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Double network hydrogels for cartilage repair and their nanocomposite structure

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Title: Double network hydrogels for cartilage repair and their nanocomposite structure
Authors: Mohammed, Ali
Item Type: Thesis or dissertation
Abstract: Strong focus has been directed at cartilage tissue engineered biomaterials in the last decade. Cartilage defects affect a large global population with current treatments lacking the ability to provide a route to healthy hyaline cartilage, or a road to full recovery and normal mobility. Synthetic materials such as scaffolds and hydrogels are making breakthroughs as advanced biomaterials and have gathered momentum in providing a solution. In particular, double network hydrogels (DNHG) have become a standard for developing materials that replicate the properties of cartilage. DNHG consist of two contrasting polymers that are synthesised sequentially by free radical polymerization (FRP). This thesis focuses on DNHG and their ability to be cross linked using silica nanoparticles (SNP) and nanoceria (NC) for the purpose of cartilage repair. These two nanostructures were chosen to provide the DNHG with tailorable mechanical properties. Polyacrylic acid (PAAc) and a poly2-acrylamido-2-methylpropane sulfonic acid (PAMPS) were chosen as the basis for the first networks, while polyacrylamide (PAAm) was chosen as the second network for both. The chemical, morphological and mechanical properties of these materials were investigated using several characterization techniques. Further, investigating the kinetics of FRP in an open-vessel environment revealed oxygen species impact conversion and reaction rates. The impact of GOx on cytotoxicity levels was also conducted on the separate polymers. The addition of glucose oxidase (GOx) as a degassing agent enhanced reaction kinetics, leading to faster and more efficient polymerizations that achieved 100 % polymer conversion. This allowed for optimization of the synthesis route, as well as reducing toxic monomers left in the material. The combination of NC and GOx proved to enhance the polymerization by utilising reaction by-products to create a cyclic reaction route. Finally, polymers were grafted on the surface of the nanostructures of both networks to form new DNHGs.
Content Version: Open Access
Issue Date: Oct-2017
Date Awarded: Mar-2018
URI: http://hdl.handle.net/10044/1/78571
DOI: https://doi.org/10.25560/78571
Copyright Statement: Creative Commons Attribution Non-Commercial No Derivatives licence.
Supervisor: Jones, Julian
Georgiou, Theoni
Department: Materials
Publisher: Imperial College London
Qualification Level: Doctoral
Qualification Name: Doctor of Philosophy (PhD)
Appears in Collections:Materials PhD theses