Tuning the properties of alginate-chitosan membranes by varying the viscosity and the proportions of polymers

Honey-Loaded Reinforced Film Based on Bacterial Nanocellulose/Gelatin/Guar Gum as an Effective Antibacterial Wound Dressing

Recently, the use of bacterial nanocellulose (BNC) produced by Acetobacter, which has suitable properties for tissue engineering application as a perfect wound dressing, has attracted considerable attention. For this purpose, we successfully developed honey loaded BNC-reinforced gelatin/dialdehyde-modified guar gum films (H/BNC/Ge/D-GG). Prepared films were studied for their morphological, thermal stability, mechanical, water solubility and degradability properties. The physicochemical properties of the developed films with or without honey loading were studied. The results indicated that by enhancing the honey content of the film, the degradation behavior, adhesion and proliferation of NIH-3T3 fibroblast cells were improved. The films with 15 wt% of honey revealed inhibition activity against S. aureus (13.0±0.1 mm) and E. coli (15.0±1.0 mm) bacteria. Cell culture results demonstrated that the prepared films had good cytocompatibility. Based on the results, the prepared H/BNC/Ge/D-GG films appear to have high potential for antibacterial wound dressings.

Arabinoxylan-Carboxymethylcellulose Composite Films for Antibiotic Delivery to Infected Wounds

Modern dressings should provide for local delivery of antibiotics and protect the wound from bacterial infection, dehydration and environmental factors to achieve optimal healing. The local delivery of antibiotics can reduce adverse effects and resistance challenges. In this study, we fabricated film dressings composed of arabinoxylan (AX) from Plantago ovata seed husks and carboxymethylcellulose (CMC) by a solvent cast method for the delivery of the antibiotic amikacin (AMK). To determine the suitability of the prepared AX-CMC composite films as wound dressings and drug delivery materials, their physical, chemical, mechanical, morphological, thermal, pharmaceutical, antimicrobial, cytocompatible, and drug delivery properties were investigated. The results demonstrated that the dressings were suitable for delivering the drug at the wound site in a sustained manner and keeping the environment moist for rapid healing. The AMK-loaded AX-CMC films exhibited controlled release of AMK, excellent antibacterial activity, and cytocompatibility. Thus, the AX-CMC composite films appear to be promising bioactive dressing materials for the prevention of wound infections.

Prospection of chitosan and its derivatives in wound healing: Proof of patent analysis (2010-2020)

Disruption in the normal anatomy and physiology of the skin often leads to wound formation. Its healing is a pretty complex and dynamic biological process with different phases. While there are many biopolymers (and their derivatives) for wound healing purposes. One of the most popular, promising, progressive and attention-grabbing biopolymers is 'chitosan'. It is a polysaccharide biopolymer that has tremendous potential in augmenting the process of wound healing. Most importantly, the derivatives of chitosan have heavily attracted the scientific community's attention to employing them in various formulations for wound healing applications. The prime focus of the present review is to provide scientific and technological prospection about chitosan and its derivatives for wound healing activity, starting from 2010 to 2020. Besides, the review also focuses about toxicity, different formulations and products of chitosan that are currently under clinical trials for wound healing purposes are described. Through this review, we present evidence that abundantly confirms that there is a growing interest in the domain of wound healing using novel, inventive, useful and patent protected chitosan derivatives. We speculate the possibility of more patent protected chitosan derivatives in the future for wound healing applications.

Synthesis of Water Resistance and Moisture-Permeable Nanofiber Using Sodium Alginate-Functionalized Waterborne Polyurethane

The development of nontoxic and biodegradable alginate-based materials has been a continual goal in biological applications. However, their hydrophilic nature and lack of spinnability impart water instability and poor mechanical strength to the nanofiber. To overcome these limitations, sodium alginate (SA) and waterborne polyurethane (WPU) were blended and crosslinked with calcium chloride; 30 wt % of SA exhibited good compatibility. Further addition of 10 wt % calcium chloride improved the water stability to an extremely humid region. Furthermore, the stress-strain curve revealed that the initial modulus and the elongation strength of the WPU/SA and WPU/CA blends increased with SA content, and the crosslinker concentration clearly indicated the dressing material hardness resulted from this simple blend strategy. The WPU/SA30 electrospun nanofibrous blend contained porous membranes; it exhibited good mechanical strength with water-stable, water-absorbable (37.5 wt %), and moisture-permeable (25.1 g/m2-24 h) characteristics, suggesting our cost-effective material could function as an effective wound dressing material.

Flexible, dense and porous chitosan and alginate membranes containing the standardized extract of Arrabidaea chica Verlot for the treatment of skin lesions

The combination of chitosan (C) with alginate (A) has been explored for the production of dressings due to the positive results on wound healing. CA films can show a dense or porous flexible structure, with characteristics tunable for different applications. Porosity and flexibility can be achieved, respectively, by the addition of surfactants such as Kolliphor® P188 (P) and silicone-based compounds as Silpuran® 2130 A/B (S). Furthermore, composite matrices of these polysaccharides have potential applications as devices for releasing bioactive compounds to skin lesions. The purpose of this study was to evaluate the physicochemical and biological characteristics of flexible dense and porous CA membranes incorporating the standardized extract of Arrabidaea chica Verlot (A. chica), and also to analyze the release mechanism of the extract from different membrane formulations. The results show that the inclusion of P in the formulation allows obtaining porous matrices, promotes greater homogeneity of the mixture of the silicone gel with the suspension of polysaccharides, and increases the swelling of the polymer matrix. All formulations presented high stability, reaching a maximum mass loss of 18% after seven days. The formulations with S showed the best performance in terms of flexibility and strain at break. The presence of A. chica standardized extract did not affect negatively the characteristics of the membranes. Incorporation efficiencies of the bioactive compound above 87% were achieved, and the addition of P and S to the membrane formulation changed the release of the A. chica extract kinetics. In addition, the developed formulations did not significantly affect Vero cells proliferation.

Long lasting mucoadhesive membrane based on alginate and chitosan for intravaginal drug delivery

The intravaginal route of administration can be exploited to treat local diseases and for systemic delivery. In this work, we developed an alginate/chitosan membrane sufficiently stable in a simulated vaginal fluid and able to dissolve over time at a very slow and linear rate. The membrane demonstrated good mechanical properties both in its swollen and dry form. As a study case, we evaluated the viability of this potential drug delivery system for the treatment of bacterial vaginosis, a common disease affecting women in their reproductive age. Metronidazole was effectively included in the alginate/chitosan membrane and its bactericide effect was demonstrated against Staphylococcus aureus and Gardnerella vaginalis, simultaneously showing good biocompatibility with a cervix epithelial cell line. Since this alginate/chitosan membrane is stable in a simulated vaginal environment, is easy to fabricate and can be used for the controlled release of a model drug, it represents a promising drug delivery system for local intravaginal applications.

Polysaccharides for tissue engineering: Current landscape and future prospects

Biological studies on the importance of carbohydrate moieties in tissue engineering have incited a growing interest in the application of polysaccharides as scaffolds over the past two decades. This review provides a perspective of the recent approaches in developing polysaccharide scaffolds, with a focus on their chemical modification, structural versatility, and biological applicability. The current major limitations are assessed, including structural reproducibility, the narrow scope of polysaccharide modifications being applied, and the effective replication of the extracellular environment. Areas with opportunities for further development are addressed with an emphasis on the application of rationally designed polysaccharides and their importance in elucidating the molecular interactions necessary to properly design tissue engineering materials.

Effect of heat-transfer capability on micropore structure of freeze-drying alginate scaffold

Biodegradable porous scaffold is widely used in the field of tissue engineering. Scaffolds were required to have proper microstructure with suitable size, gradient, shape and porosity to mimic the specific three-dimensional structure of extracellular matrix. Taken the simple technique of freeze-drying, the nucleation and growth of ice crystals were affected by thermal behavior of solution during freezing process, which could be controlled to tailor and predict the pore structure in scaffold. This paper aimed to reveal the effect of containers' heat-transfer capability on the thermal behaviors of solution, and then its influence to pore structure in scaffold. Four containers with different heat transfer capacity were adopted for cooling model to achieve different thermal characterizations within solution during cooling process. The vertical cross-section of scaffold was observed by scanning electron microscopy. The porosity and tensile properties of scaffold were measured to depict scaffold characteristics. Scaffolds fabricated by containers with λ/d = 20,000, 3000 and 450 W/m²·°C showed cellular pores with gradient. With the decrease of λ/d, pores in scaffold were enlarged, and the wall between neighboring pores also became thicker. Pillared pores were produced only in container with λ/d = 50 W/m²·°C, oriented along the vertical direction without gradient. This process demonstrated that by altering the container of cooling model, scaffold microstructure could be tailored.

Preparation and Identification of Optimal Synthesis Conditions for a Novel Alkaline Anion-Exchange Membrane

The physicochemical and mechanical properties of new alkaline anion-exchange membranes (AAEMs) based on chitosan (CS) and poly(vinyl alcohol) (PVA) polymers doped with unsupported copper nanoparticles (NPs) and copper exchanged over different porous materials were investigated regarding ion-exchange capacity (IEC), OH⁻ conductivity, water uptake (WU), water vapor permeability (WVP), and thermal and mechanical resistance. The influence of the type of filler included in different morphologies and filler loading has been explored using copper exchanged materials such as the layered porous titanosilicate AM-4, layered stannosilicate UZAR-S3, and zeolites Y, MOR, and BEA. Compared to commercially available anion-exchange membranes, the best performing membranes in terms of WU, IEC, OH⁻ conductivity and WVP in this study were those containing 10 wt % of Cu-AM-4 and Cu-UZAR-S3, although 10 wt % Cu-MOR provided better mechanical strength at close values of WVP and anion conductivity. It was also observed that when Cu was exchanged in a porous silicate matrix, its oxidation state was lower than when embedded as unsupported metal NPs. In addition, the statistical analysis of variance determined that the electrochemical properties of the membranes were noticeably affected by both the type and filler loading, and influenced also by the copper oxidation state and content in the membrane, but their hydrophilic properties were more affected by the polymers. The largest significant effects were noticed on the water sorption and transport properties, which gives scope for the design of AAEMs for electrochemical and water treatment applications.

Polyelectrolyte complexes based on alginate/tanfloc: Optimization, characterization and medical application

Hydrogels based on alginate and tanfloc (a cationic biopolymer obtained from natural condensed tannins) were successfully prepared. Tanfloc (TN) presents high aqueous solubility at pHs lower than 10; it contains substituted amino sites and molar weight of ca. 600,000gmol^-1. A factorial design (2²) was used to optimize the yield of alginate/tanfloc polyelectrolyte complexes (PECs). Dialysis recovered the overplus of alginate (AG) no complexed with TN. These materials were characterized by thermal analyses (TGA/DTG and DSC), zeta potential, and FTIR, while SEM technique depicted a rough surface on AG/TN complex, containing non-homogeneous pores. Indeed, the AG and TN were tailored to elicit scaffold materials with outstanding cytocompatibility, mainly upon mouse preosteoblastic cells because of reconstruction of bone tissues (119% at 10days). The AG/TN complex also displayed antioxidant and bactericidal activities against Staphylococcus aureus (S. aureus). Besides, the pristine TN fostered bacteriostatic and bactericidal performances towards S. aureus and Escherichia coli. However, for our best knowledge, no studies were still carried out on TN and TN-based materials for medical purpose.