TY - JOUR
T1 - Novel factor-loaded polyphosphazene matrices
T2 - Potential for driving angiogenesis
AU - Oredein-Mccoy, Olugbemisola
AU - Krogman, Nicholas R.
AU - Weikel, Arlin L.
AU - Hindenlang, Mark D.
AU - Allcock, Harry R.
AU - Laurencin, Cato T.
N1 - Funding Information:
The authors acknowledge funding received from the NIH Grant R01 AR052536 and the University of Virginia Biotechnology Training Program Grant 5P32GM008715-08, as well as use of research facilities at the University of Virginia departments of Orthopaedic Surgery, Biomedical Engineering, Chemical Engineering and the School of Medicine. The authors also recognize the polymer synthesis resources provided by the Pennsylvania State University Department of Chemistry.
PY - 2009/9
Y1 - 2009/9
N2 - Currently employed bone tissue engineered scaffolds often lack the potential for vascularization, which may be enhanced through the incorporation of and regulated release of angiogenic factors. For this reason, the objective here was to fabricate and characterize protein-loaded amino acid ester polyphosphazene (Pphos)-based scaffolds and evaluate the novel sintering method used for protein incorporation, a method which will ultimately allow for the incorporation of proangiogenic agents. To test the hypothesis, Pphos and their composite microspheres with nanocrystalline hydroxyapatite (Pphos-HAp) were fabricated via the emulsion solvent evaporation method. Next, bovine serum albumin (BSA)-containing microsphere matrices were created using a novel solventnon-solvent approach for protein loading. The resulting protein (BSA) loaded circular porous microsphere based scaffolds were characterized for morphology, porosity, protein structure, protein distribution and subsequent protein release pattern. Scanning electron microscopy revealed porous microsphere scaffolds with a smooth surface and sufficient level of sintering, illustrated by fusion of adjacent microspheres. The porosity measured for the poly(ethyl phenylalanato:glycinato)phosphazene (PNPhGly) and poly(ethyl phenylalanato:glycinato)phosphazene-hydroxyapatite (PNPhGly-HAp) scaffolds were 23 ± 0.11 and 18 ± 4.02, respectively, and within the range of trabecular bone. Circular dichroism confirmed an intact secondary protein structure for BSA following the solvent sintering method used for loading and confocal microscopy verified that FITC-BSA was successfully entrapped both between adjacent microspheres and within the surface of the microspheres while sintering. For both Pphos and their composite microsphere scaffolds, BSA was released at a steady rate over a 21 day time period, following a zero order release profile. HAp particles in the composite scaffolds served to improve the release profile pattern, underscoring the potential of HAp for growth factor delivery. Moreover, the results of this work suggest that the solventnon-solvent technique for protein loading is an optimal one that will allow for future development of angiogenic factor-loaded Pphos matrices with the capacity to invoke neovascularization.
AB - Currently employed bone tissue engineered scaffolds often lack the potential for vascularization, which may be enhanced through the incorporation of and regulated release of angiogenic factors. For this reason, the objective here was to fabricate and characterize protein-loaded amino acid ester polyphosphazene (Pphos)-based scaffolds and evaluate the novel sintering method used for protein incorporation, a method which will ultimately allow for the incorporation of proangiogenic agents. To test the hypothesis, Pphos and their composite microspheres with nanocrystalline hydroxyapatite (Pphos-HAp) were fabricated via the emulsion solvent evaporation method. Next, bovine serum albumin (BSA)-containing microsphere matrices were created using a novel solventnon-solvent approach for protein loading. The resulting protein (BSA) loaded circular porous microsphere based scaffolds were characterized for morphology, porosity, protein structure, protein distribution and subsequent protein release pattern. Scanning electron microscopy revealed porous microsphere scaffolds with a smooth surface and sufficient level of sintering, illustrated by fusion of adjacent microspheres. The porosity measured for the poly(ethyl phenylalanato:glycinato)phosphazene (PNPhGly) and poly(ethyl phenylalanato:glycinato)phosphazene-hydroxyapatite (PNPhGly-HAp) scaffolds were 23 ± 0.11 and 18 ± 4.02, respectively, and within the range of trabecular bone. Circular dichroism confirmed an intact secondary protein structure for BSA following the solvent sintering method used for loading and confocal microscopy verified that FITC-BSA was successfully entrapped both between adjacent microspheres and within the surface of the microspheres while sintering. For both Pphos and their composite microsphere scaffolds, BSA was released at a steady rate over a 21 day time period, following a zero order release profile. HAp particles in the composite scaffolds served to improve the release profile pattern, underscoring the potential of HAp for growth factor delivery. Moreover, the results of this work suggest that the solventnon-solvent technique for protein loading is an optimal one that will allow for future development of angiogenic factor-loaded Pphos matrices with the capacity to invoke neovascularization.
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U2 - 10.1080/02652040802500473
DO - 10.1080/02652040802500473
M3 - Article
C2 - 18972247
AN - SCOPUS:70849103437
SN - 0265-2048
VL - 26
SP - 544
EP - 555
JO - Journal of Microencapsulation
JF - Journal of Microencapsulation
IS - 6
ER -