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Bio-inspired calcium phosphate/biopolymer nanocomposite fibrous scaffolds for hard tissue regeneration

University of British Columbia

This study discloses an original process for making calcium phosphate (CaP)/biopolymer nanocomposite fibrous scaffolds by biomimetic in-situ synthesis and electrospinning. Electrospinning (ES) produces non-woven nanofibrous mesh structure with 3D interconnected pores and a high surface area by applying electrostatic force to polymer-based solution. The resulting topography of the scaffolds mimics the natural extracellular matrix of human tissues, with the potential application in tissue engineering, drug delivery, and wound dressing. We have demonstrated that the possibility of inclusion of CaP into biopolymer nanofibers, inspired by mineralized collagen fibrils in bone tissue, makes ES an attractive processing route for preparation of the nanocomposites for bone tissue regeneration. Two different nanocomposite fibers were explored; i) poly(lactic acid) (PLA) with dicalcium phosphate anhydrate (DCPA) and ii) alginate with hydroxyapatite (HAp). In-situ synthesized DCPA in non-aqueous PLA solution were electrospun into self-fused and intra-nano porous networks. Homogeneous dispersion of DCPA nanocrystallites in the PLA nanofibers was induced by controlling the interaction of Ca²+ ions and the carbonyl groups in PLA, providing nucleation sites for DCPA during the in-situ synthesis. It is shown that the nucleation and growth of HAp on electrospun alginate nanofibers was generated at the [–COO‾]–Ca²+–[–COO‾] linkage sites on electrospun alginate nanofibers impregnated with PO₄³‾ ions during cross-linking treatment of alginate. This novel in-situ synthesis developed in this work resulted in the uniform distribution of the CaP nanophases and avoided agglomeration of the inorganic nanoparticles fabricated by the conventional mechanical blending method. Rat calvarial osteoblasts were stably attached and proliferated faster on the CaP/biopolymer nanocomposites fibrous scaffolds than the pure polymer scaffolds, respectively. Mineralized bone-like nodules deposited after 6 weeks of seeding on DCPA/PLA scaffolds. The unique nanofibrous architectures combined with the CaP nanophases were engineered using ES and the novel biomimetic in-situ synthesis. It is anticipated that the nanocomposite systems mimicking the mineralized collagen fibrils in bone tissue could be advantageous in bone tissue regenerative medicine applications.

Text

2015-03-31

Attribution-NonCommercial-NoDerivs 2.5 Canada

http://hdl.handle.net/2429/52583

Materials Engineering

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/2.5/ca/