Electrospun Gelatin/Hydroxyapatite Nanocomposite Scaffolds for Bone Tissue Engineering
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Electrospun Gelatin/Hydroxyapatite Nanocomposite Scaffolds for Bone Tissue Engineering Shane Catledge1, Parul Tyagi1, Mark Koopman2, Andrei Stanishevsky1, and Yogesh K. Vohra1 1 Physics, University of Alabama at Birmingham, 1300 University Blvd., 310 Campbell Hall, Birmingham, AL, 35294-1170 2 Materials Science and Engineering, University of Alabama at Birmingham, BEC 1150 10th Ave. South, Birmingham, AL, 35294-4461 ABSTRACT Electrospun composite scaffolds were prepared by mixing gelatin with nanoparticles of hydroxyapatite (nanoHA) in 2,2,2-trifluoroethanol (TFE) solution. The fibrous composite scaffolds with nanoHA content from 0 to 40 wt% were compared in terms of structure and morphology via x-ray diffraction (XRD) and scanning electron microscopy (SEM). Results show that dispersion of nanoHA in the scaffolds is uniform for 0%, 10%, 20%, and 30% nanoHA content, but significant nanoHA agglomeration can be observed for scaffolds with 40% nanoHA. In order to study the effect of nanoHA content on mechanical properties at the nanoscale level, the fibrous scaffolds were pressed into dense pellets and tested by nanoindentation to determine Young’s modulus. Young’s modulus was found to increase linearly with nanoHA content, reaching unexpectedly high values of 10.2 ± 0.8 GPa. Results are compared with other polymer/HA composites including those made with polycaprolactone or collagen.
INTRODUCTION The search for successful bone analogue materials has led many researchers to prepare porous scaffolds with the intent to mimic as closely as possible the composition and/or structure of the extracellular matrix (ECM) of natural bone. Electrospun nanofibers can be used to create a scaffold in which both the morphological size scale and the chemical composition of the nanofibers are similar to that of ECM [1]. The majority of electrospun materials to date have been polymeric, including synthetic polymers (e.g., PLA, PCL, PGA and PLGA) [2-5], although natural proteins (primarily collagen [6]) have also been electrospun. Few studies have reported on the electrospinning of gelatin [7] or gelatin-based composite tissue scaffolds [8]. Addition of ceramic powders or sols (such as hydroxyapatite, HA) can be added to the polymer solution for electrospinning a composite particle-reinforced fiber with enhanced bioactivity and mechanical properties. The structural characteristics of gelatin in the solid state can be controlled at the stage of the gelatin structure formation in solution. This makes it possible to produce gelatin materials with markedly different structures [9]. In the present study, electrospun scaffolds comprised of gelatin with varying amounts of nanoHA particles were studied in terms of structural and mechanical properties. Scaffolds were uniaxially pressed into dense pellets for determination of Young’s modulus by nanoindentation.
EXPERIMENT Hydroxyapatite nanoparticles were synthesized by chemical precipitation at room temperature using Ca(OH) and H PO . The amounts of both chemicals were chosen to obt
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