Designing surfaces that kill bacteria on contact

Poly(4-vinyl-N-alkylpyridinium bromide) was covalently attached to glass sl ides to create a surface that kills airborne bacteria on contact. The antib acterial properties were assessed by spraying aqueous suspensions of bacter ial cells on the surface, followed by air drying and counting the number of cells remaining viable (i.e., capable of growing colonies). Amino glass sl ides were acylated with acryloyl chloride, copolymerized with 4-vinylpyridi ne, and N-alky]ated with different alkyl bromides (from propyl to hexadecyl ). The resultant surfaces, depending on the alkyl group, were able to kill up to 94 +/- 4% of Staphylococcus aureus cells sprayed on them. A surface a lternatively created by attaching poly(4-vinylpyridine) to a glass slide an d alkylating it with hexyl bromide killed 94 +/- 3% of the deposited S. aur eus cells. On surfaces modified with N-hexylated poly(4-vinyipyridine), the numbers of viable cells of another Gram-positive bacterium, Staphylococcus epidermidis, as well as of the Gram-negative bacteria Pseudomonas aerugino sa and Escherichia coli, dropped more than 100-fold compared with the origi nal amino glass, In contrast, the number of viable bacterial cells did not decline significantly after spraying on such common materials as ceramics, plastics, metals, and wood.