In this thesis, we investigate biological molecules on a micron scale in the ultraviolet spectral region through the non-destructive confocal absorption microscopy. The setup involves a combination of confocal microscope with a UV light excitation beam to measure the optical absorption spectra with spatial resolution of 1.4 μm in the lateral and 3.6 μm in the axial direction. Confocal absorption microscopy has the benefits of requiring no labels and only low light intensity for excitation while providing a strong signal from the contrast generated by the attenuation of propagating light due to absorption. This enables spatially resolved measurements of single live cells and bio-molecules with less than 10^9 molecules in the probe volume. Employing a multichannel detection system, the absorption spectrum of hemoglobin in a single red blood cell is measured on the timescale of seconds. We also extend the spectral range from the visible range to the experimentally more challenging ultra-violet region where characteristic absorption bands of bio-molecules are observed. Exploiting the ultra-violet range, amino acids, nucleic acids solutions, and plant cells are investigated. We measure the spatially resolved absorption spectra at the nucleus of an onion cell and cytoplasm to probe DNA base-pair absorption. Small variations in our micro-absorption data are seen around 260 nm, possibly due to the abundance of DNA in the nucleus. This thesis contributes to the goal of spectroscopic identification of spatial heterogeneities at the single cell level and the label-free detection of proteins and nucleic acids.
Bachelor of Science (B.S.)
College of Medicine
Burnett School of Biomedical Sciences
Orlando (Main) Campus
Length of Campus-only Access
Kera, Jeslin, "Micro-Spectroscopy of Bio-Assemblies at the Single Cell Level" (2017). Honors Undergraduate Theses. 356.
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