Development of chitosan/montmorillonite nanocomposites with encapsulated α-tocopherol

Incorporation of montmorillonite into microfluidics-generated chitosan microfibers enhances neuron-like PC12 cells for application in neural tissue engineering

The complexity in structure and function of the nervous system, as well as its slow rate of regeneration, makes it more difficult to treat it compared to other tissues. Neural tissue engineering aims to create an appropriate environment for nerve cell proliferation and differentiation. Fibrous scaffolds with suitable morphology and topography and better mimicry of the extracellular matrix have been promising for the alignment and migration of neural cells. On this premise, to improve the properties of the scaffold, we combined montmorillonite (MMT) with chitosan (CS) polymer and created microfibers with variable diameters and varied concentrations of MMT using microfluidic technology and tested its suitability for the rat pheochromocytoma cell line (PC12). According to the findings, CS/MMT 0.1 % compared to CS/MMT 0 % microfibers showed a 201 MPa increase in Young's modulus, a 68 mS/m increase in conductivity, and a 1.4-fold increase in output voltage. Analysis of cell mitochondrial activity verified the non-toxicity, resulting in good cell morphology with orientation along the microfiber. Overall, the results of this project showed that with a low concentration of MMT, the properties of microfibers can be significantly improved and a suitable scaffold can be designed for neural tissue engineering.

Nanocomposite Film Development Based on Chitosan/Polyvinyl Alcohol Using ZnO@montmorillonite and ZnO@Halloysite Hybrid Nanostructures for Active Food Packaging Applications

The global turn from the linear to the circular economy imposes changes in common activities such as food packaging. The use of biodegradable materials such as polyvinyl alcohol, natural raw materials such as clays, and food byproducts such as chitosan to develop novel food packaging films attracts the interest of industrial and institutional research centers. In this study, novel hybrid nanostructures were synthesized via the growth of zinc oxide nanorods on the surface of two nanoclays. The obtained nanostructures were incorporated with chitosan/polyvinyl alcohol composite either as nanoreinforcement or as an active agent to develop packaging films. The developed films were characterized via XRD, FTIR, mechanical, water-vapor diffusion, water sorption, and oxygen permeability measurements. Antimicrobial activity measurements were carried out against four different pathogen microorganisms. XRD indicated the formation of an intercalated nanocomposite structure for both types of nanoclays. Furthermore, improved tensile, water/oxygen barrier, and antimicrobial properties were recorded for all films compared to the pure chitosan/polyvinyl alcohol film. Overall, the results indicated that the use of the bio-based developed films led to an extension of food shelf life and could be used as novel active food packaging materials. Among them, the most promising film was the 6% wt. ZnO@halloysite.

Strategies to Improve the Barrier and Mechanical Properties of Pectin Films for Food Packaging: Comparing Nanocomposites with Bilayers

Traditional food packaging systems help reduce food wastage, but they also produce environmental impacts when not properly disposed of. Bio-based polymers are a promising solution to overcome these impacts, but they have poor barrier and mechanical properties. This work evaluates two strategies to improve these properties in pectin films: the incorporation of cellulose nanocrystals (CNC) or sodium montmorillonite (MMT) nanoparticles, and an additional layer of chitosan (i.e., a bilayer film). The bionanocomposites and bilayer films were characterized in terms of optical, morphological, hygroscopic, mechanical and barrier properties. The inclusion of the nanofillers in the polymer reduced the water vapor permeability and the hydrophilicity of the films without compromising their visual properties (i.e., their transparency). However, the nanoparticles did not substantially improve the mechanical properties of the bionanocomposites. Regarding the bilayer films, FTIR and contact angle studies revealed no surface and/or chemical modifications, confirming only physical coating/lamination between the two polymers. These bilayer films exhibited a dense homogenous structure, with intermediate optical and hygroscopic properties. An additional layer of chitosan did not improve the mechanical, water vapor and oxygen barrier properties of the pectin films. However, this additional layer made the material more hydrophobic, which may play an important role in the application of pectin as a food packaging material.

Preparation and Characterization of Bio-Nanocomposites Film of Chitosan and Montmorillonite Incorporated with Ginger Essential Oil and Its Application in Chilled Beef Preservation

In this study, bio-nanocomposite films containing different proportions of ginger essential oil (GEO), chitosan (Ch), and montmorillonite (MMT) were prepared and characterized, and the antibacterial effect of bio-nanocomposite films on chilled beef was evaluated. Fourier transform infrared analysis showed a series of intense interactions among the components of the bio-nanocomposite films. The infiltration of GEO increased the thickness of the film, reduced the tensile strength of the film, and increased the percentage of breaking elongation and the water vapor permeability. The migration of phenols in the films began to increase exponentially and reached equilibrium at about 48 h. The bio-nanocomposite films (Ch +0.5% GEO group, and Ch + MMT + 0.5% GEO group) effectively delayed the rise of pH, hue angle, and moisture values of chilled beef with time and slowed down the lipid oxidation and the growth of surface microorganisms on chilled beef. Altogether, the prepared biological nanocomposites can be used as promising materials to replace commercial and non-degradable plastic films.

Understanding the Barrier and Mechanical Behavior of Different Nanofillers in Chitosan Films for Food Packaging

The continuous petroleum-based plastics manufacturing generates disposal issues, spreading the problem of plastic pollution and its rise in the environment. Recently, innovative techniques and scientific research promoted biopolymers as the primary alternative for traditional plastics, raising and expanding global bioplastic production. Due to its unmatched biological and functional attributes, chitosan (Ch) has been substantially explored and employed as a biopolymeric matrix. Nevertheless, the hydrophilicity and the weak mechanical properties associated with this biopolymer represent a significant intrinsic restriction to its implementation into some commercial applications, namely, in food packaging industries. Distinct methodologies have been utilized to upgrade the mechanical and barrier properties of Ch, such as using organic or inorganic nanofillers, crosslinkers, or blends with other polymers. This review intends to analyze the most recent works that combine the action of different nanoparticle types with Ch films to reinforce their mechanical and barrier properties.

Active coatings of thermoplastic starch and chitosan with alpha-tocopherol/bentonite for special green coffee beans

The quality of green coffee beans (GCBs) is possibly affected by storage conditions. Edible polymer coatings for GCBs can help preserve flavors and improve shelf life of GCBs. This study aimed to incorporate α-tocopherol, a powerful antioxidant, in thermoplastic starch [TPS] and chitosan [TPC] and determined the best cavitation energy (960-3840 J·mL-1) using an ultrasonic probe. Then, we evaluated the incorporation of bentonite (0% and 2% m/m) and α-tocopherol (0% and 10% m/m) in the best energy cavitation/biopolymer combination. The TPS and TPC coatings demonstrated good adherence to the GCBs, measured by surface energy. The dispersion of α-tocopherol in TPC, with cavitation energy 960 J·mL-1, promoted greater stability (greater zeta potential), thereby increasing antioxidant activity by 28% compared to TPS, therefore, was selected for a second stage. Incorporation of 2% bentonite into the TPC, with 10% α-tocopherol, resulted in a 3.7 × 10-10 g·m-1·s-1·Pa-1 water vapor permeability, which is satisfactory for prevented of moisture gain during storage. The compressive load showed values of 375 N to the non-coated GCB and around 475 N with the insertion of coatings to the GCB. Thus, a TPC/α-tocopherol/bentonite combination, dispersed with 960 J·mL-1 energy, was highly effective in the development of biopolymeric coatings for the GCBs.

Physical and Morphological Characterization of Chitosan/Montmorillonite Films Incorporated with Ginger Essential Oil

Novel bionanocomposite films of chitosan/montmorillonite (CS/MMT) activated with ginger essential oil (GEO) were produced and characterized in terms of their physical and morphological properties. The homogenization process led to a good interaction between the chitosan and the nanoparticles, however the exfoliation was diminished when GEO was incorporated. Film glass transition temperature did not statistically change with the incorporation of either MMT or GEO, however the value was slightly reduced, representing a relaxation in the polymer chain which corroborated with the mechanical and barrier properties results. Pristine chitosan films showed excellent barrier properties to oxygen with a permeability of 0.184 × 10−16 mol/m·s·Pa being reduced to half (0.098 × 10−16 mol/m·s·Pa) when MMT was incorporated. Although the incorporation of GEO increased the permeability values to 0.325 × 10−16 mol/m·s·Pa when 2% of GEO was integrated, this increment was smaller with both MMT and GEO (0.285 × 10−16 mol/m·s·Pa). Bionanocomposites also increased the UV light barrier. Thus, the produced bioplastics demonstrated their ability to retard oxidative processes due to their good barrier properties, corroborating previous results that have shown their potential in the preservation of foods with high unsaturated fat content.

Shelf Life Assessment of Fresh Poultry Meat Packaged in Novel Bionanocomposite of Chitosan/Montmorillonite Incorporated with Ginger Essential Oil

Active packaging incorporated with natural extracts is a promising technology to extend shelf life of perishable food. Therefore, this study aimed to produce a bionanocomposite based on chitosan reinforced with sodium montmorillonite (MMT) and incorporated with ginger essential oil (GEO). In vitro activity was assessed through migration assay and antimicrobial study against foodborne bacteria. Phenolic compounds were diffused within 48 h of contact, and retained some of their antioxidant activity. Films demonstrated antimicrobial activity against both Gram-positive and -negative bacteria tested. The effect on the shelf life of fresh poultry meat was determined on samples wrapped in the biopolymers and stored under refrigeration for 15 days, through physicochemical and microbiological analyses. Compared to unwrapped poultry meat, samples wrapped in the bionanocomposites showed a reduction in microorganisms count of 1.2–2.6 log CFU/g, maintained color and pH values and thiobarbituric acid reactive substances (TBARS) index increased at a lower rate, extending fresh poultry meat shelf life. The incorporation of GEO enhanced the biopolymer activity, by reducing lipid oxidation and microbiological growth of the poultry meat. In contrast, reinforcement with MMT imprisoned the active compounds in the polymeric chain, hindering its activity. In conclusion, the bionanocomposites tested represent promising substitutes to commercial and unsustainable plastic films.

Characterization of chitosan-nanoclay bionanocomposite active films containing milk thistle extract

Nowadays, bio-based and antioxidant active packaging is attracting significant attention as one of the preferred emerging technologies to prevent sensitive oxidation of foods. In this study, chitosan/nanoclay nanocomposite active films containing three different levels of sodium montmorillonite (MMT) (1, 3 and 5% w/w based on chitosan) and Silybum marianum L. extract (SME) (0.5, 1 and 1.5% v/v) were prepared. The obtained films were characterized in terms of structural, thermal, mechanical, and barrier properties as well as antioxidant behavior. X-ray diffraction patterns confirmed the exfoliated dispersion form of MMT nanolayers. Scanning electron microscopy images showed an increase in films' surface roughness by the addition of MMT. The results indicated that water vapor permeability and solubility of films reduced significantly (p<0.05) by incorporation of MMT and SME. The mechanical and optical properties of films were significantly affected by the content of MMT and SME (p<0.05). Antioxidant properties of the films also were improved by SME incorporation, suggesting that the formulated bionanocomposites could be considered as a promising antioxidant active packaging material.

Novel chitosan-based/montmorillonite/palladium hybrid microspheres as heterogeneous catalyst for Sonogashira reactions

The objective of this study was to develop novel chitosan-based/montmorillonite/palladium (CS/MMT/Pd) hybrid microsphere catalysts with improved properties for use in Sonogashira reactions.

Use of herbs, spices and their bioactive compounds in active food packaging

Natural additives obtained from herbs and spices are being increasingly used in the food packaging industry.