4D Printing of Engineered Living Materials

Abstract

Herein, a method that uses direct-ink-write printing to fabricate engineering living materials (ELMs) that respond by undergoing a programmed shape change in response to specific molecules is reported. Stimuli-responsiveness is imparted to ELMs by integrating genetically engineered yeast that only proliferate in the presence of specific biomolecules. This proliferation, in turn, leads to a shape change in the ELM in response to that biomolecule. These ELMs are fabricated by coprinting bioinks that contain multiple yeast strains. Locally, cellular proliferation leads to controllable shape change of the material resulting in up to a 370% increase in volume. Globally, the printed 3D structures contain regions of material that increase in volume and regions that do not under a given set of conditions, leading to programmable changes in form in response to target amino acids and nucleotides. Finally, this printing method is applied to design a reservoir-based drug delivery system for the on-demand delivery of a model drug in response to a specific biomolecule.

Hydrogels as promising platforms for engineered living bacteria-mediated therapeutic systems

“…First, these macroscopic soft materials can provide sufficient space to accommodate the bacteria even though they have a much larger volume than small molecule drugs [ 26 , 30 ]. Second, the good biocompatibility and tunable physicochemical properties of hydrogels are conducive to maintaining bacterial vitality as well as improving treatment efficacy [ 35 , 36 ]. Third, their adjustable pore structure and mechanical properties provide physical barriers that can not only protect the living bacteria from potential clearance and inactivation but also deliver the bacterial therapeutic agents in a controllable and safe manner [ 13 , 26 , 37 ].…”

Combining printing and nanoparticle assembly: Methodology and application of nanoparticle patterning

“…Materials are mainly divided into categories according to the deformation driving force of the structures, namely, heat (for example, shape memory polymers [SMPs]), 102 light (e.g., photoresponsive polymers), 93 , 103 electric fields (e.g., carbon nanotube), 104 , 105 , 106 magnetic fields (e.g., Fe 3 O 4 and FeO), 107 , 108 and reactants (e.g., polyacrylic acid, poly(n-isopropylacrylamide), and polyvinyl alcohol). 109 , 110 , 111 Although the technology is in its infancy, 4D printed technology combined with NP assembly can serve as an effective method for constructing stimuli-responsive microstructures for reversible and two-way self-assemblies. 112 This section briefly discusses the application and development prospects of nanoassembly and 4D printing under different stimuli, such as thermal, magnetic, and reactants.…”

Digitally Programmable Manufacturing of Living Materials Grown from Biowaste

“…Engineered living materials (ELMs) are composites where living cells are combined with synthetic materials. − The resulting living materials derive functionalities from biological activities while keeping material properties for engineering applications. − One class of ELMs focuses on functionalities directly from the biochemical activities of the living cells, including fungal-based self-cleaning living surfaces that metabolize food spills, 3D-printed bacterial structures as living electrodes, yeast–laden living hydrogels for continuous biofermentation, and encapsulated bacteria as wearable sensors . Another approach in ELMs is to utilize the biochemical activities of living cells to control the mechanical properties of the living materials or produce functional materials. − For example, dried yeast themselves can serve as building blocks of stiff materials, and mycelia can adhere sawdust into solid objects. − Bacteria-assisted mineralization can help self-heal concrete or improve the toughness of 3D-printed polymer scaffolds .…”