Chitosan films and blends for packaging material

Bio- and Fossil-Based Polymeric Blends and Nanocomposites for Packaging: Structure⁻Property Relationship

In the present review, the possibilities for blending of commodities and bio-based and/or biodegradable polymers for packaging purposes has been considered, limiting the analysis to this class of materials without considering blends where both components have a bio-based composition or origin. The production of blends with synthetic polymeric materials is among the strategies to modulate the main characteristics of biodegradable polymeric materials, altering disintegrability rates and decreasing the final cost of different products. Special emphasis has been given to blends functional behavior in the frame of packaging application (compostability, gas/water/light barrier properties, migration, antioxidant performance). In addition, to better analyze the presence of nanosized ingredients on the overall behavior of a nanocomposite system composed of synthetic polymers, combined with biodegradable and/or bio-based plastics, the nature and effect of the inclusion of bio-based nanofillers has been investigated.

Biocompatible Chitosan Nanobubbles for Ultrasound-Mediated Targeted Delivery of Doxorubicin

Ultrasound-targeted delivery of nanobubbles (NBs) has become a promising strategy for noninvasive drug delivery. The biosafety and drug-transporting ability of NBs have been a research hotspot, especially regarding chitosan NBs due to their biocompatibility and high biosafety. Since the drug-carrying capacity of chitosan NBs and the performance of ultrasound-assisted drug delivery remain unclear, the aim of this study was to synthesize doxorubicin hydrochloride (DOX)-loaded biocompatible chitosan NBs and assess their drug delivery capacity. In this study, the size distribution of chitosan NBs was measured by dynamic light scattering, while their drug-loading capacity and ultrasound-mediated DOX release were determined by a UV spectrophotometer. In addition, a clinical ultrasound imaging system was used to evaluate the ability of chitosan NBs to achieve imaging enhancement, while the biosafety profile of free chitosan NBs was evaluated by a cytotoxicity assay in MCF-7 cells. Furthermore, NB-mediated DOX uptake and the apoptosis of Michigan Cancer Foundation-7 (MCF-7) cells were measured by flow cytometry. The results showed that the DOX-loaded NBs (DOX-NBs) exhibited excellent drug-loading ability as well as the ability to achieve ultrasound enhancement. Ultrasound (US) irradiation promoted the release of DOX from DOX-NBs in vitro. Furthermore, DOX-NBs effectively delivered DOX into mammalian cancer cells. In conclusion, biocompatible chitosan NBs are suitable for ultrasound-targeted DOX delivery and are thus a promising strategy for noninvasive and targeted drug delivery worthy of further investigation.

Synthetic poly(vinyl alcohol)–chitosan as a new type of highly efficient hemostatic sponge with blood-triggered swelling and high biocompatibility

Synthetic poly(vinyl alcohol)–chitosan as a new type of highly efficient hemostatic sponge with blood-triggered swelling and high biocompatibility.

Hydrophobization of chitosan films by surface grafting with fluorinated polymer brushes

Chitosan with its surface-properties and biodegradability is a promising biomaterial for green packaging applications. Till now, this application is still limited due to chitosan high sensitivity to water. Some existing studies deal with the incorporation of hydrophobic additives to enhance water-proof performances of chitosan films. As these additives may impair the film properties, our study focuses on chitosan efficient hydrophobization by means of simple and successful surface grafting reactions. Chitosan films prepared by solvent casting were modified by means of surface-initiated activators regenerated by electron transfer atom radical polymerization (SI-ARGET-ATRP) of 2-hydroxyethyl methacrylate (HEMA) followed by esterification reaction with fluorinated acyl compound. X-ray photoelectron spectroscopy (XPS), attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and Time-of-Flight Secondary Ion Mass Spectroscopy (ToF-SIMS) highlighted the surface chemical changes after each step. Surface properties were investigated by contact angle measurements and surface energy calculations. Hydrophobic surfaces with low surface energy and good water-repellent properties were obtained using a simple handling polymerization procedure. This is the first study in applying ARGET ATRP to prepare hydrophobic biopolymer films offering potential applications in packaging.

Current advancements in chitosan-based film production for food technology; A review

Chitosan is obtained from chitin, which could be considered to be the most abundant polymer after cellulose. Owing to these properties, chitosan alone or chitosan-based composite film production is attaining huge attention in terms of applications from researchers and industrialists coming from divergent fields. To enhance the biological (mainly antimicrobial and antioxidant) and physiological (mainly mechanical, thermal and barrier) attributes of the chitosan-based films, a vast medley of plant extracts and supporting polymers has been blended into chitosan films. Considering the up to date literature reports based on chitosan film production and applications, it can be stated that still, the research ratio is low in this field. Chitosan blend/composite films with specific properties (superhydrophobicity, excellent mechanical strength, acceptable barrier properties) can be produced only for specific applications in food technology. In the current review, we tried to summarize the advancements made in the last 5-7 years in the field of chitosan film technology for its application in the food industry.

Effect of chitosan addition on the properties of films prepared with corn and cassava starches

Starch and chitosan are biodegradable polymers from renewable sources that can be used to overcome the serious environmental problem caused by improper disposal of synthetic plastic materials, non-biodegradable, derived from petroleum sources. The starch-chitosan based films manufactured allow improving the better characteristics of each one, adding their good characteristics and compensating for some limitations. In this work, it was studied: two sources of starch (corn and cassava), two different modes of chitosan addition (chitosan blended in the starch filmogenic solution and chitosan as coating), and the effect of glutaraldehyde as crosslinking agent. All films were prepared by casting using glycerol as a plasticizer and were characterized by their physicochemical (water vapor permeability, water contact angle, and FTIR), mechanical, and antimicrobial properties. The properties analyzed were influenced by all variables tested. Moreover, the principal component analysis was also conducted in order to relate and describe the variables analyzed. The antimicrobial activity of the corn starch-based films containing chitosan was confirmed, and these films have potential for development of active packaging.

Development of antibacterial ε-polylysine/chitosan hybrid films and the effect on citrus

In this study, the ε-polylysine (PL)/chitosan (CS) composite films with the PL concentration of 0%, 1%, 3%, 5% and 7% were prepared via casting method. The Fourier transform infrared (FTIR), scanning electron microscope (SEM), mechanical and antibacterial properties of PL/CS composite films, as well as the effect of PL/CS coatings on citrus were observed. FTIR spectra suggested that there was no strong hydrogen bond between CS and PL. SEM images indicated that the film surface was smooth and the addition of PL to chitosan lead to more holes. The tensile strength was deceasing and the elongation at break of the films was elevating with the increase of PL content. The antibacterial activity against Staphylococcus aureus and Escherichia coli of PL/CS composite films was enhanced with increasing of PL content. Furthermore, it was found that the PL/CS coatings inhibited efficiently the decline of total soluble solids (TSS), ascorbic acid content and reduced the disease incidence of citrus, compared with the control. Also the disease incidence of citrus was decreasing with the increase of PL content. However, the weight loss did not show significant differences between the coated citrus and control during the whole storage period.

β-N-Acetylglucosaminidase MthNAG from Myceliophthora thermophila C1, a thermostable enzyme for production of N-acetylglucosamine from chitin

Thermostable enzymes are a promising alternative for chemical catalysts currently used for the production of N-acetylglucosamine (GlcNAc) from chitin. In this study, a novel thermostable β-N-acetylglucosaminidase MthNAG was cloned and purified from the thermophilic fungus Myceliophthora thermophila C1. MthNAG is a protein with a molecular weight of 71 kDa as determined with MALDI-TOF-MS. MthNAG has the highest activity at 50 °C and pH 4.5. The enzyme shows high thermostability above the optimum temperature: at 55 °C (144 h, 75% activity), 60 °C (48 h, 85% activity; half-life 82 h), and 70 °C (24 h, 33% activity; half-life 18 h). MthNAG releases GlcNAc from chitin oligosaccharides (GlcNAc)_2–5, p-nitrophenol derivatives of chitin oligosaccharides (GlcNAc)_1–3-pNP, and the polymeric substrates swollen chitin and soluble chitosan. The highest activity was detected towards (GlcNAc)₂. MthNAG released GlcNAc from the non-reducing end of the substrate. We found that MthNAG and Chitinase Chi1 from M. thermophila C1 synergistically degraded swollen chitin and released GlcNAc in concentration of approximately 130 times higher than when only MthNAG was used. Therefore, chitinase Chi1 and MthNAG have great potential in the industrial production of GlcNAc.

Chitinase Chi1 from Myceliophthora thermophila C1, a Thermostable Enzyme for Chitin and Chitosan Depolymerization

A thermostable Chitinase Chi1 from Myceliophthora thermophila C1 was homologously produced and characterized. Chitinase Chi1 shows high thermostability at 40 °C (>140 h 90% activity), 50 °C (>168 h 90% activity), and 55 °C (half-life 48 h). Chitinase Chi1 has broad substrate specificity and converts chitin, chitosan, modified chitosan, and chitin oligosaccharides. The activity of Chitinase Chi1 is strongly affected by the degree of deacetylation (DDA), molecular weight (Mw), and side chain modification of chitosan. Chitinase Chi1 releases mainly (GlcNAc)₂ from insoluble chitin and chito-oligosaccharides with a polymerization degree (DP) ranging from 2 to 12 from chitosan, in a processive way. Chitinase Chi1 shows higher activity toward chitin oligosaccharides (GlcNAc)_4-6 than toward (GlcNAc)₃ and is inactive for (GlcNAc)₂. During hydrolysis, oligosaccharides bind at subsites -2 to +2 in the enzyme's active site. Chitinase Chi1 can be used for chitin valorisation and for production of chitin- and chito-oligosaccharides at industrial scale.

Emerging Chitosan-Based Films for Food Packaging Applications

Recent years have witnessed great developments in biobased polymer packaging films for the serious environmental problems caused by the petroleum-based nonbiodegradable packaging materials. Chitosan is one of the most abundant biopolymers after cellulose. Chitosan-based materials have been widely applied in various fields for their biological and physical properties of biocompatibility, biodegradability, antimicrobial ability, and easy film forming ability. Different chitosan-based films have been fabricated and applied in the field of food packaging. Most of the review papers related to chitosan-based films are focusing on antibacterial food packaging films. Along with the advances in the nanotechnology and polymer science, numerous strategies, for instance direct casting, coating, dipping, layer-by-layer assembly, and extrusion, have been employed to prepare chitosan-based films with multiple functionalities. The emerging food packaging applications of chitosan-based films as antibacterial films, barrier films, and sensing films have achieved great developments. This article comprehensively reviews recent advances in the preparation and application of engineered chitosan-based films in food packaging fields.

An Overview of Chitosan Nanoparticles and Its Application in Non-Parenteral Drug Delivery

The focus of this review is to provide an overview of the chitosan based nanoparticles for various non-parenteral applications and also to put a spotlight on current research including sustained release and mucoadhesive chitosan dosage forms. Chitosan is a biodegradable, biocompatible polymer regarded as safe for human dietary use and approved for wound dressing applications. Chitosan has been used as a carrier in polymeric nanoparticles for drug delivery through various routes of administration. Chitosan has chemical functional groups that can be modified to achieve specific goals, making it a polymer with a tremendous range of potential applications. Nanoparticles (NP) prepared with chitosan and chitosan derivatives typically possess a positive surface charge and mucoadhesive properties such that can adhere to mucus membranes and release the drug payload in a sustained release manner. Chitosan-based NP have various applications in non-parenteral drug delivery for the treatment of cancer, gastrointestinal diseases, pulmonary diseases, drug delivery to the brain and ocular infections which will be exemplified in this review. Chitosan shows low toxicity both in vitro and some in vivo models. This review explores recent research on chitosan based NP for non-parenteral drug delivery, chitosan properties, modification, toxicity, pharmacokinetics and preclinical studies.

Dynamic Structuration of Physical Chitosan Hydrogels

We studied the microstructure of physical chitosan hydrogels formed by the neutralization of chitosan aqueous solutions highlighting the structural gradients within thick gels (up to a thickness of 16 mm). We explored a high polymer concentrations range (C_p ≥ 1.0% w/w) with different molar masses of chitosan and different concentrations of the coagulation agent. The effect of these processing parameters on the morphology was evaluated mainly through small-angle light scattering (SALS) measurements and confocal laser scanning microscopy (CLSM) observations. As a result, we reported that the microstructure is continuously evolving from the surface to the bulk, with mainly two structural transitions zones separating three types of hydrogels. The first zone (zone I) is located close to the surface of the hydrogel and constitutes a hard (entangled) layer formed under fast neutralization conditions. It is followed by a second zone (zone II) with a larger thickness (∼3-4 mm), where in some cases large pores or capillaries (diameter ∼10 μm) oriented parallel to the direction of the gel front are present. Deeper in the hydrogel (zone III), a finer oriented microstructure, with characteristic sizes lower than 2-3 μm, gradually replace the capillary morphology. However, this last bulk morphology cannot be regarded as structurally uniform because the size of small micrometer-range-oriented pores continuously increases as the distance to the surface of the hydrogel increases. These results could be rationalized through the effect of coagulation kinetics impacting the morphology obtained during neutralization.

Use of response surface methodology (RSM) to optimize pea starch-chitosan novel edible film formulation

The aim of this study was to develop an optimal formulation for preparation of edible films from chitosan, pea starch and glycerol using response surface methodology. Three independent variables were assigned comprising chitosan (1-2%), pea starch (0.5-1.5%) and glycerol (0.5-1%) to design an empirical model best fit in physical, mechanical and barrier attributes. Impacts of independent variables on thickness, moisture content, solubility, tensile strength, elastic modulus, elongation at break and water vapor permeability of films were evaluated. All the parameters were found to have significant effects on physical and mechanical properties of film. The optimal formulation for preparation of edible film from chitosan, pea starch and glycerol was 1% chitosan, 1.5% pea starch and 0.5% glycerol. Edible films with good physical and mechanical properties can be prepared with this formulation and thus this formulation can be further applied for testing on coating for fruit and vegetables.

Polysaccharides in Human Health Care

Polysaccharides are abundant natural polymers found in plants, animals and microorganisms with exceptional properties and essential roles to sustain life. They are well known for their high nutritive value and the positive effects on our immune and digestive functions and detoxification system. The knowledge and recognition of the important role they play for promoting and maintaining human health and wellbeing is continuously increasing. This review describes some important polysaccharides (e.g. mucilages and gums, glycosamine glycans and chitin/chitosan) and their medical, cosmetic and pharmaceutical applications, with emphasis on the relationship between structure and function. Next, the use of polysaccharides as nutraceuticals and vaccines is discussed in more detail. An analysis of the trends and challenges in polysaccharide research concludes the paper.

Composite poly(lactic acid)/chitosan nanofibrous scaffolds for cardiac tissue engineering

Fibrous scaffolds with different ratios of poly (lactic acid) (PLA) and chitosan were fabricated by conventional electrospinning. After crosslinking by the glutaraldehyde vapor, the structure, mechanical properties, hydrophilicity, and in-fiber chemical interactions of the scaffolds were investigated. We found that the fiber diameter decreased with the concentration of chitosan, while mechanical properties and hydrophilicity improved. In addition, we found that scaffolds with aligned fibers have higher mechanical strength and biocompatibility than scaffolds with randomly oriented fibers. In particular, scaffolds with aligned fibers with PLA:chitosan ratios of 7:1 was found to support cardiomyocyte viability, elicit cell elongation, and enhance production of sarcomeric α-actinin and troponin I. Collectively, the data indicate that composite scaffolds consisting of PLA/chitosan fibers have great potential for engineering cardiac tissue, and for accelerating the regeneration of myocardia.