Electrokinetically Driven Microfluidics Modules: Towards Patterned Evolution of Tissues

The ability to control and direct patterned evolution of tissues into a fully functional organ from isolated stem cells in vitro has been a long-lasting dream for the scientific community. Once fully realized, it will be a next generation experimental platform for applications ranging from drug discovery & development, cell therapy, whole organ transplant and fundamental biology studies on interorgan and intercellular signaling driving tissue growth/ regeneration and metabolic/immuno-system dynamics. Moreover, it should replace time consuming, inefficient, and expensive animal-based drug screening methods which fails to accurately predict drug response in humans. Therefore, motivated by these exciting opportunities, cutting edge research is being actively pursued to realize the dream and has resulted in several miniaturized organ-on-achip (OOC) as well as multi OOC devices. However, despite the exponential growth in this cutting-edge research area, the field is still in its infancy. Some key challenges need to be overcome before their transition from academic labs to widescale commercial applications. These miniaturized OOC platforms must closely mimic the cellular microenvironment with required chemical/ mechanical/ electrical stimuli, proper extracellular matrix, the correct growth factor protocol to determine stem-cell fate. Furthermore, the platform should allow feedback control with biosensors for signaling proteins released by the cells and molecular/chemical/mechanical/electrical actuators to stimulate and guide the cells. In this thesis, we attempt to address these challenges through the development of multiple electrokinetically driven microfluidics modules which can be integrated to form a semi-automatic OOC system with fast and sensitive protein/DNA biosensors acting as a feedback loop. In Chapter 1, I will review the key literature as well as introduce some concepts used throughout the texts. In Chapter 2, I will present a novel microfluidics-based hearton-a-chip platform where the ion-depletion action of an ion-selective membrane is used to electrically insulate a cell colony. Our unique design elevates the cell medium potential uniformly to synchronously activate and deactivate the voltage-gated ion channels of all cells. In Chapter 3, I will present a technology where the tip streaming mode in an AC electrospray is utilized to encapsulate a single cell in a micron sized hydrogel (both natural and synthetic) at high throughput (~0.1 kHz). The encapsulated stem cells maintained good cell viability over an extended culture period and exhibit robust differentiation potential. In Chapter 4, I will present a bias-free high-throughput and highyield continuous isoelectric fractionation (CIF) nanocarrier fractionation technology to purify protein nanocarriers (EVs, lipoproteins and ribonucleoproteins) and dispersed proteins in cell media (or blood) based on their distinct isoelectric points. In Chapter 5, I present a highly sensitive digital sensor for quantification of proteins at concentration as low as 100 aM. In the last chapter, future directions are provided for each technology as well as some suggestions are made for their integration.