title: Mechanical properties and osteocompatibility of novel biodegradable alanine based polyphosphazenes: Side group effects.
abstract: The versatility of polymers for tissue regeneration lies in the feasibility to modulate the physical and biological properties by varying the side groups grafted to the polymers. Biodegradable polyphosphazenes are high-molecular-weight polymers with alternating nitrogen and phosphorus atoms in the backbone. This study is the first of its kind to systematically investigate the effect of side group structure on the compressive strength of novel biodegradable polyphosphazene based polymers as potential materials for tissue regeneration. The alanine polyphosphazene based polymers, poly(bis(ethyl alanato) phosphazene) (PNEA), poly((50% ethyl alanato) (50% methyl phenoxy) phosphazene) (PNEA(50)mPh(50)), poly((50% ethyl alanato) (50% phenyl phenoxy) phosphazene) (PNEA(50)PhPh(50)) were investigated to demonstrate their mechanical properties and osteocompatibility. Results of mechanical testing studies demonstrated that the nature and the ratio of the pendent groups attached to the polymer backbone play a significant role in determining the mechanical properties of the resulting polymer. The compressive strength of PNEA(50)PhPh(50) was significantly higher than poly(lactide-co-glycolide) (85:15 PLAGA) (p<0.05). Additional studies evaluated the cellular response and gene expression of primary rat osteoblast cells on PNEA, PNEA(50)mPh(50) and PNEA(50)PhPh(50) films as candidates for bone tissue engineering applications. Results of the in vitro osteocompatibility evaluation demonstrated that cells adhere, proliferate, and maintain their phenotype when seeded directly on the surface of PNEA, PNEA(50)mPh(50), and PNEA(50)PhPh(50). Moreover, cells on the surface of the polymers expressed type I collagen, alkaline phosphatase, osteocalcin, osteopontin, and bone sialoprotein, which are characteristic genes for osteoblast maturation, differentiation, and mineralization.
authors.affiliation: Center for Nanotechnology & Advanced Biomaterials, SASTRA University, Thanjavur, India.
authors.forename: Swaminathan
authors.initials: S
authors.lastname: Sethuraman
authors.forename: Lakshmi S
authors.initials: LS
authors.lastname: Nair
authors.forename: Saadiq
authors.initials: S
authors.lastname: El-Amin
authors.forename: My-Tien
authors.initials: MT
authors.lastname: Nguyen
authors.forename: Anurima
authors.initials: A
authors.lastname: Singh
authors.forename: Nick
authors.initials: N
authors.lastname: Krogman
authors.forename: Yaser E
authors.initials: YE
authors.lastname: Greish
authors.forename: Harry R
authors.initials: HR
authors.lastname: Allcock
authors.forename: Paul W
authors.initials: PW
authors.lastname: Brown
authors.forename: Cato T
authors.initials: CT
authors.lastname: Laurencin
mesh_terms: D020341:Absorbable Implants; D000409:Alanine / Q000737:chemistry*; D000818:Animals; D000831:Animals, Newborn; D001672:Biocompatible Materials / Q000737:chemistry*; D002478:Cells, Cultured; D019245:Compressive Strength; D055119:Elastic Modulus; D008422:Materials Testing; D009943:Organophosphorus Compounds / Q000737:chemistry*; D010006:Osteoblasts / Q000166:cytology* / Q000502:physiology*; D011108:Polymers / Q000737:chemistry*; D051381:Rats; D023822:Tissue Engineering / Q000379:methods*
chemical_list: D001672:Biocompatible Materials; D009943:Organophosphorus Compounds; D011108:Polymers; C108974:poly(phosphazene); D000409:Alanine