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Mater. Res. Soc. Symp. Proc. Vol. 1418  © 2012 Materials Research Society
           DOI: 10.1557/opl.2012.395

             Novel Electrospun Bicomponent Scaffolds for Bone Tissue Engineering: Fabrication,
                       Characterization and Sustained Release of Growth Factor

                    1
                                           2
           Chong Wang  , Min Wang  1, * , Xiao-Yan Yuan
           1
            Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road
            Hong Kong
           2  School of Materials Science and Engineering, Tianjin University, Tianjin 300072, China
           *  Corresponding author: memwang@hku.hk

           ABSTRACT

              Electrospinning is a versatile technique for fabricating three-dimensional (3D) nanofibrous
           scaffolds and the scaffolds have been found to  elicit desirable cellular behavior for tissue
           regeneration because the nanofibrous structures mimic the nanofibrous extracellular matrix
           (ECM) of biological tissues. From the material point of view, the ECM of bone is a nanofibrous
           nanocomposite consisting of an organic matrix  (mainly collagen) and inorganic bone apatite
           nanoparticles. Therefore, for bone tissue engineering scaffolds, it is natural to construct
           nanofibrous nanocomposites having a biodegradable polymer matrix and nanosized bioactive
           bioceramics. Our previous studies demonstrated: (1) electrospun nanocomposite fiber loaded
           with calcium phosphate (Ca-P) were osteoconductive and could promote osteoblastic cell
           proliferation and differentiation better than pure polymer fibers; (2) The controlled release of
           recombinant human bone morphogenetic protein (rhBMP-2) from scaffolds provided the
           scaffolds with desired osteoinductivity. In the current investigation, novel bicomponent scaffolds
           for bone tissue engineering were produced using our established dual-source dual-power
           electrospinning technique to achieve both osteoconductivity and osteoinductivity. In the
           bicomponent scaffolds, one fibrous component was electrospun Ca-P/PLGA nanocomposite
           fibers and the other component was emulsion electrospun PDLLA nanofibers incorporated with
           rhBMP-2. Through electrospinning optimization, both fibers were evenly distributed in
           bicomponent scaffolds. The mass ratio of rhBMP-2/PDLLA fibers to Ca-P/PLGA fibers in
           bicomponent scaffolds could be controlled using multiple syringes. The structure and
           morphology of mono- and bicomponent scaffolds were examined. The  in vitro release of
           rhBMP-2 from mono- and bicomponent scaffolds showed different release amount but similar
           release profile, exhibiting an initial burst release. Blending PDLLA with polyethylene glycol
           (PEG) could reduce the initial burst release of rhBMP-2.

           INTRODUCTION

              Due to an increased aging population as well as increased incidents of bone fractures, there
           is an increasing demand for bone tissue repair or regeneration. Tissue engineering, which uses
           biomaterials in concert with cells and biosignals, offers an alternative to autograft transplantation
           or prosthesis implantation bone  tissue repair/regeneration [1]. For scaffold-based bone tissue






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