Optical advances have had a profound impact on biology and medicine. The capabilities range from sensing biological analytes to whole animal and subcellular imaging and clinical therapies. The work presented in this thesis describes three independent and multifunctional optical systems, which explore clinical therapy at the tissue level, biological structure at the cell/organelle level, and the function of underlying fundamental cellular processes.
First, we present a portable clinical instrument for delivering δ-aminolevulinic acid photodynamic therapy (ALA-PDT) while performing noninvasive spectroscopic monitoring in vivo. Using an off-surface probe, the instrument delivered the treatment beam to a user-defined field on the skin and performed reflectance and fluorescence spectroscopies at two regions within this field. The instrument was used to monitor photosensitizer fluorescence photobleaching, fluorescent photoproduct kinetics, and blood oxygen saturation during a clinical ALA-PDT trial on superficial basal cell carcinoma (sBCC). Protoporphyrin IX and photoproduct fluorescence excited by the 632.8 nm PDT treatment laser was collected between 665 and 775 nm. During a series of brief treatment interruptions at programmable time points, white-light reflectance spectra between 475 and 775 nm were acquired. Fluorescence spectra were corrected for the effects of absorption and scattering, informed by the reflectance measurements, and then decomposed into known fluorophore contributions in real time using a robust singular-value decomposition fitting routine. Reflectance spectra additionally provided information on hemoglobin oxygen saturation.
We next describe the incorporation of this instrument into clinical trials at Roswell Park Cancer Institute (Buffalo, NY). In this trial we examined the effects of light irradiance on photodynamic efficiency and pain. The rate of singlet-oxygen production depends on the product of irradiance and photosensitizer and oxygen concentrations. High irradiance and/or photosensitizer levels cause inefficient treatment from oxygen depletion in preclinical models. This trial established the irradiance-dependence of patient tolerability to ALA-PDT of sBCC and a pain-threshold irradiance, below which patients did not experience significant pain or require anesthetic. The irradiance-dependence of sensitizer photobleaching was also used to determine an optimal irradiance that maximized treatment efficiency. The optimal fluence at a single low irradiance is yet to be determined.
We additionally report the design, construction, and initial characterization of two optical systems used for cellular scattering measurements: a forward scattering white-light spectroscopy system used to characterize lysosomal refractive index and a multifunctional scattering and fluorescence microscope that exploited an angle-resolved forward-scattering geometry. The multifunctional scattering and fluorescence microscope employed brightfield, Fourier-filtered darkfield, direct imaging of the Fourier plane, angle-resolved scattering, and white-light scattering spectroscopy while preserving a fluorescence imaging channel.
Lastly, we report on the development of a microscope-based system used for high-powered, focal laser photolysis. This system was used with cell-permeable caged messenger molecules and analyte specific fluorophores to provide local stimulation of intact cells and subsequent analyte monitoring. This provided a high-precision, non-invasive means for studying Ca2+ dynamics between cell types and between sub-cellular regions within a single cell type. The resulting studies compared the mechanisms underlying the Ca2+ signal globalization in these individual exocrine cell types and under regional messenger release.
|Advisor:||Foster, Thomas H.|
|School:||University of Rochester|
|School Location:||United States -- New York|
|Source:||DAI-B 70/01, Dissertation Abstracts International|
|Subjects:||Biomedical engineering, Optics|
|Keywords:||Biomedical optics, Medical optics, Microscopy, Photodynamic therapy, Scattering, Spectroscopy|
Copyright in each Dissertation and Thesis is retained by the author. All Rights Reserved
The supplemental file or files you are about to download were provided to ProQuest by the author as part of a
dissertation or thesis. The supplemental files are provided "AS IS" without warranty. ProQuest is not responsible for the
content, format or impact on the supplemental file(s) on our system. in some cases, the file type may be unknown or
may be a .exe file. We recommend caution as you open such files.
Copyright of the original materials contained in the supplemental file is retained by the author and your access to the
supplemental files is subject to the ProQuest Terms and Conditions of use.
Depending on the size of the file(s) you are downloading, the system may take some time to download them. Please be