Development of Porous Nano-Hydroxyapatite from Austromegabalanus psittacus Marine Species Using Camphor and Wheat Flour as Pore Formers

Nano-hydroxyapatite (Ca-10 (PO4)(6)(OH)(2) exhibiting potential biocompatibility and compositional similarity to natural bone leads to the clinical solution/substitute to diseased/damaged parts of bone due to trauma. Porous bio active nano-hydroxyapatite can bond with host cell/tissue as implant. Abundant marine sources can be used to develop biocompatible material though novel chemical method. Marine resources, like skeletons of shells, corals, oysters, fish bones etc., are composed of calcium compound in the form of aragonite/calcite/veterite (calcium carbonate). Austromegabalanus psittacus has been opted for extraction of hydroxyapatite. Calcined aragonite mixed with distilled water and ortho phosphoric acid accordingly while maintaining the stoichiometric ratio of Ca/P equal to 1.67. Crystallite size of 62 nm was obtained using X-ray diffraction. Fourier transform infrared spectroscopy confirms the presence of all characteristic bonds of hydroxyapatite, namely PO43- distinguishable peak in the spectra. Porous hydroxyapatite based biomaterials having interconnected pores, are suitable for biological implants, such as bone tissue growth and vascularization: was developed with the help of pore former, camphor and wheat flour, with a weight percentage of 10, 20, 30, 40 and 50 to hydroxyapatite. Hydraulic pressed porous hydroxyapatite pellets were sintered at 1100 degrees C with a controlled heating (5 degrees C/min). Porous hydroxyapatite surface morphology shows interconnected pores of size 0.89 +/- 0 .24 mu m and near hexagonal shaped grins of size 1.85 +/- 0.69 mu m. Sintered hydroxyapatite is composed of irregular polygonal shaped grains with interconnected pores. In comparison with camphor, wheat flour emerges as a good pore former in terms of porosity of 45% obtained with the addition of 10 weight% without losing strength like, compressive strength 13.5 N/mm(2) and Modulus of elasticity, 1.3 GPa. Without addition of pore former, sintered hydroxyapatite exhibits compressive strength 55 N/mm(2) and modulus of elasticity 4 GPa. Porous nano-hydroxyapatite could have suitable applications as implants for the repair/replacement of defective bone

Low Temperature Development of Nano-Hydroxyapatite from Austromegabalanus psittacus, Star fish and Sea urchin

The study focuses the preparation and characterization (physico-chemical and mechanical) of hydroxyapatite Ca-10(PO4)(6)(OH)(2)] (HAp) from naturally occurring dead marine species widely available in Arabian sea shore; namely Austromegabalanus psittacus, star fish (Asteroidea) and sea urchin (Echinoidea). All three marine species were found to be source of calcium carbonate in the form of aragonite (calcite) that crystallize in an organic matrix. The calcined aragonite was converted to nano-sized hydroxyapatite powder by chemical reaction with Ortho-phosphoric acid while maintaining stoichiometry, Ca/P = 1.67 at 80 degrees C. It was found from XRD that the powders were composed of pure HAp with average crystallite size of 10 nm. SEM, on the other hand, revealed nano-rod like elongated structures having a length in the range of 100 to 700 nm with an aspect ratio of 3.5. Further, the HAp powders were used to prepare cylindrical pellet samples by uni-axial pressing, sintered at 1100 degrees C temperature, made flat-parallel, polished and used finally for assessment of elastic modulus by compression test method. Primary results showed typical elastic modulus of pellets from Austromegabalanus psittacus is 3 GPa, star fish 2.1 GPa and sea urchin 2.3 GPa (L/D = 1.3 and strain rate = 0.01 mm/s). Thus, the powder synthesized from marine source could be a potential alternative for development of structural bio-ceramics and also can be used as scaffolds for bone or dental implants, because of its easy and economical fabrication. (C) 2017 Elsevier Ltd. All rights reserved