Antibacterial and Antifungal Properties of Modified Chitosan Nonwovens

Preparation and characterization of carboxymethylated pullulan/butyric acid-modified chitosan active sustainable bi-layer coatings intended for packaging of cheese slices

Dependence of the food industry on conventional plastic and the generation of enormous amounts of food waste caused by microbiological spoilage have been imposed as inspiration for this work, to develop active sustainable packaging for sliced cheese using the bi-layer design. Pullulan was modified using a green approach to obtain a polyanionic character in the coating formulation. Chitosan, which has a cationic character in an acidic environment, has been modified using a butyric acid to obtain an amphiphilic character. The formed active bi-layer has demonstrated an improved barrier (decreased permeability for moisture vapor 72.2 and 77.7 times) and mechanical properties (increased tensile strength value up to 3.9 and 9.4 times) compared to the monolayer films. A novel approach to microbiological control of sliced cheese has been established, which implies a synergistic effect of Helichrysum italicum essential oil (EO) and corresponding hydrolate (HY) incorporated in separated layers. This design has ensured avoiding surfactants and preserving cheese's sensory properties, prolonging its shelf-life by 50 % at least. Improvements in cheese storage conditions using this packaging lie in the improved barrier, mechanical and antimicrobial properties, the order of lamination, and a good covering of the cheese surface by spraying.

Bactericidal Chitosan Derivatives and Their Superabsorbent Blends with ĸ-Carrageenan

The aim of this work is research dedicated to the search for new bactericidal systems for use in cosmetic formulations, dermocosmetics, or the production of wound dressings. Over the last two decades, chitosan, due to its special biological activity, has become a highly indispensable biopolymer with very wide application possibilities. Reports in the literature on the antibacterial effects of chitosan are very diverse, but our research has shown that they can be successfully improved through chemical modification. Therefore, in this study, results on the synthesis of new chitosan-based Schiff bases, dCsSB-SFD and dCsSB-PCA, are obtained using two aldehydes: sodium 4-formylbenzene-1,3-disulfonate (SFD) and 2-pyridine carboxaldehyde (PCA), respectively. Chitosan derivatives synthesized in this way demonstrate stronger antimicrobial activity. Carrying out the procedure of grafting chitosan with a caproyl chain allowed obtaining compatible blends of chitosan derivatives with κ-carrageenan, which are stable hydrogels with a high swelling coefficient. Furthermore, the covalently bounded poly(ε-caprolactone) (PCL) chain improved the solubility of obtained polymers in organic solvents. In this respect, the Schiff base-containing polymers obtained in this study, with special hydrogel and antimicrobial properties, are very promising materials for potential use as a controlled-release formulation of both hydrophilic and hydrophobic drugs in cosmetic products for skin health.

Enhancing Chitosan Fibers: A Dual Approach with Tripolyphosphate and Ursolic Acid

Chitosan, a well-established biomaterial known for its biocompatibility, biodegradability, and bioactivity, has been the focus of extensive research in recent years. This study explores the enhancement of chitosan fibers' properties through wet impregnation with either ursolic acid (UA) or cross-linking with tripolyphosphate (TPP). In the first experiment, chitosan fibers were treated with UA, for varying immersion set points (1, 2, 4, 6, and 8 h). FTIR, SEM, and UV-Vis spectroscopy analyses demonstrated a chemical reaction between chitosan and UA, with stability reached after 2 h of immersion. Antibacterial testing revealed that chitosan fibers impregnated with UA exhibited significant antibacterial activity against Gram-positive bacteria, notably Staphylococcus aureus. The second experiment involved modifying chitosan fibers' surfaces with a 1% w/v TPP solution for the same periods of time (1, 2, 4, 6, and 8 h). Subsequently, the investigation involved FTIR, SEM, and dynamometry analyses, which revealed successful cross-linking between chitosan and TPP ions, resulting in improved tensile strength after 2 h of immersion. This dual-approach study highlights the potential of chitosan fibers for diverse applications, from wound-healing dressings to antibacterial materials against Gram-positive bacteria.

Antibacterial potentials of carbon dots immobilized on chitosan and glass surfaces

Due to their antibacterial activity, chitosan‑carbon dot composites possess great potential for pharmaceuticals, medicine, and food preservation. Conducting a comprehensive study of the interactions between chitosan, carbon dots, and bacteria is crucial to understanding the processes behind applying these composites. This study aimed to immobilize carbon dots (C-dots) synthesized from Elaeagnus angustifolia fruits on chitosan and glass microbeads' surfaces, to characterize the test materials obtained after synthesis and immobilization, and to investigate their antibacterial potentials. C-dot synthesis was carried out from water extract in an acidic medium with the help of microwave irradiation, and their structural and optical properties were characterized by TEM, XRD, FT-IR, UV-vis, Zeta potential, and fluorescence methods. The surface of the glass microbeads was first activated and functionalized with surface amine groups with a silaning agent. C-dots were immobilized on both glass and chitosan microbeads using a crosslinking agent. Antibacterial potentials of nine different test materials, obtained before or after immobilization, were evaluated both qualitatively (MIC and MBC) and quantitatively (GI50) on E. coli, S. typhimurium, B. subtilis, and S. aureus, with the standard broth microdilution method. FT-IR and SEM-EDX analyses showed that C-dots were immobilized on chitosan (˂1 mm) and glass (˂100 μm) microbead surfaces. C-dots reduced the cell viability by ~25 % on S. typhimurium and B. subtilis (MIC = 25 mg/mL). It was also found that the highest antibacterial effect was recorded for C-dots-glass microbeads, which had a toxic effect of 43 % on S. aureus. In addition, binding C-dots to glass microbeads increased the antibacterial effect selectively in Gram-positive bacteria, while binding to chitosan microbeads was effective in all bacteria. The study showed that the antibacterial potential of C-dots-chitosan microbeads is more effective than C-dots-glass microbeads. C-dots could be used as carbon-based nanomaterials in antibacterial surface preparation once immobilized.

Synthesis and Characterization of Antibacterial Chitosan Films with Ciprofloxacin in Acidic Conditions

This work presents the results of research on obtaining chitosan (CS) films containing on their surface ciprofloxacin (CIP). A unique structure was obtained that not only gives new properties to the films, but also changes the way of coverage and structure of the surface. The spectroscopic test showed that in the process of application of CIP on the surface of CS film, CIP was converted from its crystalline form to an amorphic one, hence improving its bioavailability. This improved its scope of microbiological effect. The research was carried out on the reduction of CIP concentration during the process of CIP adhesion to the surface of chitosan films. The antibacterial activity of the CS films with and without the drug was evaluated in relation to Escherichia coli and Staphylococcus aureus, as well as Candida albicans and Penicillium expansum. Changes in the morphology and roughness of membrane surfaces after the antibacterial molecule adhesion process were tested with atomic force microscopy (AFM) and scanning electron microscopy (SEM). Structural analysis of CS and its modifications were confirmed with Fourier-transform spectroscopy in the infrared by an attenuated total reflectance of IR radiation (FTIR-ATR) and solid-state nuclear magnetic resonance (NMR).

Preparation and Characterization of a Biodegradable Film Using Irradiated Chitosan Incorporated with Lysozyme and Carrageenan and Its Application in Crayfish Preservation

In this study, a composite film was prepared using irradiated chitosan, lysozyme, and carrageenan for crayfish preservation. First, the chitosan was degraded by gamma rays, with the best antimicrobial properties being found at 100 KGy. By using the response surface method, the components of the composite film were irradiated chitosan (CS) at 0.016 g/mL, lysozyme (LM) at 0.0015 g/mL, and carrageenan (CA) at 0.002 g/mL. When compared to the natural chitosan film, the Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) results demonstrated that the chemical properties of the composite film did not change with the addition of LM and CA, while the physical and antibacterial properties increased, including tensile strength (16.87 → 20.28 N), hydrophobicity (67.9 → 86.3°), and oxygen permeability (31.66 → 24.31 m³·um/m²·day·kPa). Moreover, the antibacterial activity of the films increased with the addition of LM and CA, especially for Shewanella putrefaciens: the zone of inhibition (mm) of CS, CS/LM, and CS/LM/CA was 9.97 ± 0.29, 14.32 ± 0.31, and 14.78 ± 0.21, respectively. Finally, the CS/LM/CA film could preserve crayfish for 10 days at 4 °C, whereas the polyethylene (PE) film could only preserve them for 6 days. Moreover, the composite film was excellent at inhibiting oxidative deterioration (TBARS value: 2.12 mg/kg, day10) and keeping the texture of crayfish muscle. Overall, our results suggested that the CS/LM/CA composite film produced can be applied as a biodegradable film in aquatic product packaging.

Chitosan Biguanidine/PVP Antibacterial Coatings for Perishable Fruits

World hunger is on the rise, yet one-third of food is wasted. It is necessary to develop an effective food preservation method to reduce food waste. This article reports a composite film based on chitosan biguanidine hydrochloride(CBg) and poly (N-vinyl-2-pyrrolidone)(PVP) that can be used as a conformal coating for fresh produce. Due to the strong positive charge of CBg, the film has excellent antibacterial properties. Owing to the hydrogen bonds between CBg and PVP, the film has good flexibility and mechanical properties. In addition, the coating is washable, transparent, and can reduce the evaporation of water. The above characteristics mean the film has broad application prospects in the field of food preservation.

A Review on Antibacterial Biomaterials in Biomedical Applications: From Materials Perspective to Bioinks Design

In tissue engineering, three-dimensional (3D) printing is an emerging approach to producing functioning tissue constructs to repair wounds and repair or replace sick tissue/organs. It allows for precise control of materials and other components in the tissue constructs in an automated way, potentially permitting great throughput production. An ink made using one or multiple biomaterials can be 3D printed into tissue constructs by the printing process; though promising in tissue engineering, the printed constructs have also been reported to have the ability to lead to the emergence of unforeseen illnesses and failure due to biomaterial-related infections. Numerous approaches and/or strategies have been developed to combat biomaterial-related infections, and among them, natural biomaterials, surface treatment of biomaterials, and incorporating inorganic agents have been widely employed for the construct fabrication by 3D printing. Despite various attempts to synthesize and/or optimize the inks for 3D printing, the incidence of infection in the implanted tissue constructs remains one of the most significant issues. For the first time, here we present an overview of inks with antibacterial properties for 3D printing, focusing on the principles and strategies to accomplish biomaterials with anti-infective properties, and the synthesis of metallic ion-containing ink, chitosan-containing inks, and other antibacterial inks. Related discussions regarding the mechanics of biofilm formation and antibacterial performance are also presented, along with future perspectives of the importance of developing printable inks.