Many natural biological systems - such as biofilms, shells and skeletal tissues - are able to assemble multifunctional and environmentally responsive multiscale assemblies of living and non-living components. Here, by using inducible genetic circuits and cellular communication circuits to regulate Escherichia coli curli amyloid production, we show that E. coli cells can organize self-assembling amyloid fibrils across multiple length scales, producing amyloid-based materials that are either externally controllable or undergo autonomous patterning. We also interfaced curli fibrils with inorganic materials, such as gold nanoparticles (AuNPs) and quantum dots (QDs), and used these capabilities to create an environmentally responsive biofilm-based electrical switch, produce gold nanowires and nanorods, co-localize AuNPs with CdTe/CdS QDs to modulate QD fluorescence lifetimes, and nucleate the formation of fluorescent ZnS QDs. This work lays a foundation for synthesizing, patterning, and controlling functional composite materials with engineered cells.

Many natural biological systems -such as biofilms, shells and skeletal tissues -are able to assemble multifunctional and environmentally responsive multiscale assemblies of living and nonliving components. Here, by using inducible genetic circuits and cellular communication circuits to regulate Escherichia coli curli amyloid production, we show that E. coli cells can organize selfassembling amyloid fibrils across multiple length scales, producing amyloid-based materials that are either externally controllable or undergo autonomous patterning. We also interfaced curli fibrils with inorganic materials, such as gold nanoparticles (AuNPs) and quantum dots (QDs), and used these capabilities to create an environmentally responsive biofilm-based electrical switch, produce gold nanowires and nanorods, co-localize AuNPs with CdTe/CdS QDs to modulate QD fluorescence lifetimes, and nucleate the formation of fluorescent ZnS QDs. This work lays a foundation for synthesizing, patterning, and controlling functional composite materials with engineered cells.Users may view, print, copy, and download text and data-mine the content in such documents, for the purposes of academic research, subject always to the full Conditions of use:http://www.nature.com/authors/editorial_policies/license.html#terms Additional information Supplementary information is available in the online version of the paper. Reprints and permissions information is available online at www.nature.com/reprints. Correspondence and requests for materials should be addressed to T.K.L. Competing financial interests HHS Public AccessAuthor manuscript Nat Mater. Author manuscript; available in PMC 2014 November 01. Published in final edited form as:Nat Mater. 2014 May ; 13(5): 515-523. doi:10.1038/nmat3912. Author Manuscript Author ManuscriptAuthor Manuscript Author ManuscriptNatural multicellular assemblies such as biofilms, shells, and skeletal tissues have distinctive characteristics that would be useful for materials production and patterning 1-9 . They can detect external signals and respond via remodelling, implement patterning across different length scales, and organize inorganic compounds to create organic-inorganic composites. In this work, such systems provide inspiration for the design of environmentally responsive systems that can integrate biotic and abiotic materials via hierarchical self-assembly. To achieve these capabilities, we engineered artificial gene circuits and self-assembling amyloid fibrils together with synthetic cellular consortia 10-16 and abiotic materials.Our model system is curli, an extracellular amyloid material produced by E. coli that forms fibrils based on the self-assembly of the secreted major curli subunit CsgA 17 . Secreted CsgA monomers are templated on CsgB, which is anchored to the cell surface, to form curli fibrils; moreover, CsgA secreted from one cell can interact with CsgB on other cells 17 . Using synthetic riboregulators 18 , we implemented inducible transcriptional and translational control over the expressi...

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