A. James Clark School of Engineering
Permanent URI for this communityhttp://hdl.handle.net/1903/1654
The collections in this community comprise faculty research works, as well as graduate theses and dissertations.
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Item HIGH THROUGHPUT STIMULATED BRILLOUIN SCATTERING SPECTROSCOPY(2024) Rosvold, Jake Robert; Scarcelli, Giuliano; Bioengineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Brillouin light scattering arises from the coupled interaction between light and material acoustic phonons. The measurand of Brillouin scattering is the characteristic frequency difference between incident and scattered light which depends on the local longitudinal modulus of the material. Spontaneous Brillouin scattering has been used in combination with confocal microscopy to provide non-contact, label-free mapping at micron-scale resolution in biological media. To date, spontaneous Brillouin microscopy has reached the speed limit (~20-50ms per spectrum) as determined by the theoretical scattering efficiency. While a great deal of research has been directed to speeding up Brillouin microscopy acquisition times, spontaneous Brillouin scattering is fundamentally an inefficient process thus limiting the ability to study faster biological phenomena and rapid processes. To combat this limitation, its nonlinear counterpart, stimulated Brillouin scattering (SBS) has been proposed for microscopy applications. For decades, stimulated Brillouin scattering has been used in fiber sensing and all-optical pulse control and leverages a nonlinear interaction where two counterpropagating light beams stimulate a more efficient scattering relationship. However, the small interaction volumes and photodamage constraints presented in microscopy have hindered the translation of stimulated Brillouin scattering into the biological realm. Recently, continuous wave stimulated Brillouin microscopy has led to competitive acquisition times (~5ms per spectrum) when compared to the spontaneous alternative but has yet to be widely adopted. Due to a plethora of factors, such as an inefficient power balance between pump and probe beams, lack of proper commercial laser sources, and nonoptimal detection schemes, the complete picture of what SBS spectroscopy has to offer has yet to be revealed. As such, there is a need to customize light sources and detection schemes in order to fully take advantage of the enhanced Brillouin efficiency possible in SBS. Herein we introduce novel methodology to improve the acquisition speed of Brillouin microscopy by designing and developing proper laser sources and detection schemes for efficient SBS spectroscopy. First, we showcase the potential utility of our state-of-the-art continuous wave SBS technology in a flow cytometry application, highly suitable for the counterpropagating geometry of SBS where the laser position is fixed while the sample is being moved at high speeds. Additionally, we will present an optimized receiver design based on polarization detection which enables 100x faster spectral measurements in the low-gain regime relevant to biological materials. Finally, we demonstrate an optimal pulsed laser source specifically designed for SBS Brillouin microscopy.Item Functionalized Nanoparticles for the Controlled Modulation of Cellular Behavior(2023) Pendragon, Katherine Evelyn; Fisher, John; Delehanty, James; Bioengineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The ability to control cellular behavior at the single-cell level is of great importance for gaining a nuanced understanding of cellular machinery. This dissertation focuses on the development of novel hard nanoparticle (NP) bioconjugate materials, specifically gold nanoparticles (AuNPs) and quantum dots (QDs), for the controlled modulation of cellular behavior. These hard NPs offer advantages such as small size on the order of 1 – 100 nm, high stability, unique optical properties, and the ability to load cargo on a large surface area to volume ratio, making them ideal tools for understanding and controlling cell behavior. In Aim 1, we demonstrate the use of AuNPs to manipulate cellular biological functions, specifically the modulation of membrane potential. We present the conception of anisotropic-shaped AuNPs, known as gold nanoflowers (AuNFs), which exhibit broad absorption extending into the near-infrared region of the spectrum. We demonstrate the effectiveness of utilizing the plasmonic properties AuNFs for inducing plasma membrane depolarization in rat adrenal medulla pheochromocytoma (PC-12) neuron-like cells. Importantly, this is achieved with temporal control and without negatively impacting cellular viability. Aim 2 explores the use of QDs as an optical, trackable scaffold for the multivalent display of growth factors, specifically erythropoietin (EPO), for the enhanced induction of protein expression of aquaporin-4 (AQPN-4) within human astrocytes. This results in enhanced cellular water transport within human astrocytes, a critical function in the brain's glymphatic system. We show that EPO-QD-induced augmented AQPN-4 expression does not negatively impact astrocyte viability and augments the rate of water efflux from astrocytes by approximately two-fold compared to cells treated with monomeric EPO, demonstrating the potential of EPO-NP conjugates as research tools and prospective therapeutics for modulating glymphatic system function. Overall, the body of work presented in this dissertation develops new NP tools, namely solid anisotropic AuNFs and growth factor-delivering QDs, for the understanding and control of cell function. These new functional nanomaterials pave the way for the continued development of novel NP-based tools for the precise modulation of cellular physiology.