanical properties of chitosan film. Notably, chitosan-BSSCE films presented better water vapor and UV–vis light barrier properties and higher mechanical strength than chitosan film. However, chitosan-BSSCE films exhibited lower moisture content and transparency than chitosan film. Among all films tested, chitosan-BSSCE film containing 15 wt% of BSSCE on chitosan basis exhibited the best performance. Scanning electron microscopy showed BSSCE was uniformly distributed in chitosan-BSSCE films. Fourier transform infrared spectra of chitosan-BSSCE films further revealed chitosan could interact with BSSCE through non-covalent bonds. Importantly, chitosan-BSSCE films showed dose- and time-dependent 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity. Moreover, color variations were observed in chitosan-BSSCE films by changing pH. Results suggested chitosan-BSSCE films could be used as promising antioxidant and visible pH-sensing food packing materials.

Effect of deacetylation degree on properties of Chitosan films using electrostatic spraying technique

Chitosan (CH) films at 4.4 kDa with different deacetylation degree (DD, 81.0, 88.1 and 95.2%) and concentration (0.9, 1.2 and 1.5%) were prepared using electrostatic spraying (ES) system. The effects of DD and concentration on film-forming solution properties, ES-atomization effects, and film performances were investigated. Results indicated that surface tension and viscosity of CH solution declined with the increase of DD, while solution conductivity displayed the opposite trend. The spray angles of film-forming solution during ES were in the range of 10.6–14.2°, and the average median diameters of droplet sizes were all ranged from 6.4 to 13.9 μm. The spray angle and droplet size generally reduced with increasing DD, and thus more complete, rougher and more crystalline microstructures of CH films were observed by SEM, AFM and XRD. CH films at 88.1 and 95.2% DD had better water barrier property and tensile strength. In addition, antibacterial capacities of CH films against L.innocua and E. coli were enhanced with DD. The results could provide guidance on the application of ES technology to improve the commercial food safety such as, fruits, vegetables, poultry, meat, and seafood.