TY - JOUR
T1 - The role of hydroxyapatite in citric acid-based nanocomposites
T2 - Surface characteristics, degradation, and osteogenicity in vitro
AU - Chung, Eun Ji
AU - Sugimoto, Matthew J.
AU - Ameer, Guillermo A.
N1 - Funding Information:
This work was supported by a NSF Career Award granted to Dr. Guillermo Ameer. Electron microscopy was performed in the Electron Probe Instrumentation Center facility of the NUANCE Center at Northwestern University, and is supported by the NSF-NSEC , the NSF-MRSEC , the Keck Foundation , the State of Illinois , and Northwestern University . The authors thank Andrew McGrain for assistance with the degradation studies and Aaron Lau for assistance with the contact angle measurements.
PY - 2011/11
Y1 - 2011/11
N2 - The incorporation of nanoscale hydroxyapatite (HA) into biodegradable polymers can potentially mimic the native structure of bone and influence the mechanical properties and the extent of bioactivity. In this study nanocomposites of poly(1,8-octanediol-co-citrate) (POC) containing 40, 50, and 60 wt.% HA (POC-HA) were fabricated and characterized. Nanocomposite hydrophilicity and the degradation properties in vitro were evaluated via contact angle measurements, scanning electron microscopy (SEM), and mass loss measurements. Human mesenchymal stem cells (hMSC) were cultured on POC-HA nanocomposites in both growth and osteogenic media. Cell proliferation, alkaline phosphatase activity, and osteocalcin were measured. The equilibrium water in air contact angles confirmed all of the nanocomposites to be hydrophilic (23.4 ± 8.1°, 27 ± 9.1°, and 27.7 ± 3.5° for 40, 50, and 60 wt.% HA, respectively). Over a period of 26 weeks the degradation rate increased with decreasing HA content and pore formation was evident for POC-HA containing 40 wt.% HA, whereas POC with 50 and 60 wt.% HA lacked pores (mass loss at 26 weeks for 40, 50, and 60 wt.% HA, 27.4 ± 1.6%, 17.7 ± 1.6%, and 6.3 ± 2.6%, respectively). hMSC adhered and proliferated well on all composites, confirming biocompatibility for at least 21 days. An increase in adhesion and proliferation was found with increasing HA nanoparticle content (ng DNA at day 21 for 40, 50, and 60 wt.% HA, 130.4 ± 49.4, 184.4 ± 86.4, 314.1 ± 92.3). Alkaline phosphatase activity and osteocalcin concentration correlated with HA content (alkaline phosphate activity in expansion medium and osteogenic medium for 40, 50, and 60 wt.% HA, 256.1 ± 71.8%, 304.0 ± 128.7%, and 500.2 ± 89.9%, and 358.4 ± 124.1%, 653.7 ± 216.5%, and 814.4 ± 68.8%, respectively; osteocalcin concentration in expansion medium and osteogenic medium for 40, 50, and 60 wt.% HA, 236.9 ± 7.8%, 253.0 ± 7.5%, and 285.2 ± 11.4%, and 265.8 ± 15.0%, 288.3 ± 17.9%, and 717.3 ± 38.7%, respectively). This study provides insight into how the HA nanoparticle content can modulate the cell compatibility and physical properties of POC-HA nanocomposites.
AB - The incorporation of nanoscale hydroxyapatite (HA) into biodegradable polymers can potentially mimic the native structure of bone and influence the mechanical properties and the extent of bioactivity. In this study nanocomposites of poly(1,8-octanediol-co-citrate) (POC) containing 40, 50, and 60 wt.% HA (POC-HA) were fabricated and characterized. Nanocomposite hydrophilicity and the degradation properties in vitro were evaluated via contact angle measurements, scanning electron microscopy (SEM), and mass loss measurements. Human mesenchymal stem cells (hMSC) were cultured on POC-HA nanocomposites in both growth and osteogenic media. Cell proliferation, alkaline phosphatase activity, and osteocalcin were measured. The equilibrium water in air contact angles confirmed all of the nanocomposites to be hydrophilic (23.4 ± 8.1°, 27 ± 9.1°, and 27.7 ± 3.5° for 40, 50, and 60 wt.% HA, respectively). Over a period of 26 weeks the degradation rate increased with decreasing HA content and pore formation was evident for POC-HA containing 40 wt.% HA, whereas POC with 50 and 60 wt.% HA lacked pores (mass loss at 26 weeks for 40, 50, and 60 wt.% HA, 27.4 ± 1.6%, 17.7 ± 1.6%, and 6.3 ± 2.6%, respectively). hMSC adhered and proliferated well on all composites, confirming biocompatibility for at least 21 days. An increase in adhesion and proliferation was found with increasing HA nanoparticle content (ng DNA at day 21 for 40, 50, and 60 wt.% HA, 130.4 ± 49.4, 184.4 ± 86.4, 314.1 ± 92.3). Alkaline phosphatase activity and osteocalcin concentration correlated with HA content (alkaline phosphate activity in expansion medium and osteogenic medium for 40, 50, and 60 wt.% HA, 256.1 ± 71.8%, 304.0 ± 128.7%, and 500.2 ± 89.9%, and 358.4 ± 124.1%, 653.7 ± 216.5%, and 814.4 ± 68.8%, respectively; osteocalcin concentration in expansion medium and osteogenic medium for 40, 50, and 60 wt.% HA, 236.9 ± 7.8%, 253.0 ± 7.5%, and 285.2 ± 11.4%, and 265.8 ± 15.0%, 288.3 ± 17.9%, and 717.3 ± 38.7%, respectively). This study provides insight into how the HA nanoparticle content can modulate the cell compatibility and physical properties of POC-HA nanocomposites.
KW - Bone tissue engineering
KW - Citric acid
KW - Hydroxyapatite
KW - Mesenchymal stem cell
KW - Osteogenicity
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U2 - 10.1016/j.actbio.2011.07.001
DO - 10.1016/j.actbio.2011.07.001
M3 - Article
C2 - 21784176
AN - SCOPUS:80053566497
SN - 1742-7061
VL - 7
SP - 4057
EP - 4063
JO - Acta Biomaterialia
JF - Acta Biomaterialia
IS - 11
ER -