# Electrospun Porous PDLLA Fiber Membrane Coated with nHA
## 1 Introduction  
Tissue defects arising from trauma, tumor or other diseases already lead to a large number of tissue-repair operations being performed worldwide every year, causing extensive physical and mental suffering for patients [1; 2]. At present, the tissue graft for tissue repair is transplanted from another part of the recipient's body or by allografts. The shortage of tissue graft donors and the significant post-operative morbidity have been major problems in tissue grafting solutions [2; 3]. Tissue engineering has provided a new approach for tissue repair. Once the autologous cells take hold and grow on the scaffold, the tissue engineering scaffold can be transplanted into the patient without fearof rejection. Furthermore, the tissue repair is not limited by an insufficient supply of tissue donor tissue or by donor morbidity risks [4; 5].  
One of the core technologies intrinsic to tissue engineering is the construction of an engineering scaffold, which focuses on materials and structures of scaffolds for cell seeding and in vitro or in vivo culturing. The scaffolds should not only possess excellent biocompatibility [6; 7], but also have a reasonable three-dimensional structure [8], surface wettability [9] and so on [10; 11; 12]. Therefore, tissue engineering scaffolds with excellent performance are interesting to many researchers [13; 14; 15]. In recent years, polylactide/hydroxyapatite (PLA/HA) composites specially prepared by electrospinning have been an excellent tissue engineering scaffold [16; 17; 18; 19]. The PLA-based biopolymer fiber framework has a controllable 3-D network structure, good mechanical behavior, biocompatibility and biodegradability [20; 21]. Hydrophilic HA acts to improve the water wettability, induce the cellular adherence and provide additional functionality [22; 23; 24]. Nevertheless, there are many HA particles distributed on the inside of PLA-based nanofiber, prepared by blend electrospinning, which could not effectively improve the water wettability and induce the cellular adherence. To overcome this issue and to increase the exposed area of the HAs to cells, new processing strategies are required.  
In this paper, a novel method is presented for the preparation of poly-D-L-lactic acid (PDLLA) fibrous membrane embedded with nano-hydroxyapatite (nHA) particles for tissue engineering scaffold. Almost all the nHA particles are observed to distribute on the surface of new type composite fibers, which could significantly improve the water wettability and induce the cellular adherence. Two steps were involved in this method. First, a phase separation method was employed to prepare the porous PDLLA fibrous membrane. Second, the PDLLA/nHA composite fibrous membranes were fabricated by immersing the porous PDLLA into nHA dispersions, which were then shrunk in absolute ethanol. Composite fibrous mats were characterized for their surface topography, nHA content, surface wettability and mechanical behavior, amongst other features. Finally, cell proliferation experiments using rabbit chondrocytes were performed on the PDLLA/nHA composite membrane, bringing about potential applications in tissue engineering.