3D Bioprinting of Engineered Living Materials

Engineered Living Materials (ELMs) are rapidly emerging as an exciting new class of functional materials. At the intersection of synthetic biology and materials science, these systems can take advantage of the broad range of modalities now readily achievable with modern genetic engineering, including responsivity, adaptability, growth, and self-healing.¹ Moreover, when coupled with advanced fabrication approaches such as 3D bioprinting, it is possible to generate precise spatial localization of multiple engineered cell populations within robust, handleable structures.²<br/>The degradation of organophosphorus compounds (OPCs) is one challenge that could benefit from ELM development. OPCs are a class of organic molecule that act as acetylcholinesterase inhibitors; their toxicity varies widely, from pesticides such as parathion to chemical warfare agents including sarin and VX. Bioremediation presents an excellent method for soft, sustainable decontamination of OPCs that, along with being applicable directly for patient decontamination or protection, may address the issues of dealing with the presence of persistent hydrophobic nerve agents. Effective containment of engineered cells within an ELM, preventing cell release or DNA transfer to the environment, would enable environmental application.^3,4<br/>Accordingly, we have 3D bioprinted a microporous alginate ELM laden with <i>E. coli</i> expressing the phosphotriesterase (PTE) that hydrolyses OPCs. The material’s 3D printability enabled benchmarking of the kinetic performance of the ELM for OP degradation, along with the behaviour of the living microcolonies contained within the structures. Utilizing the 3D geometries afforded by extrusion printing this living material was incorporated into a flow reactor system whose OPC-degrading performance could be tuned through both the design of flow dynamics and by alteration of proliferation and enzyme expression.<br/><b>References</b><br/>1) Gilbert, C. & Ellis, T. Biological Engineered Living Materials: Growing Functional Materials with Genetically Programmable Properties. <i>ACS Synth. Biol. </i><b>8,</b> 1–15 (2019).<br/>2) Saygili, E., Dogan-Gurbuz, A. A., Yesil-Celiktas, O. & Draz, M. S. 3D bioprinting: A powerful tool to leverage tissue engineering and microbial systems. <i>Bioprinting</i> <b>18, </b>(2020).<br/>3) Mukherjee, S. & Gupta, R. D. Organophosphorus Nerve Agents: Types, Toxicity, and Treatments. <i>J. Toxicol</i>. (2020).<br/>4) Thakur, M., Medintz, I. L. & Walper, S. A. Enzymatic Bioremediation of Organophosphate Compounds—Progress and Remaining Challenges. <i>Front. Bioeng.</i> <b>7,</b> 289 (2019).