Modified Polylactide Microfiber Scaffolds for Tissue Engineering
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Modified Polylactide Microfiber Scaffolds for Tissue Engineering R. Vera-Graziano, A. Maciel-Cerda, E.V. Moreno-Rondon, A. Ospina, and E.Y. GomezPachon. Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, Coyoacán, C.P. 04510, Distrito Federal, México. Corresponding author e-mail: [email protected] ABSTRACT Physical properties of porous membranes made of biocompatible and biodegradable polymers have been studied. The membranes are intended to be used as scaffolds for the regeneration of soft and hard tissues. Polylactides, polycaprolactone and some of their derivates are biocompatible as well as biodegradable materials, and are used for the preparation of nanofibers and nanoporous membranes. These membranes also have comparative advantages as cellular scaffolds for tissue engineering since they can be prepared to mimic the morphology of the extra cellular matrix. Chemical, physical, and biological properties of microfibers and scaffolds of polylactic acid (PLLA), as well as PLLA modified with hydroxyapatite nanoparticles and collagen (Col) are reported in this paper. The microfibers and the scaffolds were prepared by electrospinning. Morphology, diameter and porosity of the scaffold were determined by scanning electron microscopy and an image analyzer program. The microfibers are semicrystalline showing a shell of crystalline nanofibrils. The diameter of the fibers varied between 100 and 800 nm and the porous area of the membrane is between 60 and 80%. The mechanical properties of the microfibers and scaffolds were evaluated by microtensile tests and their behavior was simulated by using an original multiscale asymptotic homogenization model. Cultures of mesenchymal stem cells were used to evaluate their biological activity. Cell adhesion was observed in the modified PLLA scaffolds with grafted hydroxyapatite. INTRODUCTION Recent studies have led to the development of scaffolds made of micro and nanofibers of synthetic degradable polymers, obtained by electrospinning, for their use in tissue engineering. The effective use of these polymeric scaffolds is not only based on the morphology of the fibers, which can not only simulate the physical structure of the intracellular matrix, but also on the biochemical characteristics of the materials. PLLA is one of the world wide known biodegradable polymers; it is used in the biomedical area due to its biocompatibility, good mechanical properties and biodegradability. However, it is highly hydrophobic and lacks of groups that enhance interactions with bioactive molecules. On the other hand, bioceramics like hydroxyapatite and natural polymers like collagen show high bioactivity and hydrophilicity, which benefit cell adhesion, proliferation and cellular differentiation. However the scaffolds based on the physical blends of PLLA with these materials present several shortcomings like mechanical failure and some authors report that this behavior is due to the low miscibility of PLLA with collagen [1–3] and t
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