Erythromycin Releasing PVA/sucrose and PVA/honey Hydrogels as Wound Dressings with Antibacterial Activity and Enhanced Bio-adhesion.

The present study deals with preparation and characterization of thermally crosslinked PVA-based hydrogels containing honey and sucrose for the purpose of erythromycin delivery. The hydrogels have been characterized and compared by scanning electron microscopy, Fourier transform infrared spectroscopy, and bio-adhesion tests. Swelling measurements showed that addition of sucrose and honey decreased the equilibrium swelling of the hydrogels. Results of release studies showed that the amount of erythromycin, released at the early hours was higher for PVA/sucrose and PVA/honey hydrogels compared to PVA hydrogel while the drug released at later times was highly reduced for PVA/honey hydrogel. Both Peppas-Sahlin and Korsmeyer-Peppas models fitted well to the release data. Fitting Peppas-Sahlin model to the release data showed that at the initial times, release of drug from the hydrogel network was mainly governed by Fickian mechanism; however, at later times the drug is dominantly released by relaxational mechanism due to swelling of the network,. Addition of honey improved the bio-adhesion of PVA/honey hydrogel as compared to PVA/sucrose and pure PVA hydrogel. Results of antibacterial tests showed growth inhibitory action of erythromycin-loaded PVA hydrogels against Pseudomonas aeruginosa and Staphylococcus aureus bacteria. This study indicates that these hybrid hydrogels are capable of being used as functional wound dressings aiming to control the rate of antibiotic delivery to the wound site and prevent the wounds from infection.

Fluorinated Methacrylamide Chitosan Hydrogel Dressings Improve Regenerated Wound Tissue Quality in Diabetic Wound Healing.

Objective: Oxygen therapy has shown promising results for treating diabetic wounds. However, clinically used oxygen therapies are cumbersome and expensive. Thus, there is a need to develop a localized oxygenating treatment that is easy to use and inexpensive. Approach: In this study, we tested a previously developed hydrogel sheet wound dressing based on fluorinated methacrylamide chitosan (MACF) for enhanced oxygenation and compared it with a commercial sheet hydrogel dressing, AquaDerm™, and no treatment controls in a splinted transgenic diabetic mouse wound model. Results: AquaDerm exhibited poor wound closure response compared with the MACF oxygenating hydrogel sheet dressing (MACF+O2) and no treatment. Histological analysis revealed enhanced collagen synthesis and neovascularization upon MACF+O2 treatment as indicated by higher collagen content and number of blood vessels/capillaries compared with AquaDerm and no treatment. MACF+O2 also improved wound collagen fiber alignment, thus demonstrating improved skin tissue maturation. Nuclear magnetic resonance spectroscopy-based biodistribution analysis revealed that the degradation products of the MACF-based dressing did not accumulate in lung, liver, and kidney tissues of the treated animals after 14 days of treatment. Innovation: This study presents the first application of a unique oxygenating biomaterial (MACF) made into a moist hydrogel wound dressing for treating diabetic wounds. Conclusion: The results of this study confirm the benefits of this novel biomaterial approach for improving regenerated tissue structure in diabetic wound healing.

Effect of Honey/PVA Hydrogel Loaded by Erythromycin on Full-Thickness Skin Wound Healing in Rats; Stereological Study.

BACKGROUND: Skin wounds are a significant public health risk, and treatment of wound remains a challenging clinical problem for medical teams and researchers. MATERIALS AND METHODS: In the present study, we aimed to investigate the healing effects of honey/polyvinyl alcohol (PVA) hydrogel loaded with erythromycin as wound dressing on skin wounds in rats, based on histological studies. In this study, 60 male Wistar rats, with a 1.5 ×1.5 cm2 diameter full-thickness wounds on the backs were divided into four groups: honey/PVA with the erythromycin hydrogel group, honey group, PVA group, and the control group, with no treatment. Skin biopsies were prepared at days 4, 7, and 14 for microscopic analyses. The stereological analysis, including the mean area of the wound, length of vessels, numerical density of fibroblast, macrophage, basal cell and volume of the epidermis, dermis, and fibrous tissue were performed. RESULTS: Wounds area in the honey/PVA hydrogel with the erythromycin group were significantly (P<0.05) smaller than in the other group. The numerical density of fibroblast, macrophage, basal cell and volume of the epidermis in the honey/PVA hydrogel with the erythromycin group were significantly higher than other groups. CONCLUSION: According to our results, honey/PVA hydrogel with erythromycin may promote early wound healing and has a positive influence on fibroblast proliferation and re-epithelialization, and its administration is recommended after further validation of clinical data.

Oxygen Regulation in Development: Lessons from Embryogenesis towards Tissue Engineering.

Oxygen is a vital source of energy necessary to sustain and complete embryonic development. Not only is oxygen the driving force for many cellular functions and metabolism, but it is also involved in regulating stem cell fate, morphogenesis, and organogenesis. Low oxygen levels are the naturally preferred microenvironment for most processes during early development and mainly drive proliferation. Later on, more oxygen and also nutrients are needed for organogenesis and morphogenesis. Therefore, it is critical to maintain oxygen levels within a narrow range as required during development. Modulating oxygen tensions is performed via oxygen homeostasis mainly through the function of hypoxia-inducible factors. Through the function of these factors, oxygen levels are sensed and regulated in different tissues, starting from their embryonic state to adult development. To be able to mimic this process in a tissue engineering setting, it is important to understand the role and levels of oxygen in each developmental stage, from embryonic stem cell differentiation to organogenesis and morphogenesis. Taking lessons from native tissue microenvironments, researchers have explored approaches to control oxygen tensions such as hemoglobin-based, perfluorocarbon-based, and oxygen-generating biomaterials, within synthetic tissue engineering scaffolds and organoids, with the aim of overcoming insufficient or nonuniform oxygen levels and nutrient supply.

Electrospinning of PVA/chitosan nanocomposite nanofibers containing gelatin nanoparticles as a dual drug delivery system.

Nanofibrous core-sheath nanocomposite dual drug delivery system based on poly(vinyl alcohol) (PVA)/chitosan/lidocaine hydrochloride loaded with gelatin nanoparticles were successfully prepared by the electrospinning method. Gelatin nanoparticles were prepared by nanoprecipitation and were then loaded with erythromycin antibiotic agent with the average particle size of ∼175 nm. The morphology of gelatin nanoparticles observed by field emission scanning electron microscopy (FE-SEM) was shown to be optimal at the concentration of 1.25 wt % of gelatin in aqueous phase by addition of 20 µL of glutaraldehyde 5% as the crosslinking agent. The nanoparticles were also characterized by dynamic light scattering, zeta potential measurement, and Fourier transform infrared spectroscopy (FTIR). The best bead free morphology for the PVA/chitosan nanofibrous mats were obtained at the solution weight ratio of 96/4. The nanofibrous mats were analyzed by swelling studies, FTIR and antibacterial tests. In vitro dual release profile of the core-sheath nanofibers was also studied within 72 h and showed the release efficiency equal to 84.69 and 75.13% for lidocaine hydrochloride and erythromycin, respectively. According to release exponent n, the release of lidocaine hydrochloride from the sheath part of the matrix is quasi-Fickian diffusion mechanism, while the release of erythromycin is based on anomalous or non-Fickian mechanisms.