Control of the properties of porous chitosan–alginate membranes through the addition of different proportions of Pluronic F68

Chitosan Membranes Containing Plant Extracts: Preparation, Characterization and Antimicrobial Properties

The main strategy of this study was to combine the traditional perspective of using medicinal extracts with polymeric scaffolds manufactured by an engineering approach to fabricate a potential dressing product with antimicrobial properties. Thus, chitosan-based membranes containing S. officinalis and H. perforatum extracts were developed and their suitability as novel dressing materials was investigated. The morphology of the chitosan-based films was assessed by scanning electron microscopy (SEM) and the chemical structure characterization was performed via Fourier transform infrared spectroscopy (FTIR). The addition of the plant extracts increased the sorption capacity of the studied fluids, mainly at the membrane with S. officinalis extract. The membranes with 4% chitosan embedded with both plant extracts maintained their integrity after being immersed for 14 days in incubation media, especially in PBS. The antibacterial activities were determined by the modified Kirby-Bauer disk diffusion method for Gram-positive (S. aureus ATCC 25923, MRSA ATCC 43300) and Gram-negative (E. coli ATCC 25922, P. aeruginosa ATCC 27853) microorganisms. The antibacterial property was enhanced by incorporating the plant extracts into chitosan films. The outcome of the study reveals that the obtained chitosan-based membranes are promising candidates to be used as a wound dressing due to their good physico-chemical and antimicrobial properties.

Classification and Production of Polymeric Foams among the Systems for Wound Treatment

This work represents an overview on types of wounds according to their definition, classification and dressing treatments. Natural and synthetic polymeric wound dressings types have been analyzed, providing a historical overview, from ancient to modern times. Currently, there is a wide choice of materials for the treatment of wounds, such as hydrocolloids, polyurethane and alginate patches, wafers, hydrogels and semi-permeable film dressings. These systems are often loaded with drugs such as antibiotics for the simultaneous delivery of drugs to prevent or cure infections caused by the exposition of blood vessel to open air. Among the presented techniques, a focus on foams has been provided, describing the most diffused branded products and their chemical, physical, biological and mechanical properties. Conventional and high-pressure methods for the production of foams for wound dressing are also analyzed in this work, with a proposed comparison in terms of process steps, efficiency and removal of solvent residue. Case studies, in vivo tests and models have been reported to identify the real applications of the produced foams.

Influence of replacing oregano essential oil by ground oregano leaves on chitosan/alginate-based dressings properties

Biopolymers, as chitosan and alginate, have gained prominence in the biomedical area, mainly for application in wound dressings, as partial replacements for synthetic polymers. The present work aimed to compare the influence of the antimicrobial agent incorporation form on the properties of films prepared by casting. The chitosan/alginate-based films were manufactured containing oregano essential oil (OEO) or ground oregano leaves (OR). The OEO was chosen due to its excellent pharmacological properties, and the substitution by OR can represent an advantageous alternative for minimizing the final cost of the product, by removing the oil extraction step. The films, with different amounts of OEO and OR, were characterized in terms of their morphological, physicochemical, mechanical and antimicrobial properties. The films had properties according to desirable for wound dressing application: water vapor flux less than 35 g m^-2 h^-1, moderate liquid absorption capacity, and similar mechanical properties to human skin. All developed films showed antimicrobial activity against the bacteria Escherichia coli and Staphylococcus aureus. Formulations containing OEO presented the largest inhibition zones, although OR showed high potential for the proposed use. These results suggest that films developed, with both OEO and ground oregano leaves, are promising for use as dressings.

A competitive nature-derived multilayered scaffold based on chitosan and alginate, for full-thickness wound healing

The aim of this study was to evaluate a bioactive multilayer wound dressing, based on chitosan and alginate. To enhance healing potential, Dracaena Cinnabari and Aloe Vera were loaded as separate layers into the scaffold. The bare and bioactive multilayered scaffolds were fabricated by an iterative layering freeze-drying technique. Following of topographical, chemical, and physical assessment, the performance of the scaffolds was evaluated in vitro and in vivo. The results revealed adequate attachment, and proliferation of human foreskin fibroblasts, indicating excellent biocompatibility of the bioactive scaffold. In vivo, the performance of the multi-layered scaffold loaded with the bioactive materials was comparable with Comfeel plus®. The wounds treated with the bioactive scaffold exhibited superior hypergranulation, fibroblast maturation, epithelization, and collagen deposition, with minimal inflammation, and crust formation. It is concluded that the synergism of extracellular matrix-mimicking multi-layered scaffolding with Aloe Vera and Dracaena Cinnabari could be considered as a supportive wound dressing.

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.

Alginate-based composite materials for wound dressing application:A mini review

Alginate biopolymer has been used in the design and development of several wound dressing materials in order to improve the efficiency of wound healing. Mainly, alginate improves the hydrophilic nature of wound dressing materials in order to create the required moist wound environment, remove wound exudate and increase the speed of skin recovery of the wound. In addition, alginate can easily cross-link with other organic and inorganic materials and they can promote wound healing in clinical applications. This review article addresses the importance of alginates and the roles of derivative polymeric materials in wound dressing biomaterials. Additionally, studies on recent alginate-based wound dressing materials are discussed.

Production, Preparation and Characterization of Microalgae-Based Biopolymer as a Potential Bioactive Film

Six microalgae strains were screened according to their biomass productivity and polymer synthesis, showing biomass productivity between 0.14 and 0.68 g/(L·d) for a 21-day growth period. Extracellular biopolymers from the spent culture media of Nostoc sp. (No), Synechocystis sp. (Sy), and Porphyridium purpureum (Pp) was obtained, and the yields of the clean biopolymer were 323, 204, and 83 mg/L, respectively. The crude biopolymer was cleaned up using a solid-phase extraction technique. The emulsification index E24 values for the clean biopolymer were 77.5%, 68.8%, and 73.3% at 0.323, 0.083, and 0.204 mg/mL, respectively. The clean biopolymer of the No strain showed the highest fungal growth inhibition against Fusarium verticillioides (70.2%) and Fusarium sp. (61.4%) at 2.24 mg/mL. In general, transparent and flexible biofilms were prepared using biopolymers of No and Pp. The microstructural analysis revealed the presence of pores and cracks in the biofilms, and the average roughness Ra values are 68.6 and 86.4 nm for No and Pp, respectively, and the root mean square roughness Rq values are 86.2 and 107.2 nm for No and Pp, respectively.

Polysaccharide-based tissue-engineered vascular patches

Coronary artery and peripheral vascular diseases are the leading cause of morbidity and mortality worldwide and often require surgical intervention to replace damaged blood vessels, including the use of vascular patches in endarterectomy procedures. Tissue engineering approaches can be used to obtain biocompatible and biodegradable materials directed to this application. In this work, dense or porous scaffolds constituted of chitosan (Ch) complexed with alginate (A) or pectin (P) were fabricated and characterized considering their application as tissue-engineered vascular patches. Scaffolds fabricated with alginate presented higher culture medium uptake capacity (up to 17 g/g) than materials produced with pectin. A degradation study of the patches in the presence of lysozyme showed longer-term stability for Ch-P-based scaffolds. Pectin-containing matrices presented higher elastic modulus (around 280 kPa) and ability to withstand larger deformations. Moreover, these materials demonstrated better performance when tested for hemocompatibility, with lower levels of platelet adhesion and activation. Human smooth muscle cells (HSMC) adhered, spread and proliferated better on matrices produced with pectin, probably as a consequence of cell response to higher stiffness of this material. Thus, the outcomes of this study demonstrate that Ch-P-based scaffolds present superior characteristics for the application as vascular patches. Despite polysaccharides are yet underrated in this field, this work shows that biocompatible tridimensional structures based on these polymers present high potential to be applied for the reconstruction and regeneration of vascular tissues.

Morphology and performance of polyvinyl chloride membrane modified with Pluronic F127

Background: Attempts to modify the morphology of membrane for application in industrial separation are being undertaken by many researchers. The present study discusses the morphological modification of polyvinyl chloride (PVC) membrane by combining the hydrophilic surfactant Pluronic F127 (PF127) in a polymer solution to improve the performance of the membrane.  Method: The membrane is formed using the non-solvent induced-phase separation (NIPS) method. PF127 is added to the membrane solution as a membrane modifying agent. The effects of the surfactant concentration in the dope solution on the permeability of pure water, solute rejection, hydrophilic characteristics, and membrane morphology are investigated. Results: Higher concentrations of PF127 had a significant effect on the permeability of pure water. The highest membrane permeation was 45.65 l/m 2.hr.atm with the addition of 7% PF127 additive. Conclusion: PF127 is successfully proposed as a membrane pore-forming agent in this work; the blending of this additive in appropriate amounts in the polymer solution is adequate to improve the performance of the PVC membrane.

Morphology and performance of polyvinyl chloride membrane modified with Pluronic F127

Background: Attempts to modify the morphology of membrane for application in industrial separation are being undertaken by many researchers. The present study discusses the morphological modification of polyvinyl chloride (PVC) membrane by combining the hydrophilic surfactant Pluronic F127 (PF127) in a polymer solution to improve the performance of the membrane.  Method: The membrane is formed using the non-solvent induced-phase separation (NIPS) method. PF127 is added to the membrane solution as a membrane modifying agent. The effects of the surfactant concentration in the dope solution on the permeability of pure water, solute rejection, hydrophilic characteristics, and membrane morphology are investigated. Results: Higher concentrations of PF127 had a significant effect on the permeability of pure water. The highest membrane permeation was 45.65 l/m 2.hr.atm with the addition of 7% PF127 additive. Conclusion: PF127 is successfully proposed as a membrane pore-forming agent in this work; the blending of this additive in appropriate amounts in the polymer solution is adequate to improve the performance of the PVC membrane.

Release Behavior and Antibacterial Activity of Chitosan/Alginate Blends with Aloe vera and Silver Nanoparticles

Aloe vera is a perennial plant employed for medical, pharmaceutical and cosmetic purposes that is rich in amino acids, enzymes, vitamins and polysaccharides, which are responsible for its therapeutic properties. Incorporating these properties into a biopolymer film obtained from alginate and chitosan allowed the development of a novel wound dressing with antibacterial capacity and healing effects to integrate the antibacterial capacity of silver nanoparticles with the healing and emollient properties of Aloe vera gel. Three alginate-chitosan matrices were obtained through blending methods using different proportions of alginate, chitosan, the Aloe vera (AV) gel and silver nanoparticles (AgNps), which were incorporated into the polymeric system through immersion methods. Physical, chemical and antibacterial characteristics were evaluated in each matrix. Interaction between alginate and chitosan was identified using the Fourier transform infrared spectroscopy technique (FTIR), porosity was studied using scanning electron microscopy (SEM), swelling degree was calculated by difference in weight, Aloe vera gel release capacity was estimated by applying a drug model (Peppas) and finally antibacterial capacity was evaluated against S. Aureus and P. aeruginosa. Results show that alginate-chitosan (A (1:3 Chit 1/Alg 1); B (1:3 Chit 1.5/Alg 1) and C (3:1 Chit 1/Alg 1/B12)) matrices with Aloe vera (AV) gel and silver nanoparticles (AgNps) described here displayed antibacterial properties and absorption and Aloe vera release capacity making it a potential wound dressing for minor injuries.

Preparation and Characterization of Chitosan-Agarose Composite Films

Nowadays, there is a growing interest to develop biodegradable functional composite materials for food packaging and biomedicine applications from renewable sources. Some composite films were prepared by the casting method using chitosan (CS) and agarose (AG) in different mass ratios. The composite films were analyzed for physical-chemical-mechanical properties including tensile strength (TS), elongation-at-break (EB), water vapor transmission rate (WVTR), swelling ratio, Fourier-transform infrared spectroscopy, and morphology observations. The antibacterial properties of the composite films were also evaluated. The obtained results reveal that an addition of AG in varied proportions to a CS solution leads to an enhancement of the composite film's tensile strength, elongation-at-break, and water vapor transmission rate. The composite film with an agarose mass concentration of 60% was of the highest water uptake capacity. These improvements can be explained by the chemical structures of the new composite films, which contain hydrogen bonding interactions between the chitosan and agarose as shown by Fourier-transform infrared spectroscopy (FTIR) analysis and the micro-pore structures as observed with optical microscopes and scanning electron microscopy (SEM). The antibacterial results demonstrated that the films with agarose mass concentrations ranging from 0% to 60% possessed antibacterial properties. These results indicate that these composite films, especially the composite film with an agarose mass concentration of 60%, exhibit excellent potential to be used in food packaging and biomedical materials.