The laser in biophysical and analytical chemistry: Investigating biophysical processes and dynamics, as well as analytical techniques, as applied to systems of biological and chemical relevance

dc.contributor.advisor Jacob W. Petrich
dc.contributor.author Ashby, Kyle
dc.contributor.department Chemistry
dc.date 2018-08-23T00:25:52.000
dc.date.accessioned 2020-06-30T07:22:50Z
dc.date.available 2020-06-30T07:22:50Z
dc.date.copyright Sat Jan 01 00:00:00 UTC 2000
dc.date.issued 2000-01-01
dc.description.abstract <p>The unique properties of the laser have permitted the investigation of important biological molecules and systems, and aided in the development of the F-Detector, important in the area of food safety. The laser offers narrow pulses of high peak power to probe chromophore interactions with micelles, protein structure and dynamics, excited-state photophysics, and selective fluorescence detection;Using the laser based time-correlated single photon counting technique, the effect of a surfactant on the fluorescence properties of indole, 1-methylindole, and 3-methylindole in aqueous solutions was investigated. 3-methylindole partitions very well into the Brij-35 micelle as indicated by the triple exponential fluorescence decays. An equilibrium constant of 2.6 x 104 M-1 was determined for the 3-methylindole/micelle interaction;Using the same time-resovled technique, tropomyosin mutants containing either tryptophan, 5-hydroxytryptophan, or 7-azatryptophan were expressed in Escherichia coli and their fluorescence properties studied;Utilizing fluorescence upconversion, measurements of hypericin and its methylated analog, O-hexamethoxyhypericin, which possesses no labile protons, confirm excited-state hydrogen atom transfer as the primary photophysical event in hypericin;Laser based pump-probe transient absorption spectroscopy was utilized to determine that the activation energies for excited-state hydrogen atom transfer of hypericin and hypocrellin are respectively, 0.044 +/- 0.008 and 2.12 +/- 0.070 kcal/mol. The low activation energies are consistent with the hydrogen atom transfer reactions being adiabatic;The laser based F-Detector was designed and built for selective detection of fecal and ingesta contamination on meat carcasses as they are processed. F420 was initially utilized as the fluorescent marker, but later investigations revealed the utility of pheophorbide as a marker for fecal contamination. A 100 ms detector time constant offers "instantaneous" detection. Pheophorbide detection limits are as low as 10-10 M;These investigations illustrate the utility and importance of the laser in biophysical and analytical chemistry. The experimental information obtained would otherwise be almost impossible to obtain using more conventional light sources.</p>
dc.format.mimetype application/pdf
dc.identifier archive/lib.dr.iastate.edu/rtd/12672/
dc.identifier.articleid 13671
dc.identifier.contextkey 6820686
dc.identifier.doi https://doi.org/10.31274/rtd-180813-13936
dc.identifier.s3bucket isulib-bepress-aws-west
dc.identifier.submissionpath rtd/12672
dc.identifier.uri https://dr.lib.iastate.edu/handle/20.500.12876/66066
dc.language.iso en
dc.source.bitstream archive/lib.dr.iastate.edu/rtd/12672/r_9977311.pdf|||Fri Jan 14 19:27:08 UTC 2022
dc.subject.disciplines Analytical Chemistry
dc.subject.keywords Chemistry
dc.subject.keywords Analytical chemistry
dc.title The laser in biophysical and analytical chemistry: Investigating biophysical processes and dynamics, as well as analytical techniques, as applied to systems of biological and chemical relevance
dc.type article
dc.type.genre dissertation
dspace.entity.type Publication
relation.isOrgUnitOfPublication 42864f6e-7a3d-4be3-8b5a-0ae3c3830a11
thesis.degree.level dissertation
thesis.degree.name Doctor of Philosophy
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