Seminars Archive

Magnetic fluids: drug delivery and x-ray spectroscopy characterization.

Abstract
Magnetic nanoparticles (MNPs) have been studied because of their unique properties and wide applicability in many different areas, such as fabrication of electronic components for the information storage, magnetic cards, recording devices. Recently MNPs gained a new interest also in biomedical sciences, since, when properly functionalized and dispersed in aqueous environment, they represent a promising alternative approach for drug delivery, hyperthermia, magnetic resonance imaging (MRI), tissue engineering, biosensing, biochemical separations, and bioanalysis. In this talk I will first discuss our recent results on a proof of principle series of experiment that showed a possible application of MNPs as drug release mechanism. We synthesized liposomes – which act as drug carriers – and we loaded them with two different CoFe2O4 NPs (citrate and oleic acid coated MNPs) – which act as a release mechanism - and we investigated the effect of the application of a low-frequency magnetic field (LF-AMF) on their permeability and release properties. We observed that exposure to AMF in the 0.1-10 Hz range and with 300 mT intensity induce a local thermal heating that causes the formation of pores at the membrane level of liposomes and the consequent release of a dye. A further step for the application of MNPs in biological environment is the evaluation of the chemical and magnetic behaviour of the MNPs in liquid solution. To this purpose a cell for liquid consisting of two Si3N4 membranes resistant to UHV conditions and transparent to x-ray photons was developed at IOM-CNR and soft x-ray spectroscopy experiments in liquids were carried out at BACH beamline at Elettra. The effect of hydration, surface charge (related to the pH of the solution) and citrate coatings on the electronic structure of CoFe2O4 NPs was evaluated by x-ray absorption spectroscopy (XAS) of the L3,2 edges of Fe and Co, and the K edge of O. X-ray magnetic circular dichroism (XMCD) measurements, performed during the commissioning of the new cryomagnet installed on BACH beamline, on a dry film of NPs show a strong magnetic dichroism at low T under high magnetic field.