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1236-SS08-51

Nanoparticle-based Calcium Phosphate Substrates: Gas Phase Synthesis and Potential Applications Parimal V. Bapat1, Rebecca Kraft1, Marco C. Bottino2 and Renato P. Camata1 1

Dept. of Physics, University of Alabama at Birmingham, Birmingham, AL 35294-1170, USA.

2

Dept. of Materials Science and Engineering, University of Alabama at Birmingham, Birmingham,

AL 35294-4461, USA ABSTRACT Emulating the ECM microenvironment of natural tissue and understanding how such an environment affects integrin function is a major goal of regenerative medicine and tissue engineering. In this work we have combined laser and aerosol techniques to create nanoengineered substrates comprising calcium phosphate nanoparticles of well controlled size on atomically flat SiO2 layers. In our process, gas suspended calcium phosphate nanoparticles are generated by ablation of a solid hydroxyapatite target inside a tube furnace at 800-900oC in presence of argon/H2O flow using a KrF excimer laser and deposited on a silicon substrate via electrostatic precipitation. Measurements reveal that our system is capable of synthesizing size selected calcium phosphate nanoparticles and the substrates created exhibit some physical characteristics that are similar to those found in the ECM of bone tissue. INTRODUCTION Cell adhesion processes are mediated by the integrin family of transmembrane glycoproteins. Integrins play a vital role in formation of focal adhesions, which anchor cells to the extracellular matrix (ECM) [1]. Over two dozen different integrins are known to be expressed in humans and contribute to the specific binding of cells to proteins of the ECM. Emulating the ECM microenvironment of natural tissue and understanding how such an environment affects integrin function is a major goal of regenerative medicine and tissue engineering [2]. Recent studies of cell behavior on surfaces patterned with gold nanoparticles and conjugated to RGD peptides show that integrin function and thereby cell migration and orientation can be controlled by how adhesive ligands are patterned and spaced on a surface [3]. The elucidation and exploitation of the basic mechanisms through which such chemical and topographical features determine cell behavior represent one of the most important challenges in biomaterials research. Calcium phosphates and especially hydroxyapatite [HA: Ca10(PO4)6(OH)2] are found in abundant proportions in bones and in tooth enamel. Synthetically grown calcium phosphates showing chemical and structural resemblance with naturally occurring biological materials have proven to be very useful in biological applications ranging from cements and coatings for prosthetic implants to substrates and scaffolds for bone tissue engineering [4,5,6,7,8]. More recently, significant research interest has been devoted to calcium phosphates in the form of nanoparticles because of their enhanced bioactivity and tunable dissolution behavior, which may provide new opportunities in bone tissue engineering applications. Furthermore, the ECM of bone featu