CUSTOMIZED NANOCOMPOSITE SCAFFOLDS FABRICATED VIA SELECTIVE LASER SINTERING FOR BONE TISSUE ENGINEERING - Intelligent Scaffolds for Tissue Engineering and Regenerative Medicine - page 935

purpose of reducing raw material consumption, Wiria et al. modi-
fied their SLS systemfor scaffold manufacture. 55
TheSLSprocessrequiresrawmaterialstobeinthepowderform
and of appropriate sizes. Therefore, for constructing PHBV-based
tissue engineering scaffolds via SLS, PHBV microspheres and Ca-
P/PHBVnanocompositemicrosphereswerefabricatedpriortoscaf-
foldfabrication.Ca-Pnanoparticleswerefirstlysynthesizedbyrapid
mixing of a Ca(NO 3 ) 2 · 4H 2 O acetone solution with a (NH 4 ) 2 HPO 4

aqueous solution. 56 With sizes in the range of 10-30 nm, the Ca-P
nanoparticles obtained were amorphous, as shown in Fig. 45.4, and
had a Ca:P molar ratio of about 1.5, which is similar to that of trical-
ciumphosphate, acommonlyusedbioactiveandbiodegradablebio-
ceramic for bone tissue repair. PHBV microspheres were produced
using the oil-in-water (O/W) emulsion solvent evaporation method.
The polymer was dissolved in chloroform at 50 ◦ C and then added
to an aqueous phase containing 1% PVA (w/v). The resulting emul-
sion was stirred at 600 rpm at room temperature until the solvent
evaporated. The microspheres obtained were filtered, washed, and
freeze-dried. Similarly, Ca-P/PHBV nanocomposite microspheres
containing Ca-P nanoparticles were fabricated using the S/O/W
emulsion solventevaporation method. 56
Both PHBV and Ca-P/PHBV microspheres were spherical in
shape, and the surface of PHBV microspheres had a rough-wrinkled
morphology (Fig. 45.4). The roughness of the PHBV microsphere
surfacewasprobablycausedbytherelativelyhighcrystallinityofthe
PHBV polymer. The Ca-P/PHBV nanocomposite microspheres pro-
duced had an average diameter of 46.34 m, as was measured by

a particle sizer, which was smaller than that of PHBV microspheres
(53.18

μ

μ

m). The decrease in size and a narrower size distribution
of Ca-P/PHBV nanocomposite microspheres were probably due to
Ca-Pnanoparticles,whichmayhaveactedasapickeringstabilizer 57
(co-emulsifier) during the fabrication of Ca-P/PHBV microspheres.
Similarly, Fujii et al. fabricated HA nanoparticle-coated PLLA via a
“pickering-type”emulsionrouteintheabsenceofanynormallyused
surfactants. 58 Materials with particle sizes in the range of 10-150
μ marepreferredfortheSLSprocess.Therefore,bothPHBVandCa-
P/PHBV microspheres were of suitable sizes for the SLS technology.
The Ca-P content of Ca-P/PHBV nanocomposite microspheres was