κ-Carrageenan/poly(vinyl alcohol) functionalized films with gallic acid and stabilized with metallic ions.

Given the environmental issues caused by the extensive use of conventional petroleum-based packaging, this work proposes functional films based on commercial κ-carrageenan (κc), poly(vinyl alcohol) (PVA), and gallic acid (GA) prepared by the "casting" method. Metallic ions in the κc composition stabilized the films, supporting processability and suitable mechanical properties. However, the incorporated GA amount (6.25 and 10 wt%) in the films created from an aqueous κc solution at 3.0 % wt/v (κc3) prevented crystalline domains in the resulting materials. The κc3/GA6.25 and κc3/GA10 films had less tensile strength (8.50 ± 0.61 and 10.28 ± 0.65 MPa) and high elongation at break (2.36 ± 0.16 and 1.19 ± 0.17 %) compared to the other samples, respectively. Low κc contents (κc2.5/GA6.25 and κc2.5/GA10) promoted stiff films and less permeability to water vapor (5.36 ± 0.51 and 3.76 ± 0.02 [×10-12 g(Pa × m × s)-1], respectively. The κc/GA weight ratio also influenced the film wettability, indicating water contact angles (WCAs) between 55 and 74°. The surface wettability implies a low oil permeability and high water swelling capacity of up to 1600 %. The κc/GA also played an essential role in the film's antimicrobial action against Staphylococcus aureus and Escherichia coli. Thus, the κc3/GA10 film showed suitable physical, chemical, and biological properties, having the potential to be applied as food coatings.

Chitosan/gellan gum ratio content into blends modulates the scaffolding capacity of hydrogels on bone mesenchymal stem cells.

Here, we have demonstrated the production and characterization of hydrogel scaffolds based on chitosan/gellan gum (CS/GG) assemblies, without any covalent and metallic crosslinking agents, conventionally used to yield non-soluble polysaccharide-based materials. The polyelectrolyte complexes (physical hydrogels called as PECs) are characterized by Fourier-transform infrared spectroscopy, wide-angle X-ray scattering, and scanning electron microscopy. Hydrogels containing chitosan (CS) excesses (ranging from 60 to 80 wt%) were created. Durable polysaccharide-based scaffolds with structural homogeneity and interconnecting pore networks are developed by modulating the CS/GG weight ratio. The CS/GG hydrogel prepared at 80/20 CS/GG weight ratio (sample CS/GG80-20) is cytocompatible, supporting the attachment, growth, and spreading of bone marrow mesenchymal stem cells (BMSCs) after nine days of cell culture. The cytocompatibility is correlated to the swelling capacity of the PEC in PBS buffer (pH 7.4). By controlling the CS content, we can tune the water uptake of the material, enhancing the capacity to serve as a three-dimensional cell scaffold for BMSCs. This work presents for the first time that CS/GG hydrogels can be applied as scaffolds for tissue engineering purposes.

Poly(vinyl alcohol)/cationic tannin blend films with antioxidant and antimicrobial activities.

This study reports the synthesis, characterization and biological properties of films based on poly(vinyl alcohol) (PVA) and a cationic tannin polymer derivative (TN). Films are obtained from polymeric blends by tuning the PVA/TN weight ratios. The materials are characterized through infrared spectroscopy, X-ray photoelectron spectroscopy, contact angle measurements, mechanical analyses, and scanning electron microscopy. More hydrophilic surfaces are created by modulating the PVA and TN concentrations in the blends. Disintegration tests showed that the films present durability in phosphate buffer (pH 7.4) and low stability in simulated gastric fluid (pH 1.2). The film created at 90/10 PVA/TN weight ratio and crosslinked at 109 PVA/glutaraldehyde molar ratio (sample PVA10/TN10) supports the attachment and proliferation of bone marrow mesenchymal stem cells after 7 days of culture. The scaffolding capacity of the PVA10/TN10 surface is compared with titanium, one of the most important biomedical materials used in bone replacements. Also, the PVA/TN films exhibited cytocompatibility, antioxidant and antimicrobial activity against Staphylococcus aureus and Pseudomonas aeruginosa. These properties make PVA/TN films are candidates for biomedical applications in the tissue engineering field.