Composite Wound Dressing Based on Chitin/Chitosan Nanofibers: Processing and Biomedical Applications

An electrospinning technique was used for the preparation of a bilayered wound dressing consisting of a layer of aliphatic copolyamide nanofibers and a layer of composite nanofibers from chitosan and chitin nanofibrils filler. Processed dressings were compared with aliphatic copolyamide nanofiber-based wound dressings and control groups. Experimental studies (in vivo treatment of third-degree burns with this dressing) demonstrated that almost complete (up to 97.8%) epithelialization of the wound surface had been achieved within 28 days. Planimetric assessment demonstrated a significant acceleration of the wound healing process. Histological analysis of scar tissue indicated the presence of a significant number of microvessels and a low number of infiltrate cells. In the target group, there were no deaths or purulent complications, whereas in the control group these occurred in 25% and 59.7% of cases, respectively—and, in the copolyamide group, 0% and 11%, respectively. The obtained data show the high efficiency of application of the developed composite chitosan‒copolyamide wound dressings for the treatment of burn wounds

Bacterial Cellulose-Based Nanocomposites Containing Ceria and Their Use in the Process of Stem Cell Proliferation

A technique for the fabrication of bacterial cellulose-based films with CeO2 nanofiller has been developed. The structural and morphological characteristics of the materials have been studied, their thermal and mechanical properties in dry and swollen states having been determined. The preparation methodology makes it possible to obtain composites with a uniform distribution of nanoparticles. The catalytic effect of ceria, regarding the thermal oxidative destruction of cellulose, has been confirmed by TGA and DTA methods. An increase in CeO2 content led to an increase in the elastic modulus (a 1.27-fold increase caused by the introduction of 5 wt.% of the nanofiller into the polymer) and strength of the films. This effect is explained by the formation of additional links between polymer macro-chains via the nanoparticles’ surface. The materials fabricated were characterized by a limited ability to swell in water. Swelling caused a 20- to 30-fold reduction in the stiffness of the material, the mechanical properties of the films in a swollen state remaining germane to their practical use. The application of the composite films in cell engineering as substrates for the stem cells’ proliferation has been studied. The increase in CeO2 content in the films enhanced the proliferative activity of embryonic mouse stem cells. The cells cultured on the scaffold containing 5 wt.% of ceria demonstrated increased cell survival and migration activity. An analysis of gene expression confirmed improved cultivation conditions on CeO2-containing scaffolds

Crystal and Supramolecular Structure of Bacterial Cellulose Hydrolyzed by Cellobiohydrolase from Scytalidium Candidum 3C: A Basis for Development of Biodegradable Wound Dressings

The crystal and supramolecular structure of the bacterial cellulose (BC) has been studied at different stages of cellobiohydrolase hydrolysis using various physical and microscopic methods. Enzymatic hydrolysis significantly affected the crystal and supramolecular structure of native BC, in which the 3D polymer network consisted of nanoribbons with a thickness T ≈ 8 nm and a width W ≈ 50 nm, and with a developed specific surface SBET ≈ 260 m2·g−1. Biodegradation for 24 h led to a ten percent decrease in the mean crystal size Dhkl of BC, to two-fold increase in the sizes of nanoribbons, and in the specific surface area SBET up to ≈ 100 m2·g−1. Atomic force and scanning electron microscopy images showed BC microstructure “loosening“after enzymatic treatment, as well as the formation and accumulation of submicron particles in the cells of the 3D polymer network. Experiments in vitro and in vivo did not reveal cytotoxic effect by the enzyme addition to BC dressings and showed a generally positive influence on the treatment of extensive III-degree burns, significantly accelerating wound healing in rats. Thus, in our opinion, the results obtained can serve as a basis for further development of effective biodegradable dressings for wound healin