Fig. 4.

Release of drug via MIMS. Colony expansion (a–c) and proliferation (d) of P. mirabilis observed 20 h after cells were inoculated on 1% (a–c) and 4% (d) agar. Copolymer 3-coated silica particles were deposited evenly on the left side of the agar surface. 0.8 mg of drug-free particles (a), and 0.2 (b, d) and 0.05 (c) mg of particles containing tobramycin were used. a–c P. mirabilis cells were inoculated on the right side of agar at point x. The vertical dotted line (black) is the boundary between the particle and particle-free zones that divides the agar into two equal halves, and the horizontal dotted line (green) in a bisects it. The blue and red arrows in b and c indicate the intersection points between the horizontal bisector with the secondary and primary colony fronts, respectively. d P. mirabilis were inoculated on the whole agar and immobile P. mirabilis cells were seen to proliferate throughout the agar. Scale bar: 2 cm