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NANOSTRUCTURED BIOCOMPATIBLE SYSTEMS BASED ON MAGNETIC NANOPARTICLES AND STIMULI RESPONSIVE POLYMERS |
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Contract nr: 71-068 / 2007
Contact: Dr. Rodica Turcu |
Results
Stage I StageII StageIII StageIV Stage II
Biocompatible magnetic ferrofluids based on magnetite nanoparticles stabilized with saturated carboxyl acids C12 and C14, lauric acid (LA) and miristic acid (MA), were obtained. By covering the nanoparticle with a double layer shell, we will have the carboxyl group of the outer shell which is favorable to further bonding of a bioactive group. The mean magnetic diameter varies between 5.9nm and 7.4nm (30%) according to the nature of the surfactant and the filtration process used. Magnetic hydrogels based on PVA and NIPA were prepared by encapsulating the colloidal suspension of magnetic nanoparticles stabilized in ferrofluid, into the polymer’s network which is thermo or pH sensitive. It was observed that the ferrogels based on pNIPA, which have several hydrophilic groups in the molecular structure, present a higher increase of the volume than the PVA ferrogels. It was observed that the hydrogel has a relatively more ordered structure of the chains as the amount of reticular agent increased. EDX measurements evidenced a nearly uniform distribution of the nanoparticles in the ferrogel. The mean diameter of the magnetite nanoparticles within the ferrrogels, obtained by TEM, is 6-10nm. The same values were obtained by magnetogranulometric analysis. The superparamagnetic behavior was observed at all the samples of PVA and NIPA ferrogels. With the increase of the concentration of magnetic nanoparticles in the ferrogel’s synthesis process, it was observed an almost linear increase in the saturation magnetization of the ferrogels. This observation proves the efficient encapsulation of the nanoparticles in the polymeric gel. Mossbauer measurements evidenced a good dispersion degree in case of PVA and NIPA ferrogels. Mossbauer measurements at low temperatures evidenced the presence of magnetite, but don’t exclude the existence of some disordered magnetic phases/defects.
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