Fig. 3.

Schematic layout of the experimental procedure used for the toxicity experiments. Five-millimeter nanoparticle-laden filter discs were cut out of the original filter (step 1) while E. coli cultures were laid on the MH2 agar plates (step 2). The filter discs were then deposited on the E. coli cultures with the nanoparticle deposition side facing down (step 3). The size of the inhibition zones around the filter discs was measured after 48 h of incubation (step 4)