Hydrophilic and antimicrobial Ag-exchanged zeolite a coatings: A year-long durability study and preliminary evidence for their general microbiocidal efficacy to bacteria, fungus and yeast

Silver exchanged zeolite A (Ag–ZA) coatings have been proposed as effective materials in providing hydrophilic and antimicrobial surface properties for condensing heat exchangers onboard manned spacecraft. Ag–ZA coatings demonstrated super hydrophilic properties, retention of silver content, and high antimicrobial activity to Escherichia Coli after submersion in double de-ionized water over a one-year period. Ag–ZA coatings kill E.coli on contact with a small loss of Ag (∼0.4%) after each exposure to the bacterium. The coatings remain super hydrophilic even after 24 repeated E.coli exposures. The coatings have also shown effective resistance against bacteria Listeria innocua, Staphylococcus epidermidis and Pseudomonas putida, Fungus Aureobasidium pullulans, and marine yeast Rhodotorula mucilaginosa, and may provide an enhanced capacity to prevent outbreaks of several microbial species onboard manned spacecraft.

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► The durability of zeolite coatings is examined for the first time for the period of one year.
► The 1 yr test does not degrade coating hydrophilicity, Ag content, and antimicrobial efficacy.
► The coating loses Ag only upon bacteria exposure, but at a very slow rate.
► Zeolite coatings are shown for the first time to be effective against fungi and yeast.