Abstract
We report here a facile strategy to fabricate three-dimensional (3D) hydroxyapatite (HA) architectures with well-defined long continuous interconnected pores by using electrospinning and biomimetic mineralization. To this end, a polymeric nanofiber (NF) scaffold with well-defined architecture was fabricated by electrospinning, and bone morphogenetic protein 2 (BMP2) was then adsorbed onto the chemically modified NFs through bio-conjugation. The 3D nanoporous HA architecture was finally fabricated by biomimetic mineralization of the NF–BMP2 hybrid in simulated body fluids and subsequent dissolution of NFs in hexafluoroisopropanol. The formation of NF–BMP2 hybrid was identified by confocal laser scanning microscopy analysis. The crystal structure of HA crystals formed on NFs was examined by X-ray diffraction. The chemical composition and interconnected porous structure of the created 3D HA architectures were measured by X-ray photoelectron spectroscopy, focused ion beam scanning electron microscopy, and transmission electron microscopy, respectively. This bottom-up strategy based on electrospinning and biomimetic mineralization opens up a new way to prepare diverse porous HA-based hybrid materials and shows great potential in drug delivery, gene transfer and tissue engineering.
Highlights
Hydroxyapatite (HA) is an important inorganic material in the hard tissues of bone and teeth, and it is one of the few materials that can bind to bone tissue and promote bone substitution and repair.[1,2] There is increasing interest in the preparation and application of novel HA-based composite materials for bone substitutes.[3,4,5] It is well known that natural bone is porous and mainly composed of highly aligned HA crystals that bind onto the arranged type I collagen matrix.[6]
Paper the apatite produced on NF–bone morphogenetic protein 2 (BMP2) hybrids in SBF is a biological HA, which has been typically observed in those minerals created by biomimetic mineralization.[41,43]. Based on these X-ray photoelectron spectroscopy (XPS) data, we suggest that BMP2 can promote the nucleation and growth of HA crystals and 3D HA architectures can be created by incubating BMP2-modi ed NF meshes in SBF for about 7 days
The NF templates control the growth of minerals in the direction parallel to the NFs, while BMP2 controls the growth of created amorphous calcium phosphate (ACP) in the direction perpendicular to the NFs, which is similar to the formation of HA on carbon nanotube.[43]
Summary
Hydroxyapatite (HA) is an important inorganic material in the hard tissues of bone and teeth, and it is one of the few materials that can bind to bone tissue and promote bone substitution and repair.[1,2] There is increasing interest in the preparation and application of novel HA-based composite materials for bone substitutes.[3,4,5] It is well known that natural bone is porous and mainly composed of highly aligned HA crystals that bind onto the arranged type I collagen matrix.[6]. We have developed a method to prepare uniaxially and biaxially oriented electrospun ber mats, and with our improved electrospun apparatus ber mats with designed ber assembly and controlled ber spacing have been obtained.[26,27] Based on our previous studies and inspired by Liu's report,[25,26,27] we developed a new bottom-up strategy to prepare 3D HA architectures with well-de ned long continuous interconnected pores by using electrospinning and biomimetic mineralization. To the best of our knowledge, it is the rst report to create interconnected porous 3D HA architectures with the electrospun biaxially oriented polymer NF scaffolds. We utilized a biocompatible bone protein (BMP2) to improve the efficiency of biomimetic mineralization, and HA crystals were formed on NF–BMP2 architectures in normal SBF solution We utilized a biocompatible bone protein (BMP2) to improve the efficiency of biomimetic mineralization, and HA crystals were formed on NF–BMP2 architectures in normal SBF solution (instead of 10-fold-concentrated SBF in ref. 25) quickly
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