Hydroxyapatite Nanopowder Synthesis with a Programmed Resorption Rate

Dariusz Smoleń,Tadeusz Chudoba,Witold Łojkowski,Wojciech Święszkowski,Aleksandra Kedzierska,Kamil Sobczak,Krzysztof Jan Kurzydłowski,Stanisław Gierlotka

doi:10.1155/2012/841971

Abstract

A microwave, solvothermal synthesis of hydroxyapatite (HAp) nanopowder with a programmed material resorption rate was developed. The aqueous reaction solution was heated by a microwave radiation field with high energy density. The measurements included powder X-ray diffraction (PXRD) and the density, specific surface area (SSA), and chemical composition as specified by the inductively coupled plasma optical emission spectrometry technique (ICP-OES). The morphology and structure were investigated using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). A degradation test in accordance with norm ISO 10993-4 was conducted. The developed method enables control of the average grain size and chemical composition of the obtained HAp nanoparticles by regulating the microwave radiation time. As a consequence, it allows programming of the material degradation rate and makes possible an adjustment of the material activity in a human body to meet individual resorption rate needs. The authors synthesized a pure, fully crystalline hexagonal hydroxyapatite nanopowder with a specific surface area from 60 to almost 240 m2/g, a Ca/P molar ratio in the range of 1.57–1.67, and an average grain size from 6 nm to over 30 nm. A 28-day degradation test indicated that the material solubility ranged from 4 to 20 mg/dm3.

Highlights

The number of cases of bone defects requiring replacement has increased rapidly in recent years [1, 2]
A fully crystalline hydroxyapatite nanopowder with programmed solubility rate was successfully synthesized by a novel microwave solvothermal synthesis (MSS) method using high-density microwave radiation as a heating mechanism
The material degradation rate was regulated by the amount of applied microwave radiation, which determined the particle size and stoichiometry of the obtained hydroxyapatite nanopowder and enabled the material solubility to be programmed

Summary

Introduction

The number of cases of bone defects requiring replacement has increased rapidly in recent years [1, 2]. There is no solution presently available that overcomes the disadvantages and disabilities of current medical practices. Techniques are needed to repair large bone defects and to return patients to their previous quality of life. A primary difficulty is the lack of a proper material which enables the creation of bone scaffolds with the appropriate mechanical strength and a controllable resorption rate. Autografts are the clinical gold standard for bone replacement therapy. Autografts provide the primary factors for effective bone regeneration, but they impose a significant cost and risk [3,4,5]

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