Fig 7. Effect of AgNP on the viability of M.tb.

Ten μl of M.tb stock suspension (10⁷ CFU/mL) was diluted to 1 mL with cell culture media (RPMI1640 + 10% PHS, reflecting the environment in which AgNP and M.tb interacted with the MDM in vitro) and incubated at 37°C on a rotating shaker in the presence of 0, 10 and 25 μg/mL of AgNP and 15.7 and 39.25 μg/mL of AgNO₃. The amounts of AgNO₃ corresponded to the amount of Ag⁺ ions present in 10 and 25 μg/mL of AgNP, respectively. M.tb culture samples (10 μL) were removed at 24 hours, diluted 10-fold by serial dilution, plated in triplicate onto 7H10 agar plates and incubated for 21 days at 37°C. CFU were determined as described in the Materials and Methods and plotted as a function of AgNP or Ag⁺ ion concentration. Mean values from two independent experiments ± SD are shown.