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The superdiamagnetic effect of magnetic fields on one and two component multilamellar liposomes
Abstract:
For multilamella vesicles of DMPC, DPPC, DSPC, binary mixtures of DMPC-DPPC, DMPC-DSPC, DMPC-DPPE, DOPC and egg lecithin, the optical turbidity decreases significantly on the application of a magnetic field in excess of about 0.2 T, provided that the temperature is above the pretransition value. The turbidity reaches a limiting value for magnetic fields of about 2 T. The effect is attributed to augmentation of the diamagnetic anisotropy of the lipid molecules by clustering within the bilayer, with consequent orientation of either the individual 'superdiamagnetic' clusters or the whole liposome. It is suggested that, since most animal cell membranes are largely in the liquid crystalline phase, it is possible that homogeneous magnetic fields as low as 0.2 T may cause biologically significant changes within the membrane.
Insights
Magnetic fields significantly decrease optical turbidity in lipid vesicles above their pretransition temperature. This effect, observed in various lipid compositions, suggests potential biological impacts on cell membranes.
Area of Science:
- Lipid biophysics
- Membrane science
- Magnetohydrodynamics
Background:
- Multilamellar vesicles (MLVs) composed of phospholipids are model systems for biological membranes.
- The behavior of lipid bilayers under external stimuli, such as magnetic fields, is crucial for understanding membrane function.
- Diamagnetic anisotropy plays a role in the orientation of molecules in magnetic fields.
Purpose of the Study:
- To investigate the effect of magnetic fields on the optical turbidity of various lipid vesicles.
- To determine the magnetic field strength and temperature dependence of this effect.
- To explore the potential biological implications of magnetic field interactions with cell membranes.
Main Methods:
- Preparation of multilamellar vesicles from various phospholipid compositions (DMPC, DPPC, DSPC, DOPC, DPPE, egg lecithin) and their binary mixtures.
- Measurement of optical turbidity of vesicle suspensions under varying magnetic field strengths (0.2 T to 2 T) and temperatures relative to the pretransition temperature.
- Analysis of turbidity changes to infer molecular behavior and liposome orientation.
Main Results:
- A significant decrease in optical turbidity was observed for all tested lipid vesicles above their pretransition temperature when subjected to magnetic fields exceeding 0.2 T.
- Turbidity reached a plateau at approximately 2 T, indicating saturation of the magnetic field effect.
- The observed effect was attributed to the augmentation of diamagnetic anisotropy, leading to clustering and orientation of lipid molecules or entire liposomes.
Conclusions:
- Homogeneous magnetic fields, even as low as 0.2 T, can induce significant changes in lipid vesicle structure and orientation.
- The findings suggest that biological membranes, primarily in the liquid crystalline phase, may undergo biologically relevant alterations in response to similar magnetic field strengths.
- This research highlights a novel mechanism for magnetic field interaction with biological membranes, with potential implications for understanding cellular responses to magnetic stimuli.