Modified Chitosan Films Research Articles

Effect of cinnamaldehyde–tannic acid-zinc acetate nanoparticles and aldehyde crosslinking on properties of chitosan films and their application for beef preservation

Pure chitosan films are relatively fragile and tend to dissolve when they come into contact with water, which limits their application in food preservation. In this study, cinnamaldehyde-tannic acid-zinc acetate (CTZA) nanoparticles and aldehyde crosslinking were used to enhance the mechanical and water barrier properties of chitosan films. Fourier transform infrared spectroscopy and X-ray diffraction analyses showed that cinnamaldehyde had been successfully grafted on the surfaces of chitosan films. The thermal stability and mechanical property of the chitosan films were greatly improved after these modifications. Compared to non-modified films, the tensile strength of modified films increased by about 1.5- and 8.2-fold under dry and wet conditions, respectively. In addition, the moisture content, swelling degree, water solubility, and water vapor permeability of the modified films were all significantly decreased after the aldehyde modification. Interestingly, the modified film showed no significant changes in dimensions after being immersed in water for 24 h. Moreover, the UV-blocking properties and antioxidant activity of the modified films were significantly enhanced. Finally, the modified films extended the shelf life of packaged beef by 5 d. These findings suggest that the modified chitosan films can be used as active packaging materials for food preservation.

A grafting approach for nisin-chitosan bio-based antibacterial films: preparation and characterization

Nisin is a bacteriocin produced by Gram-positive lactic acid bacterium,Lactococcus lactisand currently recognized in the Generally Recognızed as Safe (GRAS) category due to its non-toxicity. Herein, nisin has been grafted to chitosan structure to obtain natural bio-active films with enhanced antibacterial activity. Grafting was performed using ethyl ester lysine diisocyanate and dimer fatty acid-based diisocyanate (DDI); two different close to fully bio-based diisocyanates and Disuccinimidyl suberate; a homo-bifunctional molecule acting as a crosslinker between amino groups. The grafting process allowed the chemical immobilization of nisin to chitosan structure. Physicochemical characterization studies showed the successful grafting of nisin. The antibacterial activity againstStaphylococcus aureuswas evident for all nisin modified chitosan films and best pronounced when DDI was used as a crosslinker with a maximum zone of inhibition of ∼13 mm. All nisin grafted chitosan films were cytocompatible and the cell viability of L929 fibroblasts were >80% pointing out the non-toxic structure. Considering the results of the presented study, bio-based diisocyanates and homo-bifunctional crosslinkers are effective molecules in synthesis of nisin grafted chitosan structures and the new chitosan based antibacterial biopolymers obtained after nisin modification come forward as promising non-toxic and bioactive candidates to be applied in medical devices, implants, and various food coating products.

Biodegradability Study of Modified Chitosan Films with Cinnamic Acid and Ellagic Acid in Soil.

Currently, natural polymer materials with bactericidal properties are extremely popular. Unfortunately, although the biopolymer material itself is biodegradable, its enrichment with bactericidal compounds may affect the efficiency of biodegradation by natural soil microflora. Therefore, the primary objective of this study was to evaluate the utility of fungi belonging to the genus Trichoderma in facilitating the degradation of chitosan film modified with cinnamic acid and ellagic acid in the soil environment. Only two strains (T.07 and T.14) used chitosan films as a source of carbon and nitrogen. However, their respiratory activity decreased with the addition of tested phenolic acids, especially cinnamic acid. Addition of Trichoderma isolates to the soil increased oxygen consumption during the biodegradation process compared with native microorganisms, especially after application of the T.07 and T.14 consortium. Isolates T.07 and T.14 showed high lipolytic (55.78 U/h and 62.21 U/h) and chitinase (43.03 U/h and 41.27 U/h) activities. Chitinase activity after incorporation of the materials into the soil was higher for samples enriched with T.07, T.14 and the consortium. The isolates were classified as Trichoderma sp. and Trichoderma koningii. Considering the outcomes derived from our findings, it is our contention that the application of Trichoderma isolates holds promise for expediting the degradation process of chitosan materials containing bactericidal compounds.

Application Potential of Trichoderma in the Degradation of Phenolic Acid-Modified Chitosan.

The aim of the study was to determine the potential use of fungi of the genus Trichoderma for the degradation of phenolic acid-modified chitosan in compost. At the same time, the enzymatic activity in the compost was checked after the application of a preparation containing a suspension of the fungi Trichoderma (spores concentration 105/mL). The Trichoderma strains were characterized by high lipase and aminopeptidase activity, chitinase, and β-1,3-glucanases. T. atroviride TN1 and T. citrinoviride TN3 metabolized the modified chitosan films best. Biodegradation of modified chitosan films by native microorganisms in the compost was significantly less effective than after the application of a formulation composed of Trichoderma TN1 and TN3. Bioaugmentation with a Trichoderma preparation had a significant effect on the activity of all enzymes in the compost. The highest oxygen consumption in the presence of chitosan with tannic acid film was found after the application of the consortium of these strains (861 mg O2/kg after 21 days of incubation). Similarly, chitosan with gallic acid and chitosan with ferulic acid were found after the application of the consortium of these strains (849 mgO2/kg and 725 mg O2/kg after 21 days of incubation). The use of the Trichoderma consortium significantly increased the chitinase activity. The application of Trichoderma also offers many possibilities in sustainable agriculture. Trichoderma can not only degrade chitosan films, but also protect plants against fungal pathogens by synthesizing chitinases and β-1,3 glucanases with antifungal properties.

A soft multifunctional film from chitosan modified with disulfide bond cross-links and prepared by a simple method

Chitosan was modified with thioctic acid and used to prepare soft films. As confirmed by FTIR and XPS measurements, a condensation reaction occurred between the amino groups in the chitosan and the carboxyl groups in the lipoic acid to form amide bonds in the modified chitosan. Films were then prepared by casting at ambient conditions, and the effects of the chemical modification on the physical-mechanical, antibacterial, and thermal properties of the films were investigated. The results showed that the tensile strength, flexibility and recovery performance of the modified films were significantly different from those of the unmodified films. For example, the Young's modulus of a pure chitosan film was 2600 MPa, while the modified films were much more flexible with a Young's modulus as low as 32.5 MPa. Moreover, the modified chitosan films were not dissolved or damaged by common organic solvents or in highly acidic (pH 1) or highly basic (pH 13) conditions. The modified films also showed good antibacterial activity against both E coli and S aureus with inhibition rates of almost 100 %. These desirable properties suggest that the modified chitosan films prepared here have possible application prospects in flexible devices and packaging.

Enhancing antifungal properties of chitosan by attaching isatin-piperazine-sulfonyl-acetamide pendant groups via novel imidamide linkage

World health organization listed fungi as priority pathogens in 2022 to counter their adverse effects on human well-being. The use of antimicrobial biopolymers is a sustainable alternative to toxic antifungal agents. In this study, we explore chitosan as an antifungal agent by grafting a novel compound N-(4-((4-((isatinyl)methyl)piperazin-1-yl)sulfonyl)phenyl) acetamide (IS). The acetimidamide linkage of IS to chitosan herein was confirmed by 13C NMR and is a new branch in chitosan pendant group chemistry. The modified chitosan films (ISCH) were studied using thermal, tensile, and spectroscopic methods. The ISCH derivatives strongly inhibit fungal pathogens of agricultural and human importance, namely Fusarium solani, Colletotrichum gloeosporioides, Myrothecium verrucaria, Penicillium oxalicum, and Candida albicans. ISCH80 showed an IC50 value of 0.85 μg/ml against M. verrucaria and ISCH100 with IC50 of 1.55 μg/ml is comparable to the commercial antifungal IC50 values of Triadiamenol (3.6 μg/ml) and Trifloxystrobin (3 μg/ml). Interestingly, the ISCH series remained non-toxic up to 2000 μg/ml against L929 mouse fibroblast cells. The ISCH series showed long-standing antifungal action, superior to our lowest observed antifungal IC50 values of plain chitosan and IS at 12.09 μg/ml and 3.14 μg/ml, respectively. ISCH films are thus suitable for fungal inhibition in an agricultural setting or food preservation.

Chitosan Grafted with Thermoresponsive Poly(di(ethylene glycol) Methyl Ether Methacrylate) for Cell Culture Applications

Chitosan is a polysaccharide extracted from animal sources such as crab and shrimp shells. In this work, chitosan films were modified by grafting them with a thermoresponsive polymer, poly(di(ethylene glycol) methyl ether methacrylate) (PMEO2MA). The films were modified to introduce functional groups useful as reversible addition-fragmentation chain transfer (RAFT) agents. PMEO2MA chains were then grown from the films via RAFT polymerization, making the chitosan films thermoresponsive. The degree of substitution of the chitosan-based RAFT agent and the amount of monomer added in the grafting reaction were varied to control the length of the grafted PMEO2MA chain segments. The chains were cleaved from the film substrates for characterization using 1H NMR and a gel permeation chromatography analysis. Temperature-dependent contact angle measurements were used to demonstrate that the hydrophilic-hydrophobic nature of the film surface varied with temperature. Due to the enhanced hydrophobic character of PMEO2MA above its lower critical solution temperature (LCST), the ability of PMEO2MA-grafted chitosan films to serve as a substrate for cell growth at 37 °C (incubation temperature) was tested. Interactions with cells (fibroblasts, macrophages, and corneal epithelial cells) were assessed. The modified chitosan films supported cell viability and proliferation. As the temperature is lowered to 4 °C (refrigeration temperature, below the LCST), the grafted chitosan films become less hydrophobic, and cell adhesion should decrease, facilitating their removal from the surface. Our results indicated that the cells were detached from the films following a short incubation period at 4 °C, were viable, and retained their ability to proliferate.

Surface modification of film chitosan materials with aldehydes for wettability and biodegradation control

Chitosan is one of the prospective polymers for use in regenerative medicine which has unique properties such as biocompatibility, biodegradability, antimicrobial, anti-inflammatory, and antitumor potency. In this article, we study the peculiarities of the surface modification of chitosan films with carbonyl-containing compounds, which differed both in molecular characteristics and in their hydrophilic and hydrophobic properties. The potential for controlling the biodegradation of the resulting materials has been established, which can be used in the creation of wound dressings. Both the destruction time and lyophilic properties of the surface depend on the length of the modifier’s hydrocarbon radical. The contact angle and water absorption of obtained film materials correlate with hydrophobicity, which estimated by the calculated value of the hydrophilic–lipophilic balance. The cytotoxicity of modified chitosan films was studied, and it was found that they are non-toxic (cytotoxic index of < 50%) for human skin cell cultures, which shows their potential for use in the creation of materials for skin protection and external wound healing.

Glycerol‐plasticized chitosan film for the preservation of orange

AbstractGreen thin films for food packaging are essential and growing in recent years to reduce the dependence on petroleum‐derived plastics. In this study, the glycerol‐plasticized chitosan film incorporated with 1–3% of crude Piper betel Linn. leaf (PBLL) extract was prepared via facile casting process and was characterized by scanning electron microscope, attenuated total reflection‐Fourier transform infrared, thermogravimetric analysis, X‐ray diffraction, UV–Vis, contact angle, water content, antimicrobial, and antioxidant activities. The film improved the protective properties of the sole chitosan and enhanced the UV‐blocking ability of glycerol‐plasticized chitosan film in the regions of Ultraviolet B (280–320 nm) and Ultraviolet A (320–390 nm), resulting in suitable film for food packaging applications. Furthermore, the presence of PBLL extract predominantly containing phenolic compounds in blend film induced very strong antimicrobial activities against Staphylococcus aureus, Pseudomonas aeruginosa, Salmonella typhimurium, and Escherichia coli. The modified chitosan films increased the hydrophilic property resulting in high potential in degradability and can also protect the king orange by coating with the shelf life‐prolonging up to 18 days at 20°C with acceptable appearance and texture. Our results can be developed to produce industrial green thin films to protect fruits during transportation and preservation.

Chitosan as a Protective Matrix for the Squaraine Dye.

Chitosan was used as a protective matrix for the photosensitive dye-squaraine (2,4-bis[4-(dimethylamino)phenyl]cyclobutane-1,3-diol). The physicochemical properties of the obtained systems, both in solution and in a solid-state, were investigated. However, it was found that diluted chitosan solutions with a few percent additions of dye show an intense fluorescence, which is suppressed in the solid-state. This is related to the morphology of the heterogeneous modified chitosan films. The important advantage of using a biopolymer matrix is the prevention of dye degradation under the influence of high energy ultraviolet (UV) radiation while the dye presence improves the chitosan heat resistance. It is caused by mutual interactions between macromolecules and dye. Owing to the protective action of chitosan, the dye release in liquid medium is limited. Chitosan solutions with a few percent additions of squaraine can be used in biomedical imaging thanks to the ability to emit light, while chitosan films can be protective coatings resistant to high temperatures and UV radiation.

Solid-phase luminescence of pyrene in chitosan adsorbents

The preparation method of modified chitosan films for adsorption of pyrene from solution is described. Solid-phase luminescence of samples was studied, degree of extraction and index of polarity of microenvironment of pyrene molecules was determined. It has been proven possible to carry out luminescent analysis of substances for pyrene content using made films. The observed results demonstrate an ability for the using method of solid-phase luminescence (SPL) to increase the range of optical transparency and avoid pre-extraction and concentration of the test samples .

Assessment of active chitosan films incorporated with gallic acid

Chitosan films with antioxidant and antimicrobial properties were prepared by the incorporation of gallic acid as a bioactive. The films obtained were homogeneous, transparent and colorless with high mechanical resistance. Results indicated that films had antimicrobial activity against E. coli, especially those films plasticized with 15 wt % glycerol and containing 20 wt % gallic acid, which showed the biggest inhibition halo. Additionally, gallic acid-incorporated chitosan films exhibited a great antioxidant activity with DPPH scavenging capacity values of 99% and a bioactive release of 33% after 4 days, suggesting the potential suitability of these modified chitosan films as active films for food or pharmaceutical purposes.

Understanding the effect of formulation on functionality of modified chitosan films containing carvacrol nanoemulsions

The interest towards the use of films and coatings in food preservation has been reinforced in the recent years by the development of biopolymeric matrices incorporating essential oil as antimicrobial barriers in food as an alternative to synthetic additives.This work has therefore been addressed to investigate the effect of composition parameters on antimicrobial activity and properties of films based on modified chitosan containing different types of carvacrol nanoemulsions. Specifically, response surface methodology, applied for the concentration of biopolymer and carvacrol nanoemulsion in the film forming dispersions to maximize the antimicrobial activity against two model microorganisms, Escherichia coli and Listeria innocua, as well as surface hydrophobicity, was used to determine the optimum conditions for comparison of most promising systems.Results showed that emulsion formulations had a significant effect on the intrinsic antimicrobial activity, but also that their interaction with the modified chitosan matrix affected film properties and resulting bactericidal action. The two most active emulsion formulations, based on a combination of polysorbate 20 and glycerol monooleate, and on whey protein isolates, respectively, when incorporated in modified chitosan films significantly increased the inhibition zone against E. coli and L. innocua from 7.2–7.4 mm (modified chitosan alone) to 13.4–16.1 mm, while still ensuring surface hydrophobicity of the film. In comparison to the use of pure carvacrol, the encapsulation into nanoemulsions also fostered the production of more homogeneous films with better appearance.This work hence contributes to promoting, through the advancement of the knowledge in the field, the incorporation of nanoemulsions of essential oils in edible films and coatings for integrated food preservation strategies.

Development and characterization of chitosan-based antimicrobial films incorporated with streptomycin loaded starch nanoparticles

Nowadays, Chitosan has attained more attention due to its potential applications in food, agriculture and pharmaceutics. The cationic nature of chitosan enhances the film forming capacity of this polymer. However, films made only from chitosan lack water resistance and have reduced mechanical properties. The functional properties of chitosan films can be improved when chitosan films are combined with other film forming materials. The objective of this study was to prepare chitosan based antimicrobial films by the incorporation of streptomycin loaded starch Nanocrystals. Different properties of this film such as swelling nature, moisture content, degradation nature and the antimicrobial activity of modified chitosan films were investigated. Drug releasing efficacy of the film was also studied. The addition of streptomycin loaded Starch nanocrystals in chitosan-gelatin film increased crystallinity of the film, lowered the swelling nature of the film to a controlled manner. Moreover the Modified chitosan based antimicrobial film showed almost 90% of Escherichia coli inhibition and 80% of Bacillus subtilis inhibition and also the film showed a sustained release (60%) of streptomycin for 10 days. Focal point•BenchsideSynthesis of streptomycin loaded starch nanoparticles (SS-NPs) using nanoprecipitation method and the development of novel chitosan based antimicrobial film by the incorporation of streptomycin loaded starch nanoparticles using solvent casting technique•BedsideDevelopment of potential multifunctional antimicrobial film for medical, pharmaceutical and food based applications due to its excellent film forming ability, biocompatibility, biodegradability and antimicrobial property•IndustryThe designed unique antimicrobial film, if finely tuned, can be used both in biomedical fields for developing scaffolds in tissue engineering, wound dressing material, capsule material for sustained drug release and immobilization of enzyme and food industry as packaging material•GovernmentFinancial investment and support from government would help to develop new novel translational tools which contribute for better health care and also help to reduces disease burden•RegulatoryStringent regulatory principles limit the clinical trials essential for validation of biomaterials which might have turned in to a highly beneficial multifunctional product such as antimicrobial film potentially useful both in biomedical and food industry.

Nanomechanical characterization and molecular mechanism study of nanoparticle reinforced and cross-linked chitosan biopolymer

Chitosan (CS) is a biomaterial that offers many sophisticated and innovative applications in the biomedical field owing to its excellent characteristics of biodegradability, biocompatibility and non-toxicity. However, very low mechanical properties of chitosan polymer impose restriction on its further development. Cross-linking and nanoparticle reinforcement are the two possible methods to improve the mechanical properties of chitosan films. In this research, these two methods are adopted individually by using tripolyphosphate as cross-linker and nano-hydroxyapatite as particle reinforcement. The nanomechanical characterizations under static loading conditions are performed on these modified chitosan films. It is observed that nanoparticle reinforcement provided necessary mechanical properties such as ductility and modulus. The mechanisms involved in improvement of mechanical properties due to particle reinforcement are studied by molecular dynamics (MD). Further, improvement in mechanical properties due to combination of particle reinforcement and cross-linking agent with chitosan is investigated. The stress relaxation behavior for all these types of films is characterized under dynamic loading conditions using dynamic mechanical analysis (nanoDMA) experiment. A viscoelastic solid like response is observed for all types of film with modulus relaxing by 3–6% of its initial value. A suitable generalized Maxwell model is fitted with the obtained viscoelastic response of these films. The response to nano-scratch behavior is also studied for particle reinforced composite films.

Characterization and bacterial adhesion of chitosan-perfluorinated acid films

We reported herein the study and characterization of films obtained by casting of chitosan solutions in perfluorinated acids, trifluoroacetic (TFA), perfluoropropionic (PFPA), and perfluorooctanoic (PFOA). The films were characterized by FTIR, solid state 13C NMR, X-ray, AFM, contact angle, thermogravimetric effluent analysis by mass spectrometry, and rheology. The results showed a marked influence of chain length of the perfluorinated acids on the hydrophobic/hydrophilic ratio of the modified chitosan films which was evidenced by the different characteristics observed.The material that showed greater surface stability was chitosan-PFOA. Chitosan film with the addition of PFOA modifier became more hydrophobic, thus water vapor permeability diminished compared to chitosan films alone, this new material also depicted bacterial adhesion which, together with the features already described, proves its potential in applications for bioreactor coating.

Study on the Properties of the Gelatin Modified Chitosan Films

Abstract: With the purpose to improve the mechanical properties and cut costs of chitosan films, a series of gelatin-chitosan films were prepared. The effect of gelatin content on the mechanical properites of films was studied. FT-IR spectrum and X-ray diffraction analysis showed good compatibility between gelatin and chitosan. The composite films exhibited a higher TS(tensile strengths) and ES(elongation at break) compared with chitosan film, especially when the content of gelatin in blends was 30%. The TS and ES revealed that the interaction between chitosan and gelatin was the strongest when the content of gelatin in blends was 30%. The results obtained from percent water absorption indicated these two biopolymers were high hydrophilicity polymer. The water solubility of composite films was higher than chitosan films. The results suggest that the interactions between gelatin and chitosan was good for the mechanical properties of composite films.

Preparation of N-vanillyl chitosan and 4-hydroxybenzyl chitosan and their physico-mechanical, optical, barrier, and antimicrobial properties

Chitosan derivatives such as N-vanillyl chitosan and 4-hydroxybenzyl chitosan were prepared by reacting chitosan with 4-hydroxy-3-methoxybenzaldehyde (vanillin) and 4-hydroxybenzaldehyde. Amino groups on chitosan reacts with these aldehydes to form a Schiff base intermediate, which is later on converted into N-alkyl chitosans by reduction with sodium cyanoborohydride. The chemical reaction was monitored by 1H NMR spectroscopy and the absence of aldehydic proton at 9.83ppm in NMR spectra was observed for both the modified chitosan derivatives confirming the reaction. Modified chitosan films were later prepared by solution casting method and their physico-mechanical, barrier, optical and thermal properties were studied. The results clearly indicated significant change in tensile strength, water vapour transmission rate, and haze properties of modified chitosans. Modified chitosan films were also studied for their antimicrobial activity against Aspergillus flavus. The results showed a marked reduction of aflatoxins produced by the fungus in the presence of the N-vanillyl chitosan and 4-hydroxybenzyl chitosan film discs to 98.9% and non-detectable levels, respectively.

Grafting ofchitosan with fatty acyl derivatives

The internal plasticization of chitosan with covalently linked long aliphatic branches, typically 12C, was accomplished through the condensation of the amino groups of chitosan with acidic derivatives of lauric acid, as lauroyl anhydride or lauroyl chloride, that are more reactive than the fatty acid itself. The chemical pathway led to selective N-acylation. The degree of substitution was quantitatively determined by FTIR and 1H NMR and varied between 3 and 35%. The FTIR quantitative analysis was based in a calibration mmethod with good accuracy. The modified chitosan products were soluble in neutral water and/or DMF according to the degree of substitution. The modified chitosan films were more flexible than the pristine, non-modified ones.

Physico-Mechanical and Degradation Properties of Urea-Modified Chitosan Film Photocured with 1-Vinyl-2 Pyrrolidone

Chitosan and urea modified chitosan films were prepared by solution casting. To improve the physico-mechanical properties of the chitosan/urea films, four formulations were prepared using 1-vinyl-2-pyrrolidon (NVP) (varied from 10–80% by weight) in methanol along with photo-initiator. The films were soaked (1–4 minutes) in the prepared formulations and photo-cured under UV-light at different intensities (5–35 pass). The physico-mechanical properties, polymer loading, gel content, water uptake and simulating weathering test of the NVP grafted photocured chitosan/urea film were carried out. Degradation of the chitosan/urea film was also observed. The scanning electron micrographs of the photo-cured chitosan/urea film showed smooth surface, compact and homogeneous structure.