Hydroxyapatite/Polyvinyl Alcohol Composite <i>In Situ</i> Synthesis for Hydrogel Formation

Abstract

It is well known that polyvinyl alcohol hydrogel-based (PVA-H) biomaterials are promising materials for damaged articular cartilage replacement, but their application for bone tissue engineering is restricted due to insufficient mechanical properties. Thus, to meet the demands of the bone substitute material, PVA-H are reinforced with hydroxyapatite (HAp) crystals. The current research is focused on the preparation of nanosized hydroxyapatite/polyvinyl alcohol (n-HAp/PVA) composite material that mimics the microstructure and mechanical properties of natural bone tissue. The aim of this work is to determine the impact of various technological parameters of n-HAp/PVA composite in situ synthesis on the chemical purity of final product. Obtained results confirmed that the main inorganic phase of the composite material is HAp with an average crystallite size of 20.39 nm, however β-tricalcium phosphate (β-TCP) and CaO phases are also present. Obtained results showed that it is possible to decrease the amount of potentially harmful by-products, e.g. CaO in the composite material from 1.57wt% to 0.32wt% by increasing the homogenization speed of starting suspension from 400 rpm up to 7000 rpm, though the main influence on the obtained products chemical purity has 5wt% polyvinyl alcohol aqueous solution. Based on the results, it is concluded that the combination of starting suspension stirring temperature, homogenization speed and homogenization time of 23°C, 7000 rpm and 2 min, respectively, allows to obtain nanocomposite with the lowest amount of impurities (HAp: 98.08wt%; β-TCP: 1.60wt%; CaO: 0.32wt%).