Mechanical properties and osteocompatibility of novel biodegradable alanine based polyphosphazenes: Side group effects

Swaminathan Sethuraman, Lakshmi S. Nair, Saadiq El-Amin, My Tien Nguyen, Anurima Singh, Nick Krogman, Yaser E. Greish, Harry R. Allcock, Paul W. Brown, Cato T. Laurencin

Research output: Contribution to journalArticlepeer-review

98 Citations (Scopus)


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 50mPh50), poly((50% ethyl alanato) (50% phenyl phenoxy) phosphazene) (PNEA50PhPh50) 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 PNEA50PhPh50 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, PNEA50mPh50 and PNEA50PhPh 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, PNEA50mPh50, and PNEA 50PhPh50. 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.

Original languageEnglish
Pages (from-to)1931-1937
Number of pages7
JournalActa Biomaterialia
Issue number6
Publication statusPublished - Jun 2010
Externally publishedYes


  • Biodegradable polyphosphazenes
  • Gene expression
  • Mechanical properties
  • Osteocompatibility

ASJC Scopus subject areas

  • Biotechnology
  • Biomaterials
  • Biochemistry
  • Biomedical Engineering
  • Molecular Biology


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