Cellulose-based hydrogels and aerogels for hemostatic applications
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Hemostasis is an important issue in-clinic treatments for acute wounds. Existing hemostatic materials may not fully meet the demands in emergency situations in terms of hospitals and battlefields which calls for the development of cost-effective hemostatic materials for clinical applications. Cellulose as a natural polymer is abundant in nature and has been widely used in different applications, like food, cosmetics, and hemostatic applications. Cellulose-based materials can absorb water from blood upon contact with wounds, which helps to stop bleeding. In this work, cellulose-based aerogels and hydrogels were prepared and their potential applications as hemostatic materials were explored. Aerogels with ultra-high porosity and large surface area can absorb water from blood and form barriers in the trauma site to stop bleeding. In this thesis, an aerogel with lightweight, injectability, antibacterial ability, water-induced shape memory behavior, and excellent compressibility was developed from carboxymethylated nanocellulose fibers (NCFs), alginate and zinc chloride. The obtained NCFs-alginate aerogels have dual networks which are the physical network of NCFs formed by freeze-drying and physical crosslinking between alginate and zinc ions. Here, zinc chloride endowed the aerogels with the antibacterial ability to prevent infection and reduce the probability of complications due to microorganisms. The NCFs-alginate aerogels with high water absorption can absorb water when contacting blood to stop bleeding. Meanwhile, in the presence of NCFs and alginate, the aerogels can promote wound healing quickly. Besides, injectability and rapid water-induced shape recovery ability (4s) allowed the NCFs-alginate aerogels to be used for penetrating wounds. Carboxymethylated cellulose (CMC) is an important derivation of cellulose and has been widely used in biomedical applications. A facile and environmentally friendly method for preparing self-healing hydrogels using CMC, polyvinyl alcohol (PVA), and borax has been developed. The CMC was grafted with double bonds via triethylamine and methacrylic anhydride (MA). Herein, the hydrogel contains double networks: the chemically crosslinked network formed by methacrylate carboxymethylated cellulose (MACMC) and the physical crosslinking between PVA and borax. The MACMC-PVA hydrogel has rapid self-healing efficiency (8s) due to the presence of reversible hydrogen bonds, including hydrogen bonds between CMC and PVA and dynamic complexation of diol-borax between PVA and borax. Additionally, the MACMC-PVA hydrogel with good tissue-adhesive properties and remarkable stretchability can closely adhere to wound sites of different shapes, including penetrating wounds. The hydrophilicity and higher water absorption rate allow the hydrogel to absorb water from the blood to block bleeding and to provide a moisture environment that promotes wound healing. Based on the above studies, cellulose-based aerogels and hydrogels with high water absorption and outstanding properties can provide an optimum environment to stop bleeding, avoid infection and accelerate wound healing. Therefore, the developed cellulose-based materials have great potential in hemostatic applications.