Polyurethane foam/nano hydroxyapatite composite as a suitable scaffold for bone tissue regeneration.

In bone tissue regeneration, the use of biomineralized scaffolds to create the 3D porous structure needed for well-fitting with defect size and appropriate cell interactions, is a promising alternative to autologous and heterologous bone grafts. Biomineralized polyurethane (PU) foams are here investigated as scaffold for bone tissue regeneration. Biomineralization of the foams was carried out by activation of PU surface by a two steps procedure performed for different times (1 to 4 weeks). Scaffolds were investigated for morphological, chemico-physical and mechanical properties, as well as for in vitro interaction with rat Bone Marrow Mesenchymal Stem Cells (BMSCs). Untreated and biomineralized PU samples showed a homogenous morphology and regular pore size (average Ø=407µm). Phase and structure of formed calcium phosphates (CaPs) layer onto the PU foam were analyzed by Fourier Transform Infrared spectroscopy and X-ray diffraction, proving the formation of bone-like nano hydroxyapatite. Biomineralization caused a significant increase of mechanical properties of treated foams compared to untreated ones. Biomineralization also affected the PU scaffold cytocompatibility providing a more appropriate surface for cell attachment and proliferation. Considering the obtained results, the proposed scaffold can be considered suitable for bone tissue regeneration.

In situ biomimetic synthesis and characterization of nano hydroxyapatite in gelatin matrix.

In this work, nano hydroxyapatite (nHAp) composites were synthesized via an in situ biomimetic process at room temperature by using gelatin as a template agent. Formation of hydroxyapatite nanoparticles and the effect of biopolymer concentration on the shape and morphology of the nHAp nanoparticles were confirmed and investigated by using X-ray diffraction (XRD), Fourier Transform Infrared spectroscopy (FT-IR), Scanning and Transmission Electron Microscopy (SEM and TEM). The results indicated that, the gelatin biopolymer as a template agent in the preparation batch has influences the size and morphology of the HAp nanocrystals precipitated in an aqueous solution of gelatin.

Biocompatibility evaluation of nano hydroxyapatite-starch biocomposites.

In this work, we report the synthesis and characterization of nano hydroxyapatite (nHAp) in the presence of starch matrix via a biomimetic process for in vitro biocompatibility evaluation. Characterization of the samples was carried out using X-ray diffraction (XRD) and Fourier Transform infrared spectroscopy (FT-IR). The Size and morphology of the nHAp samples were determined using scanning and transmission electron microscopy (SEM and TEM). The results show that, the shape and morphology of nHAp is influenced by the presence of starch as a template agent. It leads to formation of rod-like nHAp. Cell culture and MTT assays were performed for in vitro biocompatibility. They show that n-HAp can affect the proliferation of cells and the n-HAp/starch biocomposites have no negative effect on the cell morphology, viability and proliferation.

Laser induced fluorescence bands in the FT-Raman spectra of bioceramics.

A new fluorescence band at about 1930cm-1 has been observed in the FT-Raman spectra of some bioceramics. While a fluorescence band at about 760cm-1 has been already reported in the FT-Raman spectra of hydroxyapatite and related calcium phosphates, this new band is observed for the first time. This strong band is totally absent in the anti-Stokes side of the FT-Raman spectra and therefore has been assigned as a laser induced fluorescence band. It has been concluded that in recording FT-Raman spectra of minerals, all precautions about fluorescence bands should be considered, otherwise the FT-Raman spectra may well be misinterpreted.