Hydroxyapatite nanorods/poly(vinyl pyrolidone) composite nanofibers, arrays and three-dimensional fabrics: Electrospun preparation and transformation to hydroxyapatite nanostructures Feng Chen, Qi-Li Tang, Ying-Jie Zhu * , Ke-Wei Wang, Mei-Li Zhang, Wan-Yin Zhai, Jiang Chang State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, People’s Republic of China article info Article history: Received 16 October 2009 Received in revised form 12 January 2010 Accepted 10 February 2010 Available online 16 February 2010 Keywords: Hydroxyapatite Electrospinning Nanofiber Nanorod Porous scaffold abstract Electrospinning has been recognized as an efficient technique for fabricating polymer nanofibrous bioma- terials. However, the study of electrospun inorganic biomaterials with well-designed three-dimensional (3-D) structures is still limited and little reported. In this study hydroxyapatite (HAp) nanorods with an average diameter of 7 nm and length of 27 nm were synthesized through a simple precipitation method and used for the fabrication of inorganic/organic [poly(vinyl pyrolidone) (PVP)] composite nanof- ibers by electrospinning in ethanol solution. 3-D fabrics and aligned nanofiber arrays of the HAp nano- rods/PVP composite were obtained as precursors. Thereafter, 3-D single phase HAp fabrics, tubular structures and aligned nanofiber arrays were obtained after thermal treatment of the corresponding com- posite precursors. Cytotoxicity experiments indicated that the HAp fabric scaffold had good biocompat- ibility. In vitro experiments showed that mesenchymal stem cells could attach to the HAp fabric scaffold after culture for 24 h. Ó 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. 1. Introduction Bone is a multiphase composite, with the main constituents of bone being collagen matrix and assembled hydroxyapatite (HAp) crystals [Ca 10 (PO 4 ) 6 (OH) 2 ]. HAp is the major inorganic constituent in human bone [1]. Synthetic HAp particles, films, coatings and porous skeletons with high biocompatibility are widely used in various biomedical applications [2]. Numbers of methods have been used for the synthesis of HAp, such as the wet chemical, mec- hano-chemical [3,4] and sol–gel methods [5,6]. HAp materials with different morphologies, including nanorods [7], plate-like nano- crystals [8], nanoparticles [9] and three-dimensional (3-D) struc- tures [10–13] have been synthesized. They can be used as a kind of ideal biomaterial for application in tissue engineering, drug/gene delivery systems and other fields [14–16]. Electrospinning has been recognized as an efficient technique for fabricating polymer nanofibers which can be widely used in biomedical areas [17,18]. A great number of polymer and compos- ite nanofibers have been prepared by electrospinning [19]. Recent developments in fiber electrospinning have shown that it is a promising way to produce future advanced composite systems. For instance, nanofibers are ideally suited to form a scaffold on which multi-functional components can be hierarchically orga- nized [20]. Electrospun fibers can also form well-designed patterns with complex ordered architectures using patterned conductive collectors [21,22]. Cell adhesion, growth and biomineralization on hybrid membranes are usually better than on pure polymer membranes [23–25]. However, investigations on electrospun inor- ganic biomaterials with well-designed 3-D structures are still lim- ited and little reported. However, the production of non-woven HAp fibers by electrospinning using a solution containing polyvinyl alcohol has been reported [26,27]. In this study HAp nanorods were synthesized through a simple precipitation method and then incorporated into PVP nanofibers to form HAp nanorods/PVP composite nanofibers through electros- pinning. 3-D fabrics with different shapes and aligned nanofiber arrays of the HAp nanorods/PVP composite were obtained by changing the collectors used during electrospinning. 3-D fabrics, tubular structures and aligned nanofiber arrays of single phase HAp were obtained by thermal treatment of corresponding com- posite precursors. Cytotoxicity experiments indicated that a HAp fabric scaffold had good biocompatibility. 2. Experimental section All chemicals were analytical grade reagents and were used as received, without further purification. For the preparation of HAp 1742-7061/$ - see front matter Ó 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.actbio.2010.02.015 * Corresponding author. Tel.: +86 21 52412616; fax: +86 21 52413122. E-mail address: y.j.zhu@mail.sic.ac.cn (Y.-J. Zhu). Acta Biomaterialia 6 (2010) 3013–3020 Contents lists available at ScienceDirect Acta Biomaterialia journal homepage: www.elsevier.com/locate/actabiomat