aSchool of Materials Science and Engineering, Clemson University, 91 Technology Drive, Advanced Materials Research Laboratory (AMRL), Room 149, Anderson, Clemson, SC 29625, USA
bPolymer Engineering Department, Amirkabir University of Technology, Tehran, Iran
cIran Polymer and Petrochemical Institute, Tehran, Iran
Available online 8 June 2008.
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Abstract
The aims of this work were synthesis of rod shaped nano-hydroxyapatite (nHAP) and fabrication of novel nano-hydroxyapatite/poly(l-lactide acid) (nHAP/PLLA) composite scaffold. In the first step, the identification and morphology of chemically synthesized nHAP particles were determined by XRD, EDX, FTIR and SEM analyses. The rod shaped nHAP particles with an average size of approximately 37–65 nm in width and 100–400 nm in length were found similar to natural bone apatite in terms of chemical composition and structural morphology. In the second step, nHAP and micro sized HAP (mHAP) particles were used to fabricate HAP filled PLLA (HAP/PLLA) composites scaffolds using thermally induced phase separation method. The porosity of scaffolds was up to 85.06% and their average macropore diameter was in the range of 64–175 μm. FTIR and XRD analyses showed some molecular interactions and chemical linkages between HAP particles and PLLA matrix. The compressive strength of nanocomposite scaffolds could high up to 14.9 MPa while those of pure PLLA and microcomposite scaffolds were 1.79 and 13.68 MPa, respectively. The cell affinity and biocompatibility of the nanocomposite scaffold were found to be higher than those of pure PLLA and microcomposite scaffolds. Following the results, the newly developed nHAP/PLLA composite scaffold is comparable with cancellous bone in terms of microstructure and mechanical strength, so it may be considered for bone tissue engineering applications.
Keywords: Nanoparticle; Hydroxyapatite; Bone tissue engineering
Fig. 1. FTIR spectra of nHAP/PLLA composite (a) nHAP (b) pure PLLA (c).
Fig. 2. FTIR spectra of mHAP/PLLA composite (a) mHAP (b) pure PLLA (c).
Fig. 3. Typical EDX spectrum of the synthetic nHAP rods.
Fig. 4. XRD pattern of pure PLLA (a) nHAP (b), nHAP/PLLA composite (c).
Fig. 5. XRD pattern of pure PLLA (a) mHAP (b), mHAP/PLLA composite (c).
Fig. 6. SEM micrographs of the synthetic nHAP rods.
Fig. 7. SEM micrographs of pure PLLA, nHAP/PLLA and mHAP/PLLA scaffold. (a, b) Pure PLLA and cross-section; (c, d) nHAP/PLLA: 50/50 and cross-section; (e, f) nHAP/PLLA:50/50; (g, h) mHAP/PLLA:50/50 scaffold.
Fig. 8. Porosity of scaffolds, (1) pure PLLA, (2) nHAP/PLLA and (3) mHAP/PLLA scaffolds.
Fig. 9. Compressive modulus and strength of the fabricated scaffolds, Error bars represent means ±SD for n = 5 (*P < 0.05).
Fig. 10. Optical microscopy photographs of the colored MSCs (H&E staining) attached to the (a) pure PLLA, (b) mHAP/PLLA and (c) nHAP/PLLA.
Table 1.
Characteristic wavenumbers of nHAP, pure PLLA and nHAP/PLLA
