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Please use this identifier to cite or link to this item: http://hdl.handle.net/1860/220

Title: Carbon nanotube based nanocomposite fibril for cartilage regeneration
Authors: Khan, Sakina Sharmin
Keywords: Nanostructure materials;Cartilage -- Regeneration
Issue Date: 24-Sep-2003
Abstract: This research was designed to evaluate the feasibility of Nanotube based nano-composite fibril for cartilage by characterizing the morphological and physical properties of the scaffold and by evaluating in vitro cell proliferation of chondrocytes on the scaffold. The unique physical properties of carbon nanotube (CNT) at nanolevel allow significant application of nanotubes in every conceivable area of structural engineering. The application of nanotubes in the biomedical area is still very much limited. Since, all lives are carbon based and nanotubes are solely made of carbon with a similar scale size of DNA-the molecule of life, promising possibilities can be expected by introducing them to reinforce tissue engineered scaffolds. Matrix was fabricated by electrospinning to develop a 3-dimensional assembly of nanofibers. Use of biocompatible and biodegradable polymer Poly-L-lactic acid ensured nontoxic response of the body towards the scaffold and complete elimination of the polymer from the body after the regeneration of the natural tissue. The nanotubes were purified, dispersed and mixed with the polymer solution for being electrospun into non-woven fabric with interconnected pores. The porosity and pore size were optimized by changing the parameters during electrospinning. Spectroscopic study using Raman spectrometer was used to detect the presence of nanotubes in the samples. Transmission electron microscopy was performed in order to study the alignment of the nanotubes in the polymer fibers and visualize the presence of crystalline lattice fringe of the nanotubes. Scanning electron microscopy was used to analyze the pore size porosity and the fiber diameter of the over all structure while Atomic force microscopy was performed to evaluate the topography of individual CNT containing fibers. The integrity of the nanotube-nanofiber constructs were evaluated by testing the tensile modulus using an Instron machine. Electrical conductivity of the samples was tested using four-probe device. During each characterization, one control sample of PLA nanofibers Calf articular chondrocytes were used for in vitro cell study. The viability of the cells onto the scaffold and their hyperplastic activity was tested. SEM images were taken at day 7 and 14 to evaluate the cell morphology, the attachment and spreading of cells on the scaffold and formation of intercellular bridge. Results from characterization revealed that the CNT/PLA scaffold was a novel construct with optimum pore size for cell-migration and optimum porosity similar to natural tissue to allow tissue regeneration. Nanotubes were well arranged in the nanofibers, providing a modulus of the scaffold within the range of modulus of the natural cartilage and electrical conductivity same as semi-conductor materials. In vitro cell study showed the presence of living chondrocytes onto the scaffold using the MTT assay. The ability of the cells to produce and secrete Procollagen II on the scaffold showed convincing evidence of the cell-differentiation within the scaffold. SEM study revealed that there were migration of cells on the deeper part of the structures with a period of one week and the scaffold surface was covered by cells leaving little or no pores open. It can be concluded that, the nano-composite scaffold with its nano-scale size, 3-dimensional structure, optimum pore size and porosity, high integrity, electrical conductivity is a highly suitable scaffold for load-bearing cartilage that are subjected to high tensile and compressive stress. The 2-dimensional bending flexibility of graphite sheets in the nanotube walls are expected to allow gliding movement on the scaffold during locomotion. The ability to shape the structure readily allows the use of the scaffold in areas with difficult access such as, craniofacial injury.
URI: http://dspace.library.drexel.edu/handle/1860/220
Appears in Collections:Drexel Theses and Dissertations

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