Additive Manufacturing of Engineered Living Materials with Bio‐Augmented Mechanical Properties and Resistance to Degradation

Abstract

Engineered living materials (ELMs) combine living cells with polymeric matrices to yield unique materials with programmable functions. While the cellular platform and the polymer network determine the material properties and applications, there are still gaps in the ability to seamlessly integrate the biotic (cellular) and abiotic (polymer) components into singular materials, then assemble them into devices and machines. Herein, the additive-manufacturing of ELMs wherein bioproduction of metabolites from the encapsulated cells enhanced the properties of the surrounding matrix is demonstrated. First, aqueous resins are developed comprising bovine serum albumin (BSA) and poly(ethylene glycol diacrylate) (PEGDA) with engineered microbes for vat photopolymerization to create objects with a wide array of 3D form factors. The BSA-PEGDA matrix afforded hydrogels that are mechanically stiff and tough for use in load-bearing applications. Second, the continuous in situ production of l-DOPA, naringenin, and betaxanthins from the engineered cells encapsulated within the BSA-PEGDA matrix is demonstrated. These microbial metabolites bioaugmented the properties of the BSA-PEGDA matrix by enhancing the stiffness (l-DOPA) or resistance to enzymatic degradation (betaxanthin). Finally, the assembly of the 3D printed ELM components into mechanically functional bolts and gears to showcase the potential to create functional ELMs for synthetic living machines is demonstrated.

3D Bioprinting of Microbial-based Living Materials for Advanced Energy and Environmental Applications

“…Over the past decade, with the continuous advancement of additive manufacturing technologies, numerous 3D printing techniques suitable for active material fabrication have been developed. 6,15−18 There are primarily three types of 3D bioprinting techniques: jetting-based bioprinting (JBB), 19,20 extrusionbased bioprinting (EBB), 21 and vat polymerization (VP)based bioprinting(VPBB) 22 (Figure 1).…”

Engineered Living Material Bioreactors with Tunable Mechanical Properties using Vat Photopolymerization

“…Previous investigations on ELM have established that different species of microorganisms are viable in hydrogel matrices after photocuring. [9,10,18,28] However, these organisms have not been investigated for their viability in resins for vat photopolymerization. We 3D printed ELMs on a commercial Form 2 printer using an aqueous resin comprising PEGDA-glycerol, photo initiating system, and S. cerevisiae.…”

“…Additive manufacturing is a powerful strategy to fabricate 3D printed ELM with arbitrary designs and form factors. [ 1,9,10 ] The most important considerations for selecting the appropriate polymer matrix are the biocompatibility toward the encapsulated cells and the viscoelastic properties of the material to be 3D printed. We previously reported F127‐based hydrogels for microbial encapsulation and extrusion 3D printing into ELM bioreactors.…”

“…A BSA‐based resin was also reported for the vat photopolymerization with Escherichia coli or Saccharomyces cerevisiae to create bioaugmented ELM. [ 9 ] Both of these approaches use a biopolymer for the polymer matrix, which can be susceptible to biofouling and enzymatic degradation that can potentially affect the long‐term production of bioreactors.…”

Mismatched Refractive Index Strategy for Fabricating Laser‐Driven Wood Diffusers from Bulk Wood for Illumination Applications

“…Poly(ethylene glycol) diacrylate (PEGDA) is a biocompatible and transparent polymer that is widely used in engineered living materials and drug delivery. [41,42] The refractive index of PEGDA is 1.43, which is lower than that of cellulose (1.53), thereby making it suitable for combination with mismatchedrefractive-index polymers. Owing to its unique structure, the laser-driven wood diffuser provides uniform white light with a high coefficient of illuminance variation (CIV) of 17.7% and remains undamaged at a high green laser power of 7.9 J cm −2 .…”