A Hybrid Laser/Aerosol Method for the Synthesis of Porous Nanostructured Calcium Phosphate Materials for Bone Tissue Eng
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A Hybrid Laser/Aerosol Method for the Synthesis of Porous Nanostructured Calcium Phosphate Materials for Bone Tissue Engineering Applications Shatoya Brown, Hyunbin Kim, Renato P. Camata Department of Physics, University of Alabama at Birmingham, Birmingham, AL 35294, U.S.A. ABSTRACT We present a new synthesis method based on laser generation and processing of aerosol particles that can produce calcium phosphate coatings in a porous nanostructured configuration. The process uses laser ablation of crystalline hydroxyapatite targets to produce a calcium phosphate aerosol comprising micro- and nanoparticles that are processed and deposited on metallic substrates under well-controlled temperature and ambient conditions, creating a microporous calcium phosphate network suitable for growth of biogenic calcium phosphate materials. Laser ablation is carried out using a KrF excimer laser at fluences between 0.4 J/cm2 and 2.8 J/cm2 and temperatures ranging from 500°C to 760°C. X-ray diffraction and scanning electron microscopy measurements on samples deposited above 750°C show that the obtained material is crystalline hydroxyapatite with good mechanical stability. Its microstructure features a porous framework of partially sintered microparticles surrounded by nanoparticulate material. INTRODUCTION Engineering and regeneration of bone tissue remains an outstanding problem in medicine and dentistry [1]. Recent studies show that nanophase materials are promising substrates for bone tissue engineering. Enhanced osteoblast functions have been reported in experiments carried out on nanostructured substrates based on ceramic [2], metallic [3], and carbon-based materials [4]. Nanostructured calcium phosphate bioceramics comprising mixtures of resorbable and nonresorbable calcium phosphate phases are of particular interest in this context because, in addition to their nanoscale morphology, they offer other useful pathways for stimulation of biological activity through their controllable dissolution behavior [5]. Laser methods such as pulsed laser deposition have demonstrated excellent control over the phase composition and microstructure of coatings of these mixtures, establishing them as suitable bioceramic substrates for bone tissue engineering research [6]. In this study we present a novel laser/aerosol method for synthesis of calcium phosphate materials capable of producing coatings with a porous nanostructured configuration. The process may also be Laser Beam scalable for calcium phosphate scaffold fabrication. Laser ablation of solids in background gases is known to Calcium Phosphate Gas flow produce particulates with a broad range of sizes and Aerosol properties [7]. These particulates may form as a result of Hydroxyapatite Target different energy relaxation mechanisms that take place Product aerosol can be: Deposited, Processed, following laser-solid interactions. Processes as varied as Size Classified, etc. vaporization followed by homogeneous gas phase nucleation Figure 1. Illustration of how a and coagulation gro
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