Spectrofluorimetry is utilized as a novel real time non-invasive optical assay to investigate whether the exposure of bovine serum albumin (BSA) to extremely low frequency (ELF) and radio frequency (RF) electromagnetic (EM) fields causes conformational changes in the protein distinct from those due to heating alone. Such conformational changes would alter the protein's fluorescence spectrum, and could indicate a potential for EM induced altered biological activity of proteins in-vivo. The development of both the ELF and RF exposure system are described, discussed and evaluated. Since ELF electric fields do not exhibit propagation phenomena within the dimensions of the apparatus, a quasi-static approach is taken and a stainless steel parallel-plate exposure system is designed in a cuvette. While at RF, FDTD software is employed to facilitate a TEM cell based exposure system evaluation and optimization, and also to provide preliminary SAR distributions in the BSA sample as a control for future experimental measurements. The sensitivity of the systemic methodology (including the statistical analysis method) is demonstrated, indicating that the system is capable of detecting fluorescence changes as small as 0.032%. At ELF, the effects of six different high field strength 100Hz EM exposure paradigms at different temperatures on BSA conformational changes are presented and critically discussed. While at RF, four different 430MHz exposure paradigms are applied, with either intermittent or continuous bursts of TETRA or CW signals, at different average SAR levels. Statistical tests are used to analyse the experimental data. Periodical fluorescence oscillations are observed under both ELF and RF exposures, but their origins are considered to be convection currents due to unevenly distributed energy injections into the solution.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:574553 |
| Date | January 2012 |
| Creators | Liu, Wenchao |
| Publisher | University of Sheffield |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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