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Nanoporous coatings to entrap bacteria

Biocatalytic coating for microbial Viability
Researchers of University of Minnesota have developed a nanoporous biocatalytic coating and still preserve microbial viability of entrap bacteria on various surfaces.
Biocatalytic coatings
Coatings are formed on a variety of surfaces, delaminated to generate stand-alone membranes or formulated as reactive inks for piezoelectric deposition of viable microbes. For this purpose latex biocatalytic coatings are used. This coating containing up to 50% by volume of microorganisms can stabilize, concentrate and preserve cell viability on surfaces at ambient temperature. As the latex emulsion dries, cell preservation by partial desiccation occurs simultaneously with the formation of pores and adhesion to the substrate. This results in permanently entrapped living cells, surrounded by nanopores generated by partially coalesced polymer particles. Such a nanoporosity is essential for preserving microbial viability and coating reactivity.
Microstructure of hydrated coating can be visualized using Cryo-SEM methods, confocal microscopy, dispersible coating methods can be used to quantify the activity of the entrapped cells and FTIR methods can be employed to determine the structure of vitrified biomolecules within and surrounding the cells in dry coatings.
Microstructure, stability and reactivity of coating are investigated using small patch or strip coatings having small concentration of bacteria 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 multi step oxidations, photo reactive coatings, stabilization of hyperthermophiles, environmental biosensors, microbial fuel cells, as reaction zones in micro fluidic devices, or as very high intensity industrial or environmental biocatalysts. Further use of nanoporous adhesive coatings for prokaryotic and eukaryotic cell preservation at ambient temperature and the design of highly reactive living paints and inks are possible in the future.
Cells immobilized on graphite paper electrodes
Transfer of electrons by bacteria to conductive surfaces are of interest as catalysts in microbial fuel cells, as well as in bio processing, bioremediation and corrosion. Immobilization of Geobacter sulfurreducens on graphite electrodes can be done to allow routine, repeatable electrochemical analysis of cell-electrode interactions.
Immediately after immobilizing G. sulfurreducens on electrodes, electrical current can be obtained without addition of exogenous electron shuttles or electro active polymers. The ability of washed G. sulfurreducens cells to immediately produce electrical current is consistent with the external surface of this bacterium possessing a pathway linking oxidative metabolism to extra cellular electron transfer. This electrochemical activity of pectin-immobilized bacteria illustrates a strategy for preparation of catalytic electrodes and study of Geobacter under defined conditions.

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