Fig. 1. Measuring drug dosage and intracellular accumulation in individual bacteria. A) Schematic of the microfluidic chip used for the ofloxacin accumulation experiment. A main channel of height 25 μm and width 100 μm is used for continuously exchanging the microenvironment with nutrient, drug or dye delivery; cells are confined single-file in a network of side channels whose height and width are close to the cell size. B) Sequence of epifluorescence images (λex = 365 nm) showing the delivery of ofloxacin (12.5 μg ml–1 in PBS; black rectangle) and its corresponding accumulation by the cells in the side channels; a representative individual cell is marked by a red rectangle as a guide. Scale bar = 5 μm.
