Development and characterization of surgical locally oxidised regenerated cellulose hemostats

Abstract

Blood is not only a special fluid that transports gases and nutrients but is also responsible for immune control and hemostatic response. Generally, mild bleeding can be stopped by congenital clotting. However, excessive blood loss can cause morbidity (illness) and even mortality (death). Therefore, when haemorrhage occurs, there is a critical time window in which effective treatment must be given to save lives. Uncontrolled excessive bleeding is a life-threatening emergency scenario that significantly impairs patients' survival within the first 48 hours and causes millions of deaths worldwide each year. Large-scale bleeding in battlefields, traffic accidents and during surgical operations can cause high blood loss, which adversely affects physiological processes in the body. With excessive blood loss, there is a decrease in the amount of blood carrying nutrients and oxygen necessary for the metabolic activities of cells in tissues and organs, and metabolic wastes produced by cells begin to accumulate in the intercellular space. If bleeding cannot be prevented for a long time, the blood necessary for the heart to function itself cannot be supplied and bleeding may result in death. In addition, uncontrolled bleeding in patients with coagulopathy is associated with massive bleeding in emergency situations. Excessive bleeding may disrupt the hemodynamics of patients and may require additional blood transfusion. Prolonged treatment may cost life. Therefore, it is critical to stop bleeding in emergencies, especially in cases of organ trauma. In addition, uncontrolled bleeding is not only a life-threatening situation for patients, but also a great financial burden for health services. In this context, hemostatic agents are vital for the rapid prevention of bleeding. Hemostatic materials are generally produced from natural materials such as chitosan, cellulose, starch. Existing hemostatic agents have disadvantages such as acidity, surrounding cell damage, acute/chronic inflammation, thrombogenic complications, non-biodegradability, limited application methods, short shelf life and high cost and impose a serious cost on health expenditures. In this respect, it is important to develop materials with low cost and hemostatic properties to stop bleeding at the time of injury. The main aim of this project is to produce an absorbable hemostatic agent from sustainable natural origin cellulosic fibres obtained from cellulose wastes and to quickly stop and prevent bleeding in tissues. These hemostatic agents produced from polysaccharides or other biopolymers are expected to have properties such as biodegradability, biocompatibility and non-exothermic reaction, and these issues have become the focus in the development of new generation hemostatic materials. In this study, it is planned to produce a non-woven, absorbable hemostatic material that accelerates plasmination for the first time by using TENCEL fibre, which is produced from polysaccharide type materials, sustainable regenerated cellulose obtained from cellulose wastes, provides more hygienic properties by creating an environment less favourable to bacterial growth and has the potential to reduce the risk of irritation and negative effects on the body by providing a smoother surface and softness. It is aimed to use TENCEL fibre as the main material in the production of cellulosic hemostatic agent and to develop surgical local hemostat by oxidation of the felt to be obtained. Thus, it is aimed to evaluate innovative natural origin sustainable fibres in the production of medical textile products and to transform them into value added products. As a start, Tencel fibre supplied by Göl Iplik, one of our project sponsors, was purchased in fibre form and delivered to Karınca Filter facilities, also one of our project supporters. Our Tencel fibre was taken to the Dilo machine in the facility where fiber preparation, carding, cross-laying, lap drawing and needling processes were carried out respectively. Firstly, 16 plies were tried in cross-laying, but since the thickness of the product was too high, the number of plies was also tried as 12 and 8. As the tencel fibre gains volume after passing through the carding machine, the product was also evaluated by needling at the same time. Two different drums of the needling section were evaluated and our 8-layer product was needled as 49K and 16K respectively and formed as 2 different samples. Finally, 4 types of samples were chosen for the subsequent studies: 12 layers un-needled, 8 layers un-needled, 8 layers 49K needled and 8 layers 16K needled. Afterwards, by comparing the samples chosen with their equivalents in the market, it was decided that the 8 ply 16K needled sample was the most suitable one with the properties required. 8 ply 16K needled sample, which is accepted as the optimum sample, has been oxidised. The oxidation process was carried out in a closed system in a stainless metal boiler in Yucel Medical facility. In the closed boiler, 250 grams of nitrogen dioxide (NOx) gas was given for 3 kg of nonwoven product and the trapped product was kept at a temperature of 20-25 C for 24 hours. Afterwards, it is removed from the boiler and placed in a container containing approximately 10 litres of ethyl alcohol by an operator using a mask as soon as it is removed. It is kept in the container full of ethyl alcohol for 30 minutes. Afterwards, the pH value is measured, if it is not suitable, ethyl alcohol washing is continued again. After washing 4 times with ethyl alcohol, the desired pH value is reached. The pH value is targeted between 2,8 and 4. The reason for this is the antibacterial effect of the product between these standards. Then it is left to dry in a clean environment in a laminal cabinet. It is dried and kept for about 12 hours. After nonwoven products of suitable texture formed by using Tencel fibre were oxidised under suitable ambient conditions, carboxyl ratios, optimum pH and solubility were achieved. Moreover, loss on drying test, nitrogen content, formaldeyhyde test is performed, and the results are in the standards according to USP28 (United States Pharmacopeia) Pharmacopoeia standard. Carboxyl test was applied on the dried product to determine carboxyl ratios. The purpose of this is to see whether the product complies with the USP28 (United States Pharmacopeia) Pharmacopoeia standard. The appropriate carboxyl amount indicates that the product can be absorbed in the body. Since pH is a crucial factor in determining a material's biological compatibility and functioning, pH test was applied. The degree of oxidation and the presence of acidic groups in oxidized regenerated cellulose might influence how the material dissolves or is suspended in water. Solubility testing of oxidised regenerated cellulose (ORC) is necessary to evaluate its performance in medical applications. Drying loss test was applied to the newly produced product and the product on the market. Specific weights of materials taken separately from both samples will be dried at specified temperatures for 2 hours. After drying, the weight of the materials will be measured again. Nitrogen content analysis on oxidised regenerated cellulose is a fundamental analytical technique that supports quality assurance, regulatory compliance and research efforts related to this important biomaterial. That is why we did the nitrogen content test. Formaldehyde testing on oxidised regenerated cellulose is essential to verify compliance with safety regulations, ensure patient safety and maintain the quality and integrity of the material for medical applications. For this reason, we performed the formaldehyde test. In the method used in the production of the hemostatic agent developed within the scope of the project, the information obtained from the literature was combined with the research experience of the project team and the process parameters were determined and optimised. In addition, tests of the produced hemostatic material and a commercial material were carried out in accredited laboratories and the potential for commercialisation was evaluated by comparing their performances.