title: Development and characterization of biodegradable nanocomposite injectables for orthopaedic applications based on polyphosphazenes.
abstract: Self-setting hydroxyapatite-biodegradable injectable composites are excellent candidates for applications in orthopaedics. We have previously demonstrated the feasibility of development of self-setting calcium-deficient nanocrystalline hydroxyapatite-polymer composites using different calcium phosphate precursors and biodegradable polyphosphazenes. This study aimed to evaluate these novel injectable composites as suitable materials for orthopaedic applications through evaluating their biomechanical properties, osteoblast cellular attachment and gene expression over time. Our studies demonstrated that the morphology of the composite groups (PNEA-CDHA, PNEA-CDSHA, PNEA(50)mPh(50)-CDHA, PNEA(50)mPh(50)-CDSHA, PNEA(50)PhPh(50)-CDHA, and PNEA(50)PhPh(50)-CDSHA) formed was similar and found to have micro- and nanoporous structures resembling trabecular bone. The osteoblast phenotypic marker of bone, alkaline phosphatase, was expressed by the cells on the surface of the composites throughout the study and was comparable to tissue-culture polystyrene (control). Furthermore, the cells seeded on the composites expressed the characteristic osteoblastic genes, such as type-I collagen, alkaline phosphatase, osteocalcin, osteopontin and bone sialoprotein, indicating osteoblast differentiation, maturation and mineralization. Within our injectable composite groups, significant gene expression levels were displayed (P < 0.05). These novel injectable biodegradable polyphosphazenes-calcium-deficient hydroxyapatites materials are promising candidates for orthopaedic applications.
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: 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: D016475:3T3 Cells; D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry* / Q000378:metabolism; D015870:Gene Expression; D007267:Injections; D008422:Materials Testing; D051379:Mice; D015394:Molecular Structure; D053761:Nanocomposites / Q000737:chemistry*; D009943:Organophosphorus Compounds / Q000737:chemistry* / Q000378:metabolism; D019637:Orthopedic Procedures; D011108:Polymers / Q000737:chemistry* / Q000378:metabolism; D017550:Spectroscopy, Fourier Transform Infrared; D014961:X-Ray Diffraction
chemical_list: D001672:Biocompatible Materials; D009943:Organophosphorus Compounds; D011108:Polymers; C108974:poly(phosphazene)