<p>  </p> <p>Diabetes, a chronic condition characterized by elevated blood glucose levels, arises when pancreatic β-cells lose capacity to produce a robust, dynamic glucose-stimulated insulin secretion (GSIS) response. Accurate measurement of β-cell health and function <em>ex vivo</em> is thus fundamental to diabetes research, including studies evaluating disease mechanisms, novel drug candidates, and replacement β-cell populations. However, present-day dynamic GSIS assays typically represent end-point measurements, involve expensive commercial perifusion machines, and require time-consuming enzyme-linked immunosorbent assays (ELISA) for insulin detection. Microfluidic devices developed as accessible, low-cost alternatives still rely on secondary ELISAs and suspend islets in liquid medium, limiting their survival <em>in vitro</em>. Here, we present a novel, 3D-printed microphysiological system (MPS) designed to recreate components of <em>in-vivo</em> microenvironments through encapsulation in fibrillar type I collagen and restoration of favorable molecular transport conditions. Following computational-informed design and rapid prototyping, the MPS platform sustained collagen-encapsulated mouse islet viability and cytoarchitecture for 5 days and supported <em>in-situ</em> measurements of dynamic β-cell function. To rapidly detect insulin secretion from β-cells in the MPS, we then developed a highly sensitive electrochemical sensor for zinc (Zn2+), co-released with insulin, based on glassy carbon electrodes modified with bismuth and indium and coated with Nafion. Finally, we validated sensor detection of Zn2+ released from glucose-stimulated INS-1 β-cells and primary mouse islets, finding high correlation with insulin as measured by standard ELISA. Together, the 3D MPS and Zn2+ sensor developed in this dissertation represent novel platforms for evaluating β-cell health and function in a low-cost, user-friendly, and physiologically-relevant manner. </p>

<p dir="ltr">Pancreatic ductal adenocarcinoma (PDAC) remains one of the most deadliest cancer and despite advancements in cancer therapy, remain highly refractory to treatment, largely due to its desmoplastic tumor microenvironment (TME) characterized by complex interactions among cancer cells and stromal components. Particularly, the PDAC associated coagulation system due to leaky tumor vasculatures plays a pivotal role in reshaping the PDAC stroma and its pathogenesis. Understanding the intricate interplay between tumor cells, stromal cells, and the elevated coagulation pathway elements, including tissue factor, thrombin, and fibrin, is essential for developing effective therapeutic strategies. To address these challenges, this research proposes the engineering of a novel PDAC-associated coagulation system using a microfluidic technology, known as coagulation-on-tumor-microenvironment-on-chip (cT-MOC). The study aims to integrate key coagulation pathways in cT-MOC to investigate pivotal interactions in the PDAC stroma: <i>i)</i> thrombin-protease-activated receptors (PARs) mediated promotion of PDAC fibrosis via activation of cancer-fibroblast cross-talk; <i>ii)</i> in-depth analysis of transport and mechanical properties of collagen-fibrin microstructure; <i>iii)</i> inhibited drug delivery in reprogrammed PDAC stroma due to pronounced fibrin deposition on collagen. By leveraging innovative microfluidic technologies and comprehensive experimental approaches, the research endeavors to provide a novel platform that bridges traditional <i>in vitro</i> and <i>in vivo</i> models to overcome the challenges posed by the desmoplastic TME and enhance therapeutic strategies for treatment by targeting the coagulation at the PDAC TME.</p>