The development of electrospun chloramphenicol containing wound dressing

Abstract

Wound healing is among the most complex processes in the human body that is greatly coordinated with a focus to rebuild tissue integrity and restore the skin´s protective barrier. The normal healing process is disrupted in chronic wounds, leading to delayed wound healing due to several underlying factors such as aging, obesity, and diabetes. Among chronic wounds 50 % are infected and up to 78 % of these wounds have presence of biofilm. The management of these wounds is complicated, even with antibiotics. Antibiotic resistance is a growing issue worldwide. Thus, there is a need for innovative treatments that are capable of accelerating wound healing process, and at the same time, prevent and fight bacterial contamination and growth. Electrospinning is a favorable method for making nanofiber dressings. These nanofibers can be added several active ingredients to obtain multifunctional wound dressings.

This project aims as developing multifunctional nanofibers, containing the active ingredient soluble beta-1,3/1,6-glucan (SBG) with an immune stimulating effect, and chitosan (CHI) applied for its antimicrobial effect. In addition, we incorporated chloramphenicol (CAM) as the antimicrobial ingredient. Hydroxypropyl methylcellulose (HPMC) and polyethylene oxide (PEO) were used as co-polymers, and water, ethanol, and acetic acid were used as solvents. The focus of this master project was to process and characterize these multifunctional nanofiber formulations together with appropriate control formulations.

The nanofibers were produced using the needle-free NanospiderTM technology. To assess the properties of fabricated nanofibers, suitable methods for characterization of both polymer solutions without and with CAM and final nanofibers were applied. Conductivity, pH, surface tension and viscosity were examined to characterize the polymer solutions. The produced nanofibers were evaluated for absorption capacity, tensile properties, morphologies, and diameter. Fabricated nanofibers with CAM were evaluated for its content and in vitro release. In addition, all nanofibers were assessed for in vitro cell toxicity.

Polymer solutions containing CAM and -glucan (G) did not affect solution properties. CHI containing polymer solutions had increased conductivity, pH, and viscosity. The electrospinning process was not influenced by these increased properties. The temperature and relative humidity were successfully controlled during the electrospinning process for all nanofibers. All nanofibers were uniform and had diameter in the range from 129.5 to 200.9 nm. Nanofibers containing CHI did hold their structure in simulated wound fluid (SWF) and was possible to be investigated for absorption capacity. These nanofibers had absorption capacity up to 1055 % and was judged suitable for treatment of moderate to high exudative wounds. The method used for absorption capacity was not able to be performed on nanofibers without CHI since these nanofibers dissolved fast in SWF. The tensile strength of all produced nanofibers was in the skin range and proved to have good strength. However, the elongation at break for all nanofibers was poor and suggested to be less elasticity compared to the native skin. CHI and G nanofibers did not affect the in vitro CAM release, since all nanofibers had burst release of CAM. The high recovery of CAM from the in vitro CAM release, from 85 to 99 %, indicates that CAM is stable in all nanofibers and tolerate the electrospinning process well. Lastly, all nanofibers did not show cytotoxicity, indicating good cytocompatibility on human immortalized keratinocytes (HaCaT) cell lines.

Keywords: Chitosan; SBG; -glucan; Chloramphenicol; Nanofiber; Needle-free electrospinning; NanospiderTM; Wound dressing; Wound healing; Chronic wounds