Fig. 7

Accumulation of NPs and PLL-coated NPs in S. aureus biofilms. a CLSM micrographs of NP-Dy650 and NP-Dy650-PLL (in red) with initial solid contents of 0.0006% and 0.005% in a 20 µm layer thickness (between + 5 and + 25 µm from the plate bottom) of Syto9-stained biofilms (in green) and shortly incubated (45 min) before washing. Ratio of fluorescence intensities of remaining NP-Dy650 and NP-Dy650-PLL, related to Syto9-stained biofilms, quantified from CLSM micrographs (b) and from measurements by spectrofluorimetry in microplate wells (c). Relative adhered biomass of S. aureus biofilms stained by CV, after 45 min exposure of 24 h-old biofilms to RIF, NP-RIF or NP-RIF-PLL with initial solid contents of 0.0006% and RIF concentrations of 0.25 µg/mL (d) or initial solid contents of 0.005% and 2 µg/mL of RIF (e), followed by washing to remove poorly-interacting particles and 24 h incubation. Percentages are reported to the untreated condition. Each picture represents data obtained with three replicates in two independent experiments. Values are means ± SD of three replicates for one representative experiment out of three independent ones. ANOVA, ns: not significant, * p < 0.05, ** p < 0.01 and *** p < 0.001