Hydroxyapatite (HA) nanoparticle-collagen composite materials with various HA/collagen weight ratios were prepared from HA/collagen dispersions using the solution deposition and electrospinning with static or rotating collectors. The composites with nanoparticle HA to collagen weight ratio of 80:20 can be easily prepared in the solution deposition approach, whereas in the electrospun fibrous composites it was possible to reach a maximum HA/collagen weight ratio of 30:70 while maintaining a good fibrous structure. The structure, surface morphology, and nanoindentation properties of these nanoparticle HA/collagen composites with different microarchitectures were investigated. The values from 0.2 GPa to 20 GPa for nanoindentation Young's modulus and from 25 MPa to 500 MPa for hardness, were obtained depending on the fabrication technique, composition, and microarchitecture of the composites. It was observed that the nanoindentation Young's modulus and hardness of the HA/collagen composite materials seem to achieve maximum values for 45-60% HA content by weight.
The polymer/bioceramic composite materials attract much attention for the development of bioresorbable implants and tissue engineering scaffolds. Hydroxyapatite (HA) is the most commonly used bioceramic material due to its similarity to the major mineral component of the hard tissue. We synthesized carbonated and Mg-substituted HA nanocrystals with various concentrations of CO32− and Mg2+ ions by chemical precipitation in the range of the process temperatures from 25 °C to 100 °C.The HA nanocrystals were mixed with several polymeric materials (PCL, PLA, PVA, collagen) to fabricate bulk and nanofiber polymer/HA nanoparticle composites with the HA loading up to 80 % by weight. The HA nanocrystals and polymer/HA composites were characterized by X-ray diffraction, FT-IR spectroscopy, scanning electron and atomic force microscopy. Mechanical properties of the composites were investigated using nanoindentation technique.
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