UCLA

Due to the heterogeneity of cellular populations it is important to assay individual cells to garner an accurate representation of the system of interest, and oftentimes the cells which are most critical to detect are in a minority. High-throughput single-cell analysis methods, especially flow cytometry, possess this ability and have had a significant impact on the way many diseases are diagnosed and monitored and the way research in biology is performed. The frontiers of single-cell analysis lie in extending the accessibility of these methods to the point-of-care, where the cell manipulation strategies of traditional flow cytometry are ill-suited, and expanding upon the number and type of biomarkers which can be measured. This dissertation reports the development of new strategies for manipulating cells and particles in high-speed flows, a critical step toward meeting the needs of next-generation cytometric technologies. These strategies employ inertial phenomena present in finite Reynolds number confined flows to transfer cells and particles across laminar streamlines and perform operations on cells. Specifically, this dissertation reports the development of (1) a theoretical background and design criteria for inertial focusing at high Reynolds number, (2) a method for performing continuous rapid solution exchange around cells, and (3) a tool for assaying the mechanical properties of cells at a throughput comparable to flow cytometry (`deformability cytometry'). Generalized design rules, developed in the earlier work, were employed to develop tools for automated cellular sample preparation (`rapid inertial solution exchange') and to focus cells to ensure uniform hydrodynamic stretching in the deformability cytometry method and will be applicable to many future applications of inertial focusing for cytometry, imaging, and bead-based tools. Rapid inertial solution exchange will increase the accessibility of complicated assays to the point-of-care by increasing repeatability of cell-based protocols and minimizing labor-associated time and cost requirements while the label-free metrics provided by deformability cytometry stand in contrast to the variability and cost associated with label-based methods, and potentially extend the use of cytometric methods to new arenas and for more frequent and accurate monitoring of disease.