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Significant advances are being made in the incorporation of enzymes into functional materials, which leverage their inherent substrate specificity, efficient catalytic activity, and sustainable origin. These engineered "dead" materials, however, lack the incredible systems‐level control of enzyme activity that living organisms have evolved over millennia. This gap is now being bridged by the rapidly emerging field of engineered living materials (ELMs), which couples the tools of advanced synthetic biology with modern materials science. In this review, the impressive array of methodologies used to fabricate the extensive library of functional enzyme‐based dead materials is discussed, and the design strategies that facilitate their creation unpacked. The spectacular suite of natural and synthetic genetic and post‐translational control systems for enzymes in living organisms is then described. Finally, key recent examples of ELMs that utilize enzyme activity are reviewed, highlighting the central role of the living component in providing responsivity and adaptability to this new class of materials. [ABSTRACT FROM AUTHOR]

The synthesis of a porous shape‐changing interpenetrating network (IPN) bioink for the fabrication of large‐scale (cm) reversibly thermosensitive structures is described. The poly(N‐isopropylacrylamide) (PNIPAm) IPN is generated in situ within an ionically crosslinked alginate hydrogel at room temperature and under aerobic conditions using a horseradish peroxidase (HRP)/glucose oxidase (GOx) bienzymatic initiation system. Mechanical testing assessment of the IPN hydrogels confirm mechanical reinforcement via covalent single network interdigitation. Furthermore, the thermosensitive bioink can be used to print biohybrid reactors containing genetically engineered phosphotriesterase‐expressing E. coli capable of hydrolyzing toxic organophosphorus compounds. Herein, increasing the bioink pore size using the contractile‐thermosensitive response of the IPN improves the temperature‐dependent theoretical mass‐transfer‐limited enzyme catalyzed reaction rate, providing a plausible route to externally regulated enzymatic catalysis within bioprinted structures. [ABSTRACT FROM AUTHOR]