FIGURE 6.

Physical characteristics and uptake of microbial particles. A, the zeta potentials of bacterial strains S. aureus, S. pneumoniae, and Yersinia were measured in different ionic strength PBS solutions by dispersing 8 × 10⁷ bacteria/1.5 ml solution. The zeta potential for each bacterial strain was measured in triplicate. Microbial particles show higher magnitude zeta potentials (more negative) than PLGA nanoparticles across the range of ionic strength. B, S. aureus uptake versus ionic strength, showing increased uptake at low ionic strength. C, confocal projection image of NALT showing UEA-1-positive M cells (green) and fluorescently labeled bacteria (red).