Chitosan-alginate Hybrid Scaffolds for in Vitro Bone Tissue Regeneration
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Chitosan-alginate hybrid scaffolds for in vitro bone tissue regeneration Zhensheng Li a , Hassna R. Ramay a, Kip D. Hauch b, Miqin Zhang a a Department of Materials Science & Engineering, University of Washington, Seattle, 302L Roberts Hall, WA 98195-2120, USA b Department of Bioengineering, University of Washington, Seattle, WA 98195, USA Abstract This paper reports the development of a biodegradable porous scaffold made from naturally derived chitosan and alginate polymers for bone tissue engineering. The scaffold has a 3-D interconnected porous structure and was fabricated through thermally induced phase separation. The mechanical test showed that the scaffold has compressive strength of 0.46 ± 0.02 MPa — about 4 times that of the pure chitosan scaffold. The cellmaterial interaction study indicated that osteoblast cells seeded on the chitosan-alginate scaffold attach and proliferate well. The mineral deposition occurred after 3 days of culture and formed large chunks after 7 days. The chitosan-alginate scaffold was also found to have desirable swelling property and was structurally stable in solutions of different pH. The chitosan-alginate scaffold can be prepared from solutions of neutral pH allowing growth factors to be incorporated homogeneously into the scaffold for sustained release. This research demonstrated a technique by which a polymer-based biodegradable scaffold can be made to have high porosity up to 92% and excellent mechanical and biological properties. Key words: chitosan, alginate, scaffold, bone tissue, biodegradable Introduction Tissue engineering, as an emerging field, offers excellent opportunities for bone reconstruction. A biodegradable scaffold in tissue engineering serves as a temporary skeleton inserted into the sites of defective or lost bone to support and stimulate bone tissue regeneration while it gradually degrades and is replaced by new bone. Clinically, bioactive ceramics and polymers have been most widely investigated. Bioactive ceramics have chemical composition resembling that of natural bone, allows osteogenesis to occur, and can provide a bony contact or bonds with host bone.[1, 2] In spite of their favorable biological properties/the brittleness, low toughness, and low biodegradation rates of ceramics have severely limited their clinical use. Biopolymers, on the other hand, have some distinct advantages over ceramic materials. Their biodegradation rates and mechanical properties can be tailored to certain extent for specific applications. They are particularly amenable for implantation and can be easily manufactured into desired shapes.[3] Chitosan is biologically renewable, biodegradable, biocompatible, non-antigenic, non-toxic, and bio-functional. [4] Unlike synthetic polymers having hydrophobic surfaces, chitosan has a hydrophilic surface promoting cell adhesion, proliferation and differentiation, and evokes a minimal foreign body reaction on implantation.[5, 6] It has been used in wound dressing, wound healing, drug delivery and various tissue engineering applica
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