Additive Manufacturing for Recapitulating Biology in vitro and Establishing Cellular & Molecular Communication

Abstract

Recapitulating biological systems within laboratory devices, particularly those with analytical instrumentation, has enhanced our ability to understand biology. Especially useful are systems that provide data at the length and time scales characteristic of the assembled biological systems. In this dissertation, we have employed two advanced technologies — additive manufacturing and electrobiofabrication to create systems that both recapitulate biology and provide ready access to molecular data. First, we utilized two-photon direct laser writing (DLW) and digital light processing (DLP) 3D printing to reconstruct morphologies of human gut villi. Our constructs enable small molecule diffusion through pores and enable epithelial cell growth and differentiation, as in the gastrointestinal (GI) tract. We also developed a cell/particle alignment methodology that applies a vacuum on the underside of a device to rapidly facilitate attachment to 3D printed scaffolds. These simple demonstrations of additive manufacturing show how one can better tailor geometric features of organ-on-a-chip and other in vitro models. We then added electrobiofabrication as a means create functionalized surfaces that rapidly assemble biological components, noted for their labile nature, onto devices with just an applied voltage. In one example, we show how a thiolated polyethylene glycol (PEG) can be electroassembled as a sensor interface that includes antibody binding proteins for both titer and glycan analysis. Rapid assessment of titer and glycan structure is important for biopharmaceuticals development and manufacture. While the interface and sensing methodology was performed using standard laboratory instrumentation, we show that the methodology can be streamlined and operated in parallel by incorporating into a microfluidic sensor platform. Additionally, we show how the combination of optical and electrochemical (redox) based measurements can be combined in a simplified insert that “fits” nearly any microplate reader or other fairly standardized laboratory spectrophotometric unit. We believe that by adapting transformative electrochemical analytical methods so they can augment more traditional optical techniques, we might ultimately generate devices that provide a far more comprehensive picture of the target, promoting better investigation. Specifically, we show how three important biological and chemical systems can be interrogated using both optical measurements and electrochemistry: the oxidation state of proteins including monoclonal antibodies, redox status of hydrogel materials, and electrobiofabrication and electrogenetic induction. Lastly, we demonstrate how electrobiofabrication can be used to create designer communities of bacteria — artificial biofilms — the study of which is important for understanding phenomena from infectious disease to food contamination. That is, we discovered that by varying the applied voltage, surface area, and composition of the to-be-assembled hydrogel solution, we can precisely control the intercellular environment among bacterial populations. In sum, this dissertation integrates advances in assembly, through additive manufacturing, electrobiofabrication, with advances in electrochemical analysis to bring to the fore an electronic understanding of complex biological phenomena. We believe that the capability of translating biological information into a processible digital language opens tremendous opportunities for advancing our understanding of nature’s amazing systems, potentially enabling electronic means to control her subsystems.