FIG 4.

Au-conjugated chlorhexidine nanoparticles and chlorhexidine alone exhibited amoebistatic effects. Briefly, A. castellanii (5 × 10⁵ amoebae) organisms were incubated with various concentrations of Au-conjugated chlorhexidine nanoparticles and chlorhexidine alone for 48 h at 37°C as described in Materials and Methods. The next day, amoeba counts were determined by hemocytometer counting. Note that Au-conjugated chlorhexidine nanoparticles at 5 μM concentration, but not chlorhexidine alone at 5 μM concentration, exhibited significant inhibitory effects on A. castellanii growth compared to that of amoebae incubated in solvent alone (P < 0.05 using 2-sample t test with two-tailed distribution). The dotted bar indicates the original inoculum. The results are expressed as the means ± standard errors from three independent experiments performed in duplicate.