PhD Dissertation Defense: Joshua Sampson

Title: Optical Enzymatic Bioprinting of Fibrin

Abstract: Fabricated tissues would be groundbreaking for transplantation, pharmaceutical testing, disease modeling, and basic science. But the biological tissues they must aim to mimic contain staggering architectural complexity across many length scales. For example, vascular structures—vital for tissue to be vital—comprise complex networks spanning from ~10 μm capillaries to ~1 cm arteries, a three-order-of-magnitude range. To keep cells alive in fabricated tissue, even engineered ersatz vasculature should place small vessels of approximately the diameter of human hair (100 μm) at a spacing of a similar distance, while connecting them hierarchically to larger vessels to permit perfusion throughout cubic centimeters of tissue.

The ability of light-based 3D printing to pattern intricate features at high density across large areas may well suit it to this challenge. However, the most biologically favorable structural materials that have yielded the most biologically advanced microtissue models—natural extracellular matrix protein such as fibrin and collagen—have not been able to be 3D printed with light.

In this thesis, I first combine light control of thrombin activity via an existing azobenzene/aptamer system with digital light processing (DLP) printing to fabricate wholly natural fibrin structures. Second, I develop novel systems for light-gating thrombin and demonstrate their use.

Please contact Sofia Rakicevic-More for the Zoom link.