Fig 1.
Chemical structures of (A) pheomelanin [44] and (B) EDTA [45].
Fig 2.
Zeta potential of pheomelanin nanoparticles as a function of concentration.
Zeta potential of pheomelanin nanoparticles in different solvents: milli-Q water (blue), PBS (black) and PBS+EDTA (red), at 166 μg/mL.
Fig 3.
Scanning electron microscopy and particle size distribution.
Scanning electron micrograph image of synthesized pheomelanin at 50 k X and the particle size distribution (inset) in PBS (n = 10).
Fig 4.
Toxicity and photoinactivation effect of pheomelanin nanoparticles.
Dark toxicity (circles) and bactericidal effect (triangles) of pheomelanin nanoparticles at different concentrations against E. coli exposed 1 h to blue light. Values represent averages ± standard deviations of three different experiments.
Table 1.
Effect of blue light on E. coli using pheomelanin nanoparticles.
Table 2.
Effect of UVA radiation on E. coli using pheomelanin nanoparticles.
Fig 5.
E. coli photoinactivation with pheomelanin nanoparticles excited with blue light with and without EDTA (10 mM).
The cultures at 166 μg/mL of pheomelanin nanoparticles were irradiated during 3 h (270 J/cm2). Controls are PBS, PS, Blue light and EDTA. The strongest photoinactivation effect is depicted as Blue L+PS+EDTA. Values are averages and standard deviations of three biological triplicate. * p<0.05.
Fig 6.
E. coli photoinactivation with pheomelanin nanoparticles excited with UVA radiation with and without EDTA (10 mM).
The cultures at 166 μg/mL of pheomelanin nanoparticles were irradiated during 3 h (270 J/cm2). Controls are PBS, PS, UVA and EDTA. The strongest photoinactivation effect is depicted as UVA+PS+EDTA. Values are averages and standard deviations of three biological triplicate. * p<0.05.
Fig 7.
(A) Fluorescence generated from SOSG (1.92 μM) and HPF (5 mM) with pheomelanin nanoparticles, at 525 (green diamonds) and 515 nm (blue circles), respectively. Data are normalized to the maximum value in each case: 3.44x106, and 3.42x106 fluorescence units for SOSG and HPF, respectively. The samples were exposed to UVA radiation during 6 hours and evaluated every 2 hours. (B) Power emitted by singlet oxygen during UVA radiation (see section Materials and Methods). The measurements were obtained for 3 minutes. The black line is the average and the band the dispersion of the data from three independent experiments. The large dispersion is due to the detection method.