Pullulan-Based Hydrogels in Wound Healing and Skin Tissue Engineering Applications: A Review.

Wound healing is a complex process of overlapping phases with the primary aim of the creation of new tissues and restoring their anatomical functions. Wound dressings are fabricated to protect the wound and accelerate the healing process. Biomaterials used to design dressing of wounds could be natural or synthetic as well as the combination of both materials. Polysaccharide polymers have been used to fabricate wound dressings. The applications of biopolymers, such as chitin, gelatin, pullulan, and chitosan, have greatly expanded in the biomedical field due to their non-toxic, antibacterial, biocompatible, hemostatic, and nonimmunogenic properties. Most of these polymers have been used in the form of foams, films, sponges, and fibers in drug carrier devices, skin tissue scaffolds, and wound dressings. Currently, special focus has been directed towards the fabrication of wound dressings based on synthesized hydrogels using natural polymers. The high-water retention capacity of hydrogels makes them potent candidates for wound dressings as they provide a moist environment in the wound and remove excess wound fluid, thereby accelerating wound healing. The incorporation of pullulan with different, naturally occurring polymers, such as chitosan, in wound dressings is currently attracting much attention due to the antimicrobial, antioxidant and nonimmunogenic properties. Despite the valuable properties of pullulan, it also has some limitations, such as poor mechanical properties and high cost. However, these properties are improved by blending it with different polymers. Additionally, more investigations are required to obtain pullulan derivatives with suitable properties in high quality wound dressings and tissue engineering applications. This review summarizes the properties and wound dressing applications of naturally occurring pullulan, then examines it in combination with other biocompatible polymers, such chitosan and gelatin, and discusses the facile approaches for oxidative modification of pullulan.

Influence of Thermal Treatment and Acetic Acid Concentration on the Electroactive Properties of Chitosan/PVA-Based Micro- and Nanofibers.

This study presents, for the first time, a comprehensive investigation of the influence of pre- and post-fabrication parameters for the electroactive properties of electrospun chitosan/PVA-based micro- and nanofibers. Chitosan/PVA fibers were fabricated using electrospinning, characterized, and tested as electroactive materials. Solutions with different acetic acid contents (50, 60, 70, and 80 v/v%) were used, and the rheological properties of the solutions were analyzed. Characterization techniques, such as rheology, conductivity, optical microscopy, a thermogravimetric analysis, differential scanning calorimetry, a tensile test, and FT-IR spectroscopy, were utilized. Fiber mats from the various solutions were thermally treated, and their electroactive behavior was examined under a constant electric potential (10 V) at different pHs (2-13). The results showed that fibers electrospun from 80% acetic acid had a lower electroactive response and dissolved quickly. However, thermal treatment improved the stability and electroactive response of all fiber samples, particularly the ones spun with 80% acetic acid, which exhibited a significant increase in speed displacement from 0 cm-1 (non-thermally treated) to 1.372 cm-1 (thermally treated) at a pH of 3. This study sheds light on the influence of pre- and post-fabrication parameters on the electroactive properties of chitosan/PVA fibers, offering valuable insights for the development of electroactive materials in various applications.

Method of manufacturing and staining microplastics for using in the biological experiments.

Nowadays, plastic pollution attracts much attention both from society and scientists. The plastic pollution impact on the environment and human health requires assessment urgently, especially through experimental studies. However, such studies are still scarce because of the lack of standard methods for assessing their effects on living organisms. We have developed a process for manufacturing and staining PVC microparticles for using them in biological and ecological experiments. The electrospinning method has been used to manufacture PVC particles; their morphology and size have been analyzed. The obtained PVC particles are of narrow size range averaging 2-4 µm in diameter. They are successfully stained with the fluorescent dye Rhodamine B, which stands for the experiments performed in the seawater.

A Review on Chitosan and Cellulose Hydrogels for Wound Dressings.

Wound management remains a challenging issue around the world, although a lot of wound dressing materials have been produced for the treatment of chronic and acute wounds. Wound healing is a highly dynamic and complex regulatory process that involves four principal integrated phases, including hemostasis, inflammation, proliferation, and remodeling. Chronic non-healing wounds are wounds that heal significantly more slowly, fail to progress to all the phases of the normal wound healing process, and are usually stalled at the inflammatory phase. These wounds cause a lot of challenges to patients, such as severe emotional and physical stress and generate a considerable financial burden on patients and the general public healthcare system. It has been reported that about 1-2% of the global population suffers from chronic non-healing wounds during their lifetime in developed nations. Traditional wound dressings are dry, and therefore cannot provide moist environment for wound healing and do not possess antibacterial properties. Wound dressings that are currently used consist of bandages, films, foams, patches and hydrogels. Currently, hydrogels are gaining much attention as a result of their water-holding capacity, providing a moist wound-healing milieu. Chitosan is a biopolymer that has gained a lot of attention recently in the pharmaceutical industry due to its unique chemical and antibacterial nature. However, with its poor mechanical properties, chitosan is incorporated with other biopolymers, such as the cellulose of desirable biocompatibility, at the same time having the improved mechanical and physical properties of the hydrogels. This review focuses on the study of biopolymers, such as cellulose and chitosan hydrogels, for wound treatment.

High-Porosity Polymer Composite for Removing Oil Spills in Cold Regions.

In this work, polyvinyl chloride (PVC)/clay nanofiber composites with various contents were fabricated by the electrospinning process. The morphology, porosity, density, and mechanical properties of the nanofiber mats were investigated. In addition, PVC/clay nanofiber mats were characterized by Fourier transform infrared spectroscopy, differential scanning calorimetry, and thermogravimetric analysis. Moreover, the influence of the clay content in the nanofiber mats and its effect on oil sorption capacity were also evaluated. The results show that the clay particle diameter affects the fabrication, morphology, porosity, density, mechanical properties, and sorption capacity of the nanofiber mats. Adding clay in nanofiber composite materials leads to higher porosity and a higher oil sorption capacity. PVC/clay nanofiber mats have a high oil sorption capacity at low temperatures. They exhibit a high potential to be used as materials to eliminate oil spills under arctic conditions.