ELECTROSPINN1NG OF NANOCOMPOSITE SCAFFOLDS FOR BONE TISSUE ENGINEERING: EMITTING ELECTRODE POLARITY AND CHARGE RETENTION

摘要

Electrospinning is a simple and versatile technique for producing ultrafine fibers for many applications including tissue engineering. Most electrospinning studies conducted by researchers around the world have been using high positive voltages [i.e., positive voltage electrospinning (PVES)] and negative voltage electrospinning (NVES) has been rarely investigated. There was virtually no report on NVES of tissue engineering scaffolds until recently. However, fibrous scaffolds made by NVES, which can retain negative charges, may elicit desirable cell responses than fibrous scaffolds made by PVES in terms of cell attachment, proliferation and differentiation. The current study investigated the formation and characteristics of fibrous poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) polymer scaffolds and fibrous carbonated hydroxyapatite (CHA)/PHBV nanocomposite scaffolds under NVES. PVES of PHBV and CHA/PHBV scaffolds was also performed for comparisons. For fabricating fibrous CHA/PHBV nanocomposite scaffolds, CHA nanospheres were first synthesized using a nanoemulsion process and the nanospheres were dispersed in a PHBV solution under ultrasonication for electrospinning. The scaffolds obtained were characterized in terms of fiber diameter, morphology and microstructure and scaffold wettability, charge bearing ability and charge retention. For the biological study, cell culture experiments were performed using a human osteoblastic-like cell line (SaOS-2). It was found that CHA nanospheres were evenly distributed in and along CHA/PHBV nanocomposite fibers. Compared with PHBV polymer scaffolds, CHA/PHBV nanocomposite scaffolds exhibited better wettability. Both types of scaffolds retained detectable residual charges for considerable times and possessed similar charge decay profiles. Although the scaffolds facilitated the proliferation and spreading of SaOS-2 cells, CHA/PHBV nanocomposite scaffolds resulted in much higher expression of alkaline phosphatase (ALP) activity of SaOS-2 cells than PHBV polymer scaffolds.