Antibacterial nitric oxide-releasing xerogels: Cell viability and parallel plate flow cell adhesion studies

The ability of nitric oxide (NO)-releasing xerogels to reduce adhesion of Pseudomonas aeruginosa under flowing conditions was evaluated using a parallel plate flow chamber. At a controlled bacterial suspension flow rate of 0.2 mL/min, the NO-releasing xerogels reduced bacterial adhesion in a flux-dependent fashion, with an NO flux of 21 pmol cm−2 s−1 reducing P. aeruginosa adhesion by 65% compared to controls. Fluorescent viability staining indicated that bacteria adhered to NO-releasing xerogels were killed within 7 h. Quantitative cell-plating viability studies showed that the extent of bactericidal activity was dependent on the total amount of NO released, with 750 nmol cm−2 killing >90% more adhered bacteria than xerogels releasing 25 nmol cm−2. Thus, NO-releasing xerogels were shown to both inhibit P. aeruginosa adhesion and kill adhered bacteria cells, two important steps toward designing anti-infective biomaterial coatings.