Characterization of chitosan composites with synthetic polymers and inorganic additives

Insights into chitosan-based cellulose nanowhiskers reinforced nanocomposite material via deep eutectic solvent in green chemistry

In the present work, the synthesis of cellulose nanowhiskers (CNW)/chitosan nanocomposite films via deep eutectic solvents (DES) changing the chemical structures were carried out. It was observed that a pure chitosan film has broadband at 3180-3400 cm^-1, indicating amide and hydroxyl groups. Upon CNW incorporation, the peak gets sharper and stronger and shifts to a greater wavelength. Further, the addition of DES infuses more elements of amide into the nanocomposite films. Moreover, the mechanical properties incorporating CNW filler into a chitosan matrix show an enhancement in tensile strength (TS), Young's modulus (YM), and elongation at break. The TS and YM increase while the elongation decrease as the CNW concentration increases. The YM of biocomposite films is increased to 723 MPa at 25% CNW into chitosan films. Besides, the TS has enhanced to 11.48 MPa at 15% CNW concentration in the biocomposite films. The elongation at break has decreased to 11.7% at 25% CNW concentration. Hence, incorporating CNW into the chitosan matrix via DES can still improve the mechanical properties of the nanocomposite films. Therefore, the application of DES results in a lower YM and TS as the films are hygroscopic. In conclusion, DES can be considered the new green solvent media for synthesizing materials. It has the potential to replace ionic liquids due to its biodegradability and non-toxic properties while preserving the character of low-vapour pressure. Besides that, chitosan can be used as potential material for applications in process industries, such as the biomedical and pharmaceutical industries. Thus, DES can be used as a green solvent and aim to reduce the toxic effect of chemicals on the environment during chemical production.

Rheological and Film-Forming Properties of Chitosan Composites

Chitosan (Chit) and its composite films are widely used in biomedical, cosmetic, and packaging applications. In addition, their properties can be improved and modified using various techniques. In this study, the effect of the type of clay in Chit composites on the structure, morphology, and physical properties of Chit solution and films was tested. The liquid flow properties of Chit solution with and without clay were carried out using the steady shear test. Chit films containing clay were obtained using the solution-casting method. The morphology, structure, and physical properties of the films were characterized by scanning electron microscopy, atomic force microscopy, infrared spectroscopy, swelling behavior, and tensile tests. The results reveal that for the Chit solution with clay (C1) containing 35 wt.% dimethyl dialkyl (C14-C18) amine, the apparent viscosity is the highest, whereas Chit solutions with other clays show reduced apparent viscosity. Rheological parameters of Chit composites were determined by the power law and Cross models, indicating shear-thinning behavior. Analytical data were compared, and show that the addition of clay is favorable to the formation of intermolecular interactions between Chit and clay, which improves in the properties of the studied composites.

Incorporation of Fluorescent Fluorinated Methacrylate Nano-Sized Particles into Chitosan Matrix Formed as a Membranes or Beads

Fluorescent particles are of particular interest as probes and active agents for biomedical, pharmaceutical, and food applications. Here, we present two strategies for incorporation of core-shell acrylic fluorescent nanoparticles (NPs) with Rhodamine B (RhB) as a dye into a chitosan (CS) matrix. We selected two variants of NPsRhB immobilisation in a CS membrane and biopolymeric CS beads. Modification of the method for production of the biopolymer cover/transporter of nanoparticles allowed two series of hydrogels loaded with nanoparticles to be obtained with a similar concentration of the aqueous solution of the nanoparticles. Microscopic analysis showed that the NPs were nonuniformly distributed in millimetre-sized CS beads, as well as membranes, but the fluorescence signal was strong. The composition of CS layers loaded with nanoparticles (CS/NPsRhB) showed water vapour barrier properties, characterised by the contact angle of 71.8°. Finally, we incorporated NPsRhBCS beads into a gelatine matrix to check their stability. The results confirmed good stability of the NPsRhBCS complex system, and no dye leakage was observed from the beads and the membranes. The proposed complex system demonstrated promising potential for further use in bioimaging and, thus, for the development of advanced diagnostic tools.

Natural-Fiber-Reinforced Chitosan, Chitosan Blends and Their Nanocomposites for Various Advanced Applications

There has been much effort to provide eco-friendly and biodegradable materials for the next generation of composite products owing to global environmental concerns and increased awareness of renewable green resources. This review article uniquely highlights the use of green composites from natural fiber, particularly with regard to the development and characterization of chitosan, natural-fiber-reinforced chitosan biopolymer, chitosan blends, and chitosan nanocomposites. Natural fiber composites have a number of advantages such as durability, low cost, low weight, high specific strength, non-abrasiveness, equitably good mechanical properties, environmental friendliness, and biodegradability. Findings revealed that chitosan is a natural fiber that falls to the animal fiber category. As it has a biomaterial form, chitosan can be presented as hydrogels, sponges, film, and porous membrane. There are different processing methods in the preparation of chitosan composites such as solution and solvent casting, dipping and spray coating, freeze casting and drying, layer-by-layer preparation, and extrusion. It was also reported that the developed chitosan-based composites possess high thermal stability, as well as good chemical and physical properties. In these regards, chitosan-based "green" composites have wide applicability and potential in the industry of biomedicine, cosmetology, papermaking, wastewater treatment, agriculture, and pharmaceuticals.

Preparation of new bio-based chitosan/Fe2O3/NiFe2O4 as an efficient removal of methyl green from aqueous solution

Modified chitosan with various functional groups has high potential as an efficient adsorbent in removing water pollution. In this study, new magnetic adsorbent, bio-based chitosan/Fe2O3/NiFe2O4, was successfully prepared by green chemistry route involving mixing of chitosan as core moiety and Fe2O3/NiFe2O4 nanocomposite, and slow evaporation of solvent. Synthesized chitosan/Fe2O3/NiFe2O4 was characterized by FT-IR, TGA, XRD, VSM and FE-SEM. The FT-IR and XRD results confirmed that the successful preparation of chitosan/Fe2O3/NiFe2O4. Uniform dispersion of Fe2O3/NiFe2O4 nanoparticles with low aggregation was confirmed by FE-SEM. The as-prepared magnetic chitosan/Fe2O3/NiFe2O4 was developed as solid phase adsorbent to remove methyl green (MG) dye from aqueous solutions. Several important parameters such as contact time, pH, temperature and adsorbent dosage were investigated systematically. The high and fast MG dye removal (≈ 80%) occurs after 30 min. The optimal conditions for MG removal was recorded at pH = 8, contact time of 60 min, adsorbent dosage of 0.2 g and 25 °C and displayed a high MG dye removal percentage of 96.51% and adsorption capacity of 77.22 mg/g.

Novel chitosan-poly(vinyl acetate) biomaterial suitable for additive manufacturing and bone tissue engineering applications

Chitosan, a biocompatible and biodegradable natural polymer, offers great promise as a biomaterial for tissue engineering applications. Chitosan scaffolds have previously been fabricated using additive manufacturing techniques, however, the use of crosslinkers, weak mechanical stability and structural resolution remain problematic. In this study Chitosan-PVAc biopolymer blends were prepared using a non-organic solvent that can prepare a three-dimensional printable biopolymer in less time than conventional methods. Prepared films were characterised using SEM, FTIR and thermogravimetric analysis. Additionally, the swelling properties, biodegradability and printability of the scaffolds were also studied. The fabricated films were biodegradable within a 3-week period and showed controllable swelling properties. Results indicated no toxicity and cells attached onto films. Additionally, hydrogels showed antibacterial activity against S. aureus, S. epidermidis and E.coli, which could potentially prevent implant related infections. Additive manufacturing simulation of PVAc composite 3% chitosan and PVAc composite 4% chitosan were able to produce a layered scaffold without using crosslinkers and therefore confirming printability. Cytocompabability were assessed using a resazurin assay and cell attachment. From these results, we concluded that the printable PVAc composite 3% chitosan and PVAc composite 4% chitosan biopolymer blends meet the requirements of a biomaterial and can potentially be used for biomedical implants.

Cationic chitosan derivatives as potential antifungals: A review of structural optimization and applications

The increasing resistance of pathogen fungi poses a global public concern. There are several limitations in current antifungals, including few available fungicides, severe toxicity of some fungicides, and drug resistance. Therefore, there is an urgent need to develop new antifungals with novel targets. Chitosan has been recognized as a potential antifungal substance due to its good biocompatibility, biodegradability, non-toxicity, and availability in abundance, but its applications are hampered by the low charge density results in low solubility at physiological pH. It is believed that enhancing the positive charge density of chitosan may be the most effective approach to improve both its solubility and antifungal activity. Hence, this review mainly focuses on the structural optimization strategy of cationic chitosan and the potential antifungal applications. This review also assesses and comments on the challenges, shortcomings, and prospect of cationic chitosan derivatives as antifungal therapy.

Antibacterial Films Based on PVA and PVA-Chitosan Modified with Poly(Hexamethylene Guanidine)

In this study, thin, polymeric films consisting of poly(vinyl alcohol) (PVA) and chitosan (Ch) with the addition of poly(hexamethylene guanidine) (PHMG) were successfully prepared. The obtained materials were analyzed to determine their physicochemical and biocidal properties. In order to confirm the structure of PHMG, nuclear magnetic resonance spectroscopy (1H NMR) was applied, while in the case of the obtained films, attenuated total reflectance infrared spectroscopy with Fourier transform (FTIR-ATR) was used. The surface morphology of the polymer films was evaluated based on atomic force microscopy. Furthermore, the mechanical properties, color changes, and thermal stability of the obtained materials were determined. Microbiological tests were performed to evaluate the biocidal properties of the new materials with and without the addition of PHMG. These analyses confirmed the biocidal potential of films modified by PHMG and allowed for comparisons of their physicochemical properties with the properties of native films. In summary, films consisting of PVA and PHMG displayed higher antimicrobial potentials against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria in comparison to PVA:Ch-based films with the addition of PHMG.

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.

Sorptive removal of Remazol Brilliant Blue R from aqueous solution by diethylenetriamine functionalized magnetic macro-reticular hybrid material

Chitosan, glycidyl methacrylate (synthetic polymer) and magnetite are combined to produce novel magnetic macro-reticular hybrid synthetic–natural materials which are shown to be effective sorbents for RBBR ions.