Poly(DL-lactic-co-glycolic acid) sponge hybridized with collagen microsponges and deposited apatite particulates

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Abstract
A novel three-dimensional porous scaffold has been developed for bone tissue engineering by hybridizing synthetic poly(DL-lactic-co-glycolic acid) (PLGA), naturally derived collagen, and inorganic apatite. First, a porous PLGA sponge was prepared. Then, collagen microsponges were formed in the pores of the PLGA sponge. Finally, apatite particulates were deposited on the surfaces of the collagen microsponges in the pores of PLGA sponge. The PLGA-collagen sponge served as a template for apatite deposition, and the deposition was accomplished by alternate immersion of PLGA–collagen sponge in CaCl2 and Na2HPO4 aqueous solutions and centrifugation. The deposited particulates were small and scarce after one cycle of alternate immersion. Their number and size increased with the number of alternate immersion cycles. The surfaces of collagen microsponges were completely covered with apatite after three cycles of alternate immersion. The porosity of the hybrid sponge decreased gradually as the number of alternate immersion increased. Energy-dispersive spectroscopy analysis and X-ray diffraction spectra showed that the calcium-to-phosphorus molar ratio of the deposited particulates and the level of crystallinity increased with the number of alternate immersion cycles, and became almost the same as that of hydroxyapatite after four cycles of alternate immersion.The deposition process was controllable. Use of the PLGA sponge as a mechanical skeleton facilitated formation of the PLGA–collagen–apatite hybrid sponge into desired shapes and collagen microsponges facilitated the uniform deposition of apatite particulates throughout the sponge. The PLGA–collagen–apatite hybrid sponge would serve as a useful three-dimensional porous scaffold for bone tissue engineering. © 2001 John Wiley & Sons, Inc. J Biomed Mater Res 57: 8–14, 2001