Painting and Printing Living Bacteria: Engineering Nanoporous Biocatalytic Coatings to Preserve Microbial Viability and Intensify Reactivity

Authors

  • Michael C. Flickinger,

    Corresponding author
    1. BioTechnology Institute, University of Minnesota, 140 Gortner Laboratories, 1479 Gortner Avenue, St. Paul, Minnesota 55108
    2. Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, 140 Gortner Laboratories, 1479 Gortner Avenue, St. Paul, Minnesota 55108
    • BioTechnology Institute, University of Minnesota, 140 Gortner Laboratories, 1479 Gortner Avenue, St. Paul, Minnesota 55108. Tel: 612 624–9259. Fax: 612 625–1700
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  • Janet L. Schottel,

    1. Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, 140 Gortner Laboratories, 1479 Gortner Avenue, St. Paul, Minnesota 55108
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  • Daniel R. Bond,

    1. BioTechnology Institute, University of Minnesota, 140 Gortner Laboratories, 1479 Gortner Avenue, St. Paul, Minnesota 55108
    2. Department of Microbiology, University of Minnesota, 1460 Mayo, 420 Delaware Street SE, Minneapolis, Minnesota 55455
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  • Alptekin Aksan,

    1. Department of Mechanical Engineering, University of Minnesota, 241 Mechanical Engineering Building, 111 Church Street SE, Minneapolis, Minnesota
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  • L. E. Scriven

    1. Department of Chemical Engineering and Materials Science, University of Minnesota, 151 Amundson Hall, 421 Washington Avenue SE, Minneapolis, Minnesota 55455
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Abstract

Latex biocatalytic coatings containing ∼50% by volume of microorganisms stabilize, concentrate and preserve cell viability on surfaces at ambient temperature. Coatings can be formed on a variety of surfaces, delaminated to generate stand-alone membranes or formulated as reactive inks for piezoelectric deposition of viable microbes. As the latex emulsion dries, cell preservation by partial desiccation occurs simultaneously with the formation of pores and adhesion to the substrate. The result is living cells permanently entrapped, surrounded by nanopores generated by partially coalesced polymer particles. Nanoporosity is essential for preserving microbial viability and coating reactivity. Cryo-SEM methods have been developed to visualize hydrated coating microstructure, confocal microscopy and dispersible coating methods have been developed to quantify the activity of the entrapped cells, and FTIR methods are being developed to determine the structure of vitrified biomolecules within and surrounding the cells in dry coatings. Coating microstructure, stability and reactivity are investigated using small patch or strip coatings where bacteria are concentrated 102- to 103-fold in 5–75 μm thick layers with pores formed by carbohydrate porogens. The carbohydrate porogens also function as osmoprotectants and are postulated to preserve microbial viability by formation of glasses inside the microbes during coat drying; however, the molecular mechanism of cell preservation by latex coatings is not known. Emerging applications include coatings for multistep oxidations, photoreactive coatings, stabilization of hyperthermophiles, environmental biosensors, microbial fuel cells, as reaction zones in microfluidic devices, or as very high intensity (>100 g·L-1 coating volume·h-1) industrial or environmental biocatalysts. We anticipate expanded use of nanoporous adhesive coatings for prokaryotic and eukaryotic cell preservation at ambient temperature and the design of highly reactive “living” paints and inks.

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