| dc.description.abstract | The biomechanical properties of tissues and their constituent cells are a critical component in determining their function, development, and overall wellness. As such, many approaches have been developed to measure these properties. Atomic force microscopy (AFM), magnetic twisting cytometry (MTC), particle-tracking microrheology (PTM), parallel-plates rheometry, cell monolayer rheology (CMR), and optical stretching (OS) are only some of the methods used to investigate cell and tissue biomechanics. These modern investigative methods are all either invasive and destructive or require the introduction of foreign agents, thereby changing the natural state of the sample. Optical techniques such as optical coherence elastography have shown promise and become more prevalent for tissue-level studies, but still require mechanical excitations and are limited regarding spatial resolution. The few optical techniques available are generally limited to either micro-scale or macro-scale measurements, and are not applicable at both tissue and cellular levels. Advances in spectroscopic methods, however, have provided a viable alternative capable of both micro- and macro-scopic measurements for both tissues and cellular level studies: Brillouin spectroscopy. Brillouin spectroscopy is an all-optical, non-invasive, label-free investigative technique that has rapidly emerged as a powerful tool in biomedical sensing and imaging. The past 15 years have seen an expansive growth in Brillouin spectroscopy utilization and development. The implementation of static dispersion optics, a range of elastic scattering background removal techniques, and improved data analysis methods have helped to bring Brillouin spectroscopy to the forefront of elastography and use in biomedical applications. Recently, Brillouin spectroscopy has also been adapted for use as an imaging modality, enabling mechanical mapping of biological material properties. This dissertation covers the development of a custom built high resolution multi-modal confocal microscopy system and its application to achieve a series of firsts in cellular level studies: the first non-contact recording of subcellular biomechanical changes in response to a non-specific external stimulus, the first reporting of sub-second biomechanical changes using spontaneous Brillouin spectroscopy, and the first reporting of sub-second dynamic biomechanical changes with location specificity in each of the cytoplasm, nucleoplasm, and nucleolar compartments of cells. The custom microscopy system is capable of simultaneous Raman and Brillouin spectroscopic measurements, allowing for measurement of both the chemical and mechanical properties from micro- or macro-level materials. This dissertation also provides details about a unique synergistic behavior between short picosecond optical and nanosecond electrical pulses that was discovered while considering surrogate exposure methods for generating transient pressure waves comparable to those produced by electrodes during nanosecond pulsed electric fields in cell culture exposures. | en |
