Structure and permeability of magnetoliposomes loaded with hydrophobic magnetic nanoparticles in the presence of a low frequency magnetic field
ABSTRACT In this paper we describe the effect of a low frequency alternating magnetic field (LF-AMF) on the structure and permeability of magnetoliposomes, i.e. liposomes formulated in the presence of magnetic nanoparticles. Hydrophobic cobalt ferrite nanoparticles (CoFe(2)O(4)) coated with a shell of oleic acid were prepared, characterized and employed in the preparation of magnetoliposomes. The stability of the lipid bilayer after the application of an oscillating magnetic field was studied by means of Dynamic Light Scattering (DLS), Small Angle Scattering of X-rays (SAXS) and Differential Scanning Calorimetry (DSC). The enhancement of liposome permeability upon LF-AMF exposure was measured as the self-quenching decrease of the fluorescent molecule carboxyfluorescein (CF) entrapped in the liposome pool. Carboxyfluorescein leakage from magnetoliposomes was investigated as a function of field frequency, time of exposure to the magnetic field, and cobalt ferrite nanoparticles concentration. Kinetics of CF release from LF-AMF treated magnetoliposomes, monitored through the fluorescence intensity increase during time, highlights a slow release of CF during the first hours, followed by a faster release a few hours after the field treatment which leads to a complete leakage of CF. DSC provides insights about the effect of the LF-AMF treatment, showing that the first few hours correspond to a complete loss of the transition peak from the lamellar gel (L beta) phase to the liquid crystalline (L alpha) phase of the PC bilayers. These results suggest that the slow release takes place through the formation of local pores or defects at the membrane level, while the fast release corresponds to an increased permeability of the membrane that can be related to a structural change of the bilayer.
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ABSTRACT: Superparamagnetic iron oxide nanoparticles are used in a rapidly expanding number of research and practical applications in biotechnology and biomedicine. We highlight how recent developments in iron oxide nanoparticle design and understanding of nanoparticle membrane interactions have led to applications in magnetically triggered, liposome delivery vehicles with controlled structure. Nanoscale vesicles actuated by incorporated nanoparticles allow for controlling location and timing of compound release, which enables e.g. use of more potent drugs in drug delivery as the interaction with the right target is ensured. This review emphasizes recent results on the connection between nanoparticle design, vesicle assembly and the stability and release properties of the vesicles. While focused on lipid vesicles magnetically actuated through iron oxide nanoparticles, these insights are of general interest for the design of capsule and cell delivery systems for biotechnology controlled by nanoparticles.New Biotechnology 12/2014; DOI:10.1016/j.nbt.2014.12.002 · 2.11 Impact Factor
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ABSTRACT: Magnetic Fluid Hyperthermia (MFH) is an encouraging cancer treatment involving superparamagnetic nanoparticles coated with bio-active molecules. When placed in an oscillating magnetic field, the particles release heat into the tumor environment. The generally accepted mechanism of cell death is through hyperthermia, but it is plausible that destruction of the cell through mechanical means could also play a significant role. In this study, we examine mechanical disruption of a model cell membrane in the presence of a representative magnetic nanoparticle coating, the copolymer poly(ethylene oxide)poly(ethyl ethylene) (PEO-PEE). Our goal is to determine the effect of polymer properties on the mechanical rupture of a cell membrane under stress. Using dissipative particle dynamics, we create an interacting system of dipalmitoylphosphatidylcholine lipids, PEO-PEE polymers, and water and apply an incremental tension until bilayer rupture occurs. Our findings show that the optimal structure of the block copolymers to enhance rupture is relatively short polymers with a hydrophobic-hydrophilic-hydrophobic block structure containing a high hydrophilic content. Additionally, we compare the energy necessary to rupture a cell membrane with the magnetostatic energy of magnetic nanoparticles in MFH and our results indicate that nanoparticle sizes of the order of those currently used in standard MFH treatment produce enough energy for mechanical rupture, thus suggesting that mechanical means may be exploited in MFH to enhance the destruction of tumor cells. (C) 2011 Elsevier Ltd. All rights reserved.Chemical Engineering Science 03/2012; 71:400-408. DOI:10.1016/j.ces.2011.10.061 · 2.61 Impact Factor
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ABSTRACT: Magnetoliposomes, consisting of liposomes and magnetic nanoparticles (MNPs), have been tailored as very promising delivery vehicles in biotechnology and biomedicine applications. In this paper, liposomes with hydrophobic MNPs were prepared. The hydrophobic MNPs were successfully embedded in the lipid bilayer, which was proved by the results obtained from transmission electron microscope, atomic force microscope, differential scanning calorimetry and steady state fluorescence measurements. Moreover, systematic researches were carried out to investigate the effects of hydrophobic MNPs concentration on the morphology and microstructure of liposomes. The results show that the lipid bilayer was saturated with the hydrophobic MNPs when the mass ratio of MNPs to lipid reached 0.002.Chemistry and Physics of Lipids 06/2012; 165(5):563-70. DOI:10.1016/j.chemphyslip.2012.06.004 · 2.59 Impact Factor