Figure 3.

Viability of bacterial strain CFT073 after 24 h (red line) and 96 h (blue line) against reused Ag NPs. Bacteria were cultured at 37°C with shaking at 200 r.p.m. in L broth to mid-logarithmic phase. Of note, 50 µl aliquots of mid-logarithmic cultures (equivalent to approx. 10⁶ cells) were incubated with an equal volume of water in the 96-well plates containing the previously employed nanoparticles at different concentrations (from 0.62 to 100 µg ml⁻¹ final concentration). The same well employed for the previous experiment was used as a negative control while ethanol was added instead of water as a positive control. After 24 and 96 h luminescence was read and the RLUs of untreated samples were normalized to 100% (see Material and methods). (a–d): CFT073. Data are means of three independent determinations ± s.d. Ag Pristine (a), Ag PVP (b), Ag CIT (c) and Ag HEC (d).