Production of functional nanofibrous gelatin wound dressings and a study on drug repositioning

Abstract

Skin, a vital organ, consists of three parts: Epidermis, Dermis and Hypodermis. It is the largest organ and covers the entire outer surface of the body, serving as a barrier that protects organs and tissues. This thesis covers the healing of skin wounds with a novel wound dressing. The wound healing process occurs in 4 stages: Hemostasis, inflammatory, proliferation and remodeling. Wound dressings are biomaterials that can contribute to wound healing in different morphologies, mimic extracellular matrix, and become functional and developing day by day. The use of functionalized polymeric nanofibers in wound dressings is widespread. Nanofiber wound dressings, which contain bioactive substances and release those substances into the wound area, can be obtained from natural or synthetic polymers. There are various systems to produce nanofibers: electrospinning, centrifugal spinning, and solution blowing are among the most commonly used methods.In this thesis functional nanofiber wound dressings were produced from a mixture of gelatin, hyaluronic acid, and Atovaquone (ATQ). Gelatin, the by-product of collagen hydrolysis, is a water-soluble, non-toxic, biocompatible biopolymer that promotes cell proliferation. Gelatin, which is found in the cartilage, skin and bones of animals, is generally obtained from pig skin with a rate of 46%, followed by bovine with 29.4%. Hyaluronic acid (HA) is a natural anionic polysaccharide composed of repeating units of glucuronic acid and N-acetylglucosamine. The optimum nanofibers were obtained by applying a temperature of 100°C to the air coming to the nozzle to evaporate the water, since the solvent of the gelatin nanofibers produced in this thesis is v/v%80 water. ATQ was used for a drug repositioning intention to investigate its effects on wound healing. Drug repositioning technology has advantages such as acceptance of projects at earlier stages. ATQ also known as Malarone or Mepron, is an anti-parasitic and FDA-approved antimalarial drug. Optimization studies were performed according to obtained SEM images. In the first of productions, optimum nanofibers were obtained by applying a temperature of 100 °C to the air fed to the nozzle, at a feeding rate of 4 ml/h and 2 bar air pressure, with a volume ratio of 30% gelatin solvents by weight to v/v%80:20 distilled water: acetic acid. In subsequent optimizations, the gelatin ratio was reduced to 20% due to the high viscosity of HA and 0.5 grams of HA was added to the solution. In these processes, HA is first dissolved in water and then gelatin and acetic acid are added because HA is a water-soluble biopolymer that tends to agglomerate in acetic acid. Nanofibers were tested in vitro. According to MTT, the fact that there were no significant differences between the other groups and the control group and the cell viability is high (range 82-92%) means that the nanofibers are not toxic and support the growth of cells. According to the scratch assay (wound healing test), nanofiber wound dressings contained ATQ, the selected pharmaceutical active ingredient for wound healing with drug repositioning, were 2.75 times more effective in wound healing than nanofibers without ATQ.