Polyphosphazene/nano-hydroxyapatite composite microsphere scaffolds for bone tissue engineering.
The nontoxic, neutral degradation products of amino acid ester polyphosphazenes make them ideal candidates for in vivo orthopedic applications. The quest for new osteocompatible materials for load bearing tissue engineering applications has led us to investigate mechanically competent amino acid ester substituted polyphosphazenes. In this study, we have synthesized three biodegradable polyphosphazenes substituted with side groups, namely, leucine, valine, and phenylalanine ethyl esters. Of these polymers, the phenylalanine ethyl ester substituted polyphosphazene showed the highest glass transition temperature (41.6 degrees C) and, hence, was chosen as a candidate material for forming composite microspheres with 100 nm sized hydroxyapatite (nHAp). The fabricated composite microspheres were sintered into a three-dimensional (3-D) porous scaffold by adopting a dynamic solvent sintering approach. The composite microsphere scaffolds showed compressive moduli of 46-81 MPa with mean pore diameters in the range of 86-145 microm. The 3-D polyphosphazene-nHAp composite microsphere scaffolds showed good osteoblast cell adhesion, proliferation, and alkaline phosphatase expression and are potential suitors for bone tissue engineering applications.
Department of Orthopaedic Surgery, University of Virginia, Charlottesville, Virginia 22908, USA.
Syam P
SP
Nukavarapu
Sangamesh G
SG
Kumbar
Justin L
JL
Brown
Nicholas R
NR
Krogman
Arlin L
AL
Weikel
Mark D
MD
Hindenlang
Lakshmi S
LS
Nair
Harry R
HR
Allcock
Cato T
CT
Laurencin
D000469:Alkaline Phosphatase / Q000096:biosynthesis; D001672:Biocompatible Materials / Q000737:chemistry; D018786:Bone Substitutes / Q000737:chemistry; D001842:Bone and Bones / Q000166:cytology*; D002448:Cell Adhesion; D049109:Cell Proliferation; D017886:Durapatite / Q000737:chemistry*; D006801:Humans; D008863:Microspheres; D009943:Organophosphorus Compounds / Q000737:chemistry*; D010006:Osteoblasts / Q000166:cytology*; D011108:Polymers / Q000737:chemistry*; D016062:Porosity; D023822:Tissue Engineering / Q000379:methods*
D001672:Biocompatible Materials; D018786:Bone Substitutes; D009943:Organophosphorus Compounds; D011108:Polymers; C108974:poly(phosphazene); D017886:Durapatite; D000469:Alkaline Phosphatase