Paper TF-MoA6
Atomic Layer Deposition of Nano-Coatings on Fabrics for Antibacterial Applications

Monday, October 30, 2017, 3:20 pm, Room 20

About 1.7 million Americans contract hospital-acquired infections every year resulting in 99,000 inadvertent deaths and an estimated $20 billion in healthcare costs. Here, we investigate the use of atomic layer deposition (ALD) to treat various fabrics (e.g., polyester, cotton, and blends) with antimicrobial inorganic materials to create unique antibacterial linens, scrubs, and hospital gowns. Our protocols include biological testing of the antibiotic performance of ALD-treated fabrics against DH5-α, a strain of E. coli that is engineered to be suitable for laboratory purposes. Antibacterial performance is tracked as a function of ALD cycle number at various deposition temperatures. Fabrics were exposed to E. coli and then incubated for 20 hours, after which cultures are serially diluted up to 7 times, spotted onto Petri dishes, and incubated for another 20 hours. Colony counting is then used to quantify antibiotic effectiveness.

For ZnO ALD coatings of 0, 1, 10, and 100 cycles, we find that only the 100 cycle sample is sufficiently cytotoxic to kill all of the E. colibacteria. Interestingly, for only a few cycles of ZnO (1, 3, and 10 cycles) the bacteria appears to grow more rapidly. We attribute this increased bacterial growth rate to the Zn²⁺ ions acting as a nutrient for the bacteria. It is known that in order to be an effective antimicrobial agent, ZnO must be “nano-sized” or larger; atomic forms of Zn and ZnO, which ionize into Zn²⁺ in nutrient broth, act instead as nutrients. A more detailed investigation of this transition from nutrient to antimicrobial will be discussed during this talk. We will also examine the effectiveness of other oxide materials including TiO₂ and ZrO₂ as well as compare the long-term performance of ZnO against common disinfectants like Lysol® and their stability in aqueous environments of varying pH.