Development of polyvinyl alcohol based hydrogels with antibacterial properties and can be self-heali̇ng used as wound dressings

Statistically speaking, burn injuries, which are likely to happen to hundreds of people every day, can negatively affect daily life. Burn wounds can be caused by boiled water or liquids, fire, frying oil, etc., which we use for the continuation of vital functions, as well as by less common factors such as a cold environment that the human body cannot withstand or radiation, electrical contact with high voltage. In such cases, the healing mechanism is activated in the deformed tissue area and damage repair begins. This mechanism is a very complex process involving intertwined hemostasis, inflammatory, proliferation and remodeling phases, and at the end of the process, the wound heals. The hemostasis phase creates a buffer in the injured area by forming clots with the help of platelets to stop the possibility of bleeding, followed by an inflammatory phase, which aims to protect the wound site by destroying harmful factors and microorganisms outside through phagocytosis by neutrophils and macrophages. This phase is followed by the proliferation phase, in which the cells proliferate and aim to repair the damaged tissue by restoring the skin functions to its former form, and then the process is completed with the maturation and remodeling phase, which is the last stage of healing, in which the damaged tissue is repaired by increasing the tensile strength of the damaged tissue and reshaping it. In some cases, the deformed tissue cannot regenerate itself and needs to be treated with medical interventions. Untreated tissues may be lost over time and the patient's life may be negatively affected. In order to avoid such situations, the degree of burn should be determined and the appropriate treatments should be applied to the wound location quickly and effectively. In order to determine the degree of burn, it is important to know the exact location on the deformed skin. The skin is basically a structure with 3 different layers called epidermis, dermis and hypodermis, and it is an organ with the title of the largest surface area by covering the whole body. Damages in the epidermis layer are called first-degree burns, and redness can be seen on the skin. Damage reaching the dermis layer is examined in two categories. While superficial partial burns are observed on the surface of the dermis together with the epidermis, dermal partial burns also damage the lower parts of the dermis. In second degree burns, there are symptoms such as redness and blistering, and severe pain is felt, which means that the nerve endings are not damaged. Third-degree burns that reach the hypodermis layer, and burns that cause extensive damage to not only the skin but also the muscle and bone, are defined as fourth-degree burns. The absence of pain sensation means that the nerves are damaged. After these determinations are made, it is aimed to treat the wound area by choosing the appropriate methods. One of these methods is hydrogel dressings, which aim to reduce the risk of infection by separating the wound area from the external environment.Hydrogel semi-wound dressings are one of the types of wound dressings created by combining various natural or synthetic polymers and additives. The main purpose is to provide protection by keeping the wound moist, allowing the entry and exit of the oxygen it needs and preventing harmful microorganisms from positioning around the wound. Hydrogel dressings are one of the types of wound dressings synthesized by combining various natural or synthetic polymers and additives. The main purpose is to provide protection by keeping the wound moist, providing the oxygen it needs in and out, and preventing harmful microorganisms from settling around the wound. Its easily removable structure offers a treatment process without damaging the wound. These wound dressings, which allow gas exchange thanks to the pores in their structure, are promising. In this thesis, first of all, Polyvinyl alcohol (PVA) and Polyethylene glycol (PEG) added hydrogel dressings were synthesized. For this, PVA aqueous solution was prepared with stirring intensity in the presence of high temperature and magnetic field, and PEG polymer was added into it and dissolved. It is preferred to add tannic acid (TA) as a crosslinker. Eucalyptus and clove essential oils, which are preferred as additives, aimed to increase the antibacterial properties of the hydrogel. The second dressing study was synthesized by preferring PVA and Polyvinyl prolidine (PVP) polymers. It is preferred to add TA as a crosslinker. In this dressing, the drug release profile with the drug additive was examined, and the antibacterial properties of the medicated and non-medicated hydrogel dressings with the same content were compared, and as a result, it was observed that the antibacterial effects of the drug added hydrogel samples were stronger. Polyethyleneimine (PEI) polymer doped hydrogel was synthesized together with PVA as the third type of wound dressing. As a result of the observations, it was determined that PEI polymer dissolves faster in distilled water compared to other polymers. As the amount of TA preferred as crosslinker increased in the samples, it was observed that the colors became darker. In addition, it was determined that the mechanical strength of the samples, which were subjected to the tensile test, decreased inversely depending on the increase in the amount of TA. In PVA/PVP hydrogel samples, it was determined that the gentamicin added samples had a very effective antibacterial field against E.coli and S. aureus bacteria. It has also been observed that controlled drug release occurs from hydrogel samples with good hydrophilic properties. Hydrogel samples, which have been found to be mechanically durable, are also thought to be developed for use as wound dressings. FTIR analysis was applied to understand the structural bonding of the developed hydrogel samples. In order to test their antibacterial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), they were incubated in petri dishes containing bacterial culture medium at 37°C for 24 hours. In order to investigate the water absorption, moisture retention capacity and hydrophilic properties of the prepared hydrogels, characterizations such as swelling tests, moisture retention tests and contact angle measurements were performed. In addition, scratch tests were performed to determine the self-healing and non-freezing abilities of the hydrogels and the results were observed under an optical microscope. SEM analysis was used to investigate the pore structures and UV-spectrophotometer was used to understand the gentamicin release. Tensile tests were performed on the samples for mechanical strength and the characterization tests were analyzed. When the test results were examined, it was determined that the PEG1 and PEG/OCALIPTUS hydrogel samples for the first study were samples with high hydrophilic properties, high swelling capacity, with better antibacterial effect against S. aureus bacteria. It was also observed that the hydrogel samples with the highest mechanical strength were the samples with PEG additives. In PVA/PVP hydrogel samples, it was determined that the gentamicin added samples had a very effective antibacterial field against E.coli and S. aureus bacteria. It has also been observed that controlled drug release occurs from hydrogel samples with good hydrophilic properties. Hydrogel samples, which have been found to be mechanically durable, are also thought to be developed for use as wound dressings. It has been determined that PVA/PEI hydrogel samples have high antibacterial properties in drug-free samples, and it has been determined that drug-added samples have a very wide range of action against E.coli and S. aureus bacteria. It has also been observed that it has good hydrophilic properties. In addition, in this hydrogel study, it showed non-freezing property in one of the lyophilized and frozen samples. It has also been found that there are wound dressing samples with self-healing properties without any external influence or stimulus. As a result, it was determined that the samples synthesized for the development of good and useful wound dressings with higher antibacterial properties were successfully developed and promising to be used.