Development of hydroxyapatite-mediated synthesis of collagen-based copolymers for application as bio scaffolds in bone r
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Development of hydroxyapatite-mediated synthesis of collagen-based copolymers for application as bio scaffolds in bone regeneration Didarul Bhuiyan1, John Middleton1 and Rina Tannenbaum2 1
Department of Biomedical Engineering, University of Alabama at Birmingham, Birmingham, AL 35924, USA. 2 Department of Materials Science and Engineering, Program in Chemical and Molecular Engineering, Stony Brook University, Stony Brook, NY 11794, USA. ABSTRACT Hydroxyapatite (HAP) is a biocompatible bio-ceramic whose structure and composition is similar to bone. However, its lack of strength and toughness have seriously hampered its applications as a bone graft substitute material. Attempts have been made to overcome these mechanical properties deficiencies by combining HAP bioceramic material with absorbable polymers in order to improve its mechanical properties. However, poor interfacial bonding between the HAP and the polymers has limited the benefits of such biocomposite structures. At the other end of the biomaterials spectrum is collagen, which constitutes the most abundant proteins in the body and exhibits properties such as biodegradability, bioadsorbability with low antigenicity, high affinity to water, and the ability to interact with cells through integrin recognition. These favorable properties renders collagen as a natural candidate for the modification and compatibilization of the polymerHAP biocomposite. In this study, we developed a novel approach to the synthesis of a potential bone graft material, where the HAP moiety acts not only as a bioceramic filler, but also constitutes the initiator surface that promotes the in-situ polymerization of the adsorbable polymer of choice. The synthesis of poly(D,L-lactide-co-glycolide) (PLGA) polymer was catalyzed by nanohydroxyapatite (nHAP) particles and upon reaction completion, the biocomposite material was tethered with collagen. The synthesis was monitored by 1H NMR and FTIR spectroscopies and the products after each step were characterized by thermal analysis to probe both thermal stability, morphological integrity and mechanical properties.
INTRODUCTION Bone grafts can serve as scaffolds onto which natural bone can grow and regenerate and hence, can be used in the process of replacing deficient bone in order to repair fractures and defects caused by congenital disorders, traumatic injury, or resection of bone tumors.1,2 Autogenous bone graft sources are widely used because they have a lower frequency of rejection by the immune system. However, in some cases, availability is limited and some complications, such as chronic pain, scarring, bleeding, and infection at the removal site, may occur. Allogeneic bone grafting is another option, but it carries with it increased probability of rejection. Extensive ongoing research is devoted to the development of biocompatible scaffold materials that are made of synthetic or natural biomaterials and that would promote migration, proliferation and differentiation of bone cells for bone regeneration.3-4 At present, there are no syn
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