3D Bioprinted Engineered Living Materials for Continuous Organophosphorus Compound Detoxification

Engineered living materials (ELMs) are a rapidly emerging class of materials, demonstrating a wide range of functionalities, including responsive morphing, self-healing, and bio-catalysis. 3D bioprinted hydrogels have been used for the fabrication of high resolution, compartmentalised, and load-bearing structures suitable for hosting microbial metabolism, and accordingly represent an ideal environment for ELMs. The interactions between material frameworks, such as hydrogels, and encapsulated life are now beginning to be investigated. Herein, by 3D printing a hydrogel-encapsulated population of Escherichia coli, a chemically inducible, metabolically active, microbial ELM was fabricated. The material was characterised using a wide range of techniques, including fluorescence microscopy and cryogenic electron microscopy. Toxic organophosphorus compound (OPC) detoxifying capabilities were conveyed to the material through inducible expression of Agrobacterium radiobacter phosphotriesterase (arPTE). The reaction diffusion process occurring at the interface of the OPC detoxifying ELM was investigated using continuous fluorescence imaging of Coumaphos hydrolysis.. Principal component analysis was then used to uncover spatial and temporal features within this data, with relevance for future optimisation of catalytic microbial ELM structures. To further demonstrate the applicability of this 3D printable microbial ELM, the material was incorporated into an entirely 3D printed flow reactor, demonstrating effective, cyclical detoxification of an OPC solution at high flow rate. Looking towards the future of ELM design, a novel, 3D printable, contractile-thermosensitive, double-network hydrogel was used to create thermo-responsive OPC degrading bioreactors, capable of autonomously controlling their performance.