Dual action antimicrobial surfaces via combined nitric oxide and silver release

Recent research has demonstrated that silver sulfadiazine and small molecule nitric oxide (NO) donors kill a number of bacterial species synergistically in solution-based assays. Herein, we report on multilayered silica-based xerogels that release both NO and silver. Release of each agent was achieved by exposing amine-modified xerogels to high pressures of NO, and doping silver nitrate (AgNO3) into an alkyl-silane xerogel. Total achievable releases were 3.5 μmol cm(-2) and 1.7 ppm for NO and Ag+, respectively, with release of each agent controlled independent of the other. The NO/Ag+-releasing coating reduced bacterial adhesion and exhibited greater-than-additive killing against both Pseudomonas aeruginosa and Staphylococcus aureus. In contrast, cytotoxicity assays against L929 fibroblasts suggest that the combination does not cause greater-than-additive killing to mammalian cells. Such materials may prove useful in the design of biomedical devices prone to infection such as bone and surgical screws.