Chitosan-Sodium Phytate Films with a Strong Water Barrier and Antimicrobial Properties Produced via One-Step-Consecutive-Stripping and Layer-by-Layer-Casting Technologies

Effects of eugenol on physicochemical properties of sturgeon skin collagen-chitosan composite membrane

In this study, a series of collagen-chitosan-eugenol (CO-CS-Eu) flow-casting composite films were prepared using collagen from sturgeon skin, chitosan, and eugenol. The physicochemical properties, mechanical properties, microstructure, as well as antioxidant and antimicrobial activities of the composite membranes were investigated by various characterization techniques. The findings revealed that the inclusion of eugenol augmented the thickness of the film, darkened its color, reduced the transparency, and enhanced the ultraviolet light-blocking capabilities, with the physicochemical properties of the CO-CS-0.25%Eu film being notably favorable. Eugenol generates increasingly intricate matrices that disperse within the system, thereby modifying the optical properties of the material. Furthermore, the tensile strength of the film decreased from 70.97 to 20.32 MPa, indicating that eugenol enhances the fluidity and ductility of the film. Added eugenol also exhibited structural impact by loosening the film cross-section and decreasing its density. The Fourier transform infrared spectroscopy results revealed the occurrence of several intermolecular interactions among collagen, chitosan, and eugenol. Moreover, the incorporation of eugenol bolstered the antioxidant and antimicrobial capabilities of the composite film. This is primarily attributed to the abundant phenolic/hydroxyl groups present in eugenol, which can react with free radicals by forming phenoxy groups and neutralizing hydroxyl groups. Consequently, inclusion of eugenol substantially enhances the freshness retention performance of the composite film. PRACTICAL APPLICATION: ● The CO-CS-Eu film utilizes collagen from sturgeon skin, improving the use of sturgeon resources.● Different concentrations of eugenol altered its synergistic effect with chitosan.● The CO-CS-Eu film is composed of natural products with safe and edible properties.

Sequential removal of phosphate and copper(II) ions using sustainable chitosan biosorbent

Although adsorbents are good candidates for removing phosphorus and heavy metals from wastewater, the use of biosorbents for the sequential treatment of phosphorus and copper has not yet been studied. Porous chitosan (CS)-based biosorbents (CGBs) were developed to adsorb phytic acid (PA), a major form of organic phosphate. This first adsorbate (PA) further served as an additional ligand (P-type ligand) for the CGBs (N-type ligand) to form a complex with the second adsorbate (copper). After the adsorption of PA (the first adsorbate), the spent CGBs were recycled and used as a new adsorbent to adsorb Cu(II) ions (the second adsorbate), which was expected to have a dual coordination effect through P, N-ligand complexation with copper. The interactions and complexation between CS, PA and Cu(II) ions on the PA-adsorbed CGBs (PACGBs) were investigated by performing FTIR, XPS, XRD, and SEM-EDS analyses. The PACGBs exhibited fast and enhanced adsorption of Cu(II) ions, owing to the synergistic effect of the amino groups of CS (the original ligand, N-type) and the phosphate groups of PA (an additional ligand, P-type) on the adsorption of Cu(II) ions. This is the first time that sequential removal of phosphorus and heavy metals by biosorbents has been performed using biosorbents.

Enhancement of mechanical and barrier properties of chitosan-based bionanocomposites films reinforced with eggshell-derived hydroxyapatite nanoparticles

In this study, Hydroxyapatite nanoparticles (HANPs), derived from eggshell waste, were employed to reinforce chitosan biopolymer-based films through the solvent-casting method. The impact of varying HANPs content (1%, 3%, 5%, and 10 wt %) in bionanocomposites was investigated. The influence of HANPs addition on the final film properties was comprehensively analyzed using Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), Dynamic Mechanical Analysis (DMA), mechanical (tensile) testing, and Water Vapor Permeability (WVP). The morphological aspects of bionanocomposites and the dispersion of nanoparticles within the matrix were studied using Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), and X-ray Diffraction (XRD). The structural changes in the films were probed using Fourier-Transform Infrared Spectroscopy (FTIR) and X-ray Photoelectron Spectroscopy (XPS) techniques. Results indicated that the addition of 1% and 3% of HANPs exhibited a higher glass transition temperature and improved thermal stability in bionanocomposites. Films with 3% HANPs content exhibited a notable increase in tensile strength, showing a 61.54% increase, while films with 1% HANPs content displayed a 52% reduction in WVP compared to pristine chitosan films. These findings underscore the significant potential of chitosan-hydroxyapatite bionanocomposite films for applications in food packaging applications.

ZnO nanoparticles coated and stearic acid modified superhydrophobic chitosan film for self-cleaning and oil-water separation

The aim of this study was to prepare superhydrophobic chitosan films using a ZnO nanoparticle coating and stearic acid hydrophobic modification. A 1 % concentration of ZnO nanoparticles and a 1 % concentration of stearic acid generated a superhydrophobic film with the largest contact angle (WCA) of 156°, which was attributed to the synergy of micro/nano-level hierarchical structure and low surface energy modification. The superhydrophobic film showed better stability to acid, alkali, heat, and UV irradiation than a neat chitosan film and a reduction in light transmittance of 14.4 % at 354 nm. The superhydrophobic chitosan film also showed excellent self-cleaning and oil-water separation performance. Our findings will expand the application of chitosan films in food packaging, outdoor self-cleaning materials and oil-water separations.

Polyelectrolyte-multivalent molecule complexes: physicochemical properties and applications

The complexation of polyelectrolytes with other oppositely charged structures gives rise to a great variety of functional materials with potential applications in a wide spectrum of technological fields. Depending on the assembly conditions, polyelectrolyte complexes can acquire different macroscopic configurations such as dense precipitates, nanosized colloids and liquid coacervates. In the past 50 years, much progress has been achieved to understand the principles behind the phase separation induced by the interaction of two oppositely charged polyelectrolytes in aqueous solutions, especially for symmetric systems (systems in which both polyions have similar molecular weight and concentration). However, in recent years, the complexation of polyelectrolytes with alternative building blocks such as small charged molecules (multivalent inorganic species, oligopeptides, and oligoamines, among others) has gained attention in different areas. In this review, we discuss the physicochemical characteristics of the complexes formed by polyelectrolytes and multivalent small molecules, putting a special emphasis on their similarities with the well-known polycation-polyanion complexes. In addition, we analyze the potential of these complexes to act as versatile functional platforms in various technological fields, such as biomedicine and advanced materials engineering.

Linear Dextrin as Potential Insulin Delivery System: Effect of Degree of Polymerization on the Physicochemical Properties of Linear Dextrin-Insulin Inclusion Complexes

In the current study, linear dextrin (LD) was prepared using waxy potato starch debranched with pullulanase, which has attracted immense interest in the food, pharmaceutical, and cosmetic industries as a versatile ingredient. Various LDs were separated on the basis of their differential solubility in aqueous/ethanol solutions of different volumetric ratios. Three LD products—LD Fabrications with 40% ethanol (F-40); LD Fabrications with 50% ethanol (F-50); and LD Fabrications with 60%, 70%, and 80% ethanol (F-M)—were obtained with an average degree of polymerization (DP) values of 31.44, 21.84, and 16.10, respectively. The results of Fourier transform infrared spectroscopy (FT-IR) analysis revealed that the reaction mainly involved hydrogen bonding and a hydrophobic interaction between LD and insulin in the process of inclusion complex formation. X-ray diffraction (XRD) results indicated that insulin was encapsulated in LD. The results of circular dichroism (CD) showed that the changes in the secondary structure of insulin were negligible during the release from the inclusion complexes. The order of encapsulation capacity is as follows: the complex composed of F-M and insulin (F-M-INS) > the complex composed of LD and insulin (LD-INS) > the complex composed of F-50 and insulin (F-50-INS) > and the complex composed of F-40 and insulin (F-40-INS). F-M-INS inclusion complexes showed a better effect on reducing the release of insulin in gastric juice and promoting the release of insulin in intestinal juice and blood plasma than LD-INS.

Recent advances in chitosan-based layer-by-layer biomaterials and their biomedical applications

In recent years, chitosan-based biomaterials have been continually and extensively researched by using layer-by-layer (LBL) assembly, due to their potentials in biomedicine. Various chitosan-based LBL materials have been newly developed and applied in different areas along with the development of technologies. This work reviews the recent advances of chitosan-based biomaterials produced by LBL assembly. Driving forces of LBL, for example electrostatic interactions, hydrogen bond as well as Schiff base linkage have been discussed. Various forms of chitosan-based LBL materials such as films/coatings, capsules and fibers have been reviewed. The applications of these biomaterials in the field of antimicrobial applications, drug delivery, wound dressings and tissue engineering have been comprehensively reviewed.

Preparation of a superhydrophilic SiO2 nanoparticles coated chitosan-sodium phytate film by a simple ethanol soaking process

The development of environmentally friendly and transparent superhydrophilic food packaging materials is essential in our daily lives. The objective of this study was to develop a simple method of preparing a superhydrophilic, transparent, and biodegradable composite film. The composite film was obtained by soaking a chitosan-sodium phytate film in an ethanol solution of SiO₂ nanoparticles. The results showed that when the chitosan-sodium phytate film was coated with SiO₂ nanoparticles that were dissolved in 75% ethanol, its water contact angle (WCA) was reduced from 100° to 3°, and the film surface was changed from a hydrophobic to a superhydrophilic. Furthermore, the oxygen transmission rate (OTR) was significantly reduced, and the mechanical properties of the film were improved. The method is easy to carry out and can be used for the potential production of superhydrophilic materials.

Innovative Polyelectrolyte Treatment to Flame-Retard Wood

Fire protection has been a major challenge in wood construction for many years, mainly due to the high flame spread risk associated with wood flooring. Wood fire-retardancy is framed by two main axes: coating and bulk impregnation. There is a growing need for economically and environmentally friendly alternatives. The study of polyelectrolyte complexes (PECs) for wood substrates is in its infancy, but PECs’ versatility and eco-friendly character are already recognized for fabric fire-retardancy fabrics. In this study, a new approach to PEC characterization is proposed. First, PECs, which consist of polyethyleneimine and sodium phytate, were chemically and thermally characterized to select the most promising systems. Then, yellow birch (Betula alleghaniensis Britt.) was surface-impregnated under reduced pressure with the two PECs identified as the best options. Overall, wood fire-retardancy was improved with a low weight gain of 2 wt.% without increasing water uptake.

Chitosan coating of zein-carboxymethylated short-chain amylose nanocomposites improves oral bioavailability of insulin in vitro and in vivo

Non-invasive means of insulin administration circumvent some of the inconveniences of injections. Oral administration in particular is convenient, pain-free, and allows favorable glucose homeostasis, but is subject to chemical instability, enzymatic degradation, and poor gastrointestinal absorption. Natural polymeric nanoparticles have emerged as a promising oral delivery system for peptide therapeutics due their safety, biocompatibility, and stability. In this study, self-assembled nanocomposites from chitosan (CS) and insulin-loaded, zein-carboxymethylated short-chain amylose (IN-Z-CSA) nanocomposites were synthesized to improve oral bioavailability of insulin. The optimized IN-Z-CSA/CS_0.2% nanocomposites exhibited an average size of 311.32±6.98 nm, a low polydispersity index (0.227±0.01), a negative zeta potential (43.77±1.36 mV), an encapsulation efficiency of 89.6±0.9%, and a loading capacity of 6.8±0.4%. The IN-Z-CSA/CS_0.2% nanocomposites were stable in storage conditions. The transepithelial permeability of the N-Z-CSA/CS_0.2% nanocomposites was 12-fold higher than that of insulin. Cellular uptake studies revealed that the IN-Z-CSA/CS_0.2% nanocomposites were internalized into Caco-2 cells by both endocytosis and a paracellular route. Additionally, in pharmacological studies, orally administered IN-Z-CSA/CS_0.2% nanocomposites had a stronger hypoglycemic effect with a relative bioavailability of 15.19% compared with that of IN-Z-CSA_1.0% nanocomposites. Furthermore, cell toxicity and in vivo tests revealed that the IN-Z-CSA/CS_0.2% nanocomposites were biocompatible. Overall, these results indicate that the IN-Z-CSA/CS_0.2% nanocomposites can improve oral bioavailability of insulin and are a promising delivery system for insulin or other peptide/protein drugs.

Influence of Nano Titanium Dioxide and Clove Oil on Chitosan-Starch Film Characteristics

The combined effects of nano titanium dioxide (TiO₂-N) and clove oil (CO) on the physico-chemical, biological and structural properties of chitosan (CH)/starch (ST) films were investigated by using a solvent casting method. Results indicated that the incorporation of TiO₂-N could improve the compactness of the film, increase the tensile strength (TS) and antioxidant activity, and decrease the water vapour permeability (WVP). As may be expected, the incorporation of CO into the film matrix decreased TS but increased the hydrophobicity as well as water vapour barrier antimicrobial and antioxidant properties. Fourier-transform infrared spectroscopy (FTIR) data supported intermolecular interactions between TiO₂-N, CO and the film matrix. Use of a scanning electron microscope (SEM) showed that TiO₂-N and CO were well dispersed and emulsified in the film network. Thermogravimetric (TG) and derivative thermogravimetric (DTG) curves demonstrated that TiO₂-N and CO were well embedded in the film matrix, hence this blend film system could provide new formulation options for food packaging materials in the future.

The thiolated chitosan: Synthesis, gelling and antibacterial capability

Chitosan-1-(mercaptomethyl)-cyclopropane acetic acid (CS-MCA) copolymer was synthesized by amino linkage. The obtained copolymer was characterized by FTIR, ¹H NMR, XRD, TGA and SEM. Porous and reticulate morphologies were found on the CS-MCA surface. The effects of pH on the rheological properties of CS-MCA were investigated. On the one hand, the apparent viscosity of CS-MCA indicated a shear-thinning behavior. The graft of MCA enhanced the moduli and the maximum elastic properties were observed at pH = 7.00. The addition of dithiothreitol reduced the viscosity and modulus of CS-MCA hydrogel, and the gelation time, temperature and frequency were obtained in dynamic oscillatory tests. The antibacterial effect of CS-MCA against E. coli was investigated for the inhibition zone and bacterial growth curve. These results showed that CS-MCA had better antibacterial ability than chitosan without modification. Therefore, the rheological behavior and functional activities can be applied for the hydrocolloid gels in food and pharmaceutical applications.

Preparation of Borax Cross-Linked Starch Nanoparticles for Improvement of Mechanical Properties of Maize Starch Films

Recently, starch nanoparticles have attracted widespread attention from various fields. In this study, a new strategy for preparing covalent-cross-linked starch nanoparticles was developed using boron ester bonds formed between debranched starch (DBS) and borax. The nanoparticles were characterized by Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), X-ray diffraction (XRD), dynamic light scattering (DLS), differential scanning calorimeter (DSC), and thermogravimetric analysis (TGA). The obtained nanoparticles were spherical with a size of 100-200 nm. The formation of boron ester bonds was confirmed by FTIR. The as-prepared starch nanoparticle exhibited a low relative crystallinity of 13.6%-23.5%. Compared with pure starch film, the tensile strength of starch film with 10% starch nanoparticles increased about 45%, and the elongation at break percentage of starch film with 5% starch nanoparticles increased about 20%. The new strategy of forming starch nanoparticles by using boron ester bonds will advance the research of carbohydrate nanoparticles.