Biomedical Engineering Reference
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Figure 45.12. Cumulative release of rhBMP-2 from Ca-P/PHBV scaffolds
with and without surface modification.
after the 1-day release time, while about 1686.71
66.07 ng
rhBMP-2 of cumulative release was found for Ca-P/PHBV scaffolds
withoutsurface modification at the same release time.
The surface-modified Ca-P/PHBV nanocomposite scaffolds with
heparin immobilization exhibited a higher initial burst release
and delivered rhBMP-2 in a more sustained manner than scaf-
foldswithoutsurface modification. Similarsustainedrelease behav-
iors for growth factors such as BMP-2, VEGF, bFGF, and platelet-
derivedgrowthfactor(PDGF)wereobservedforheparin-conjugated
microspheres or scaffold delivery systems. 65 , 69 , 70 After the 28-day
test period, totally about 2860.79 ± 82.54 ng rhBMP-2 was released
fromsurface-modifiedCa-P/PHBVscaffolds,whichwassignificantly
more than the amount released from Ca-P/PHBV scaffolds without
surface modification (2095.90 ± 51.48 ng).
Surface-modified Ca-P/PHBV nanocomposite scaffolds with
immobilized heparin showed better sustained release behavior in
the in vitro release process than scaffolds without surface modifica-
tion, indicating good binding a nity between heparin and rhBMP-2
molecules. Furthermore, much more rhBMP-2 was finally released
from surface modified scaffolds than from scaffolds without surface
modification, with the protection of rhBMP-2 by the immobilized
heparin being one of the contributing factors. Therefore, heparin
immobilization on the surface of Ca-P/PHBV nanocomposite
±
 
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