Magnetic field effects in model membrane systems
Magnetic field effects in model membrane systems
The aim of this research was to develop an understanding of some of the biological effects of magnetic fields following earlier observations in this laboratory of magnetically induced turbidity changes in vesicle suspensions. A study of the literature indicated that macroscopic vesicles orientation could play a significant role in such an effect and hence the initial approach taken was to study the orientational behaviour of vesicles suspensions in fields up to 1 T. To perform this study a phase gradient optical system was developed, based on a microscopic Schlieren technique, together with a specially designed thermostatic cell for holding the samples. No orientation effects were observed for any of the vesicle suspensions tried. It was therefore decided to examine the possible superdiamagnetic orientation effects within membranes suggested by Braganza et al. (Bioc. Biop. A. 801: 66 - 75 1984). The model system chosen for study was a lipid monolayer constrained at an air-water interface since this system offered the major advantage that the orientation of the magnetic field with respect to the monolayer normal was well defined. The results obtained, using the phospholipid dipalmitoyl phosphatidylcholine (DPPC), together with the estimated maximum cluster size indicate that any superdiamagnetic domains within a lipid monolayer are too small to produce a significant response to a magnetic field. Monolayer studies were also performed on the polypeptide polybenzylglutamate. The response to the field of this material was found to be substantially greater than that of the DPPC films due to the polymer's much larger diamagnetic anisotropy. Superdiamagnetic clustering provides an adequate description of the response in this case. A possible explanation for the reported turbidity changes by vesicle suspensions in a magnetic field is the magnetically induced deformation of vesicles. Such deformations would alter the vesicles scattering cross-sections and hence produce a change in the intensity of the transmitted light. Calculations show that turbidity is extremely sensitive even to minute changes in the scattering cross-section. It is still possible however that the suggested superdiamagnetic clusters exist within lipid bilayers but not in lipid monolayers. (DX84090)
University of Southampton
1988
Colbeck, Helen
(1988)
Magnetic field effects in model membrane systems.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
The aim of this research was to develop an understanding of some of the biological effects of magnetic fields following earlier observations in this laboratory of magnetically induced turbidity changes in vesicle suspensions. A study of the literature indicated that macroscopic vesicles orientation could play a significant role in such an effect and hence the initial approach taken was to study the orientational behaviour of vesicles suspensions in fields up to 1 T. To perform this study a phase gradient optical system was developed, based on a microscopic Schlieren technique, together with a specially designed thermostatic cell for holding the samples. No orientation effects were observed for any of the vesicle suspensions tried. It was therefore decided to examine the possible superdiamagnetic orientation effects within membranes suggested by Braganza et al. (Bioc. Biop. A. 801: 66 - 75 1984). The model system chosen for study was a lipid monolayer constrained at an air-water interface since this system offered the major advantage that the orientation of the magnetic field with respect to the monolayer normal was well defined. The results obtained, using the phospholipid dipalmitoyl phosphatidylcholine (DPPC), together with the estimated maximum cluster size indicate that any superdiamagnetic domains within a lipid monolayer are too small to produce a significant response to a magnetic field. Monolayer studies were also performed on the polypeptide polybenzylglutamate. The response to the field of this material was found to be substantially greater than that of the DPPC films due to the polymer's much larger diamagnetic anisotropy. Superdiamagnetic clustering provides an adequate description of the response in this case. A possible explanation for the reported turbidity changes by vesicle suspensions in a magnetic field is the magnetically induced deformation of vesicles. Such deformations would alter the vesicles scattering cross-sections and hence produce a change in the intensity of the transmitted light. Calculations show that turbidity is extremely sensitive even to minute changes in the scattering cross-section. It is still possible however that the suggested superdiamagnetic clusters exist within lipid bilayers but not in lipid monolayers. (DX84090)
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Published date: 1988
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Local EPrints ID: 460775
URI: http://eprints.soton.ac.uk/id/eprint/460775
PURE UUID: 3710e59b-66ac-465b-be52-0111814424b4
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Date deposited: 04 Jul 2022 18:29
Last modified: 04 Jul 2022 18:29
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Author:
Helen Colbeck
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