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. 2018 Aug 17;6:109. doi: 10.3389/fbioe.2018.00109

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Copyright © 2018 Ball.

This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

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(A) Evolution of the hydrodynamic diameter of PDA aggregates as a function of the surfactant concentration in the case of SDS (), HTAB (), and Triton X-100 (). The dopamine concentration was 2 mg.mL⁻¹ in the presence of 50 mM Tris buffer at pH = 8.5 in all experiments. The long-dashed lines in the upper part of the figure correspond to the size of the PDA prepared in the absence of surfactant, whereas the short-dashed lines in the lower part of the figure corresponds to the size of the surfactant micelles [measured in the case of SDS () and HTAB ()]. (B) Relative deposition of PDA films as calculated by dividing the thickness of the PDA films, obtained on silicon in the presence of a surfactant, by the film thickness obtained in the absence of a surfactant. The film thickness was obtained by means of single wavelength ellipsometry fixing the complex refractive index of PDA to 1.73 ± 0.02i at λ = 632.8 nm. The deposition of PDA on silicon was investigated in the presence of different concentrations of SDS (^______), HTAB (), sodium octylsulfate (), and Triton X-100 (). The error bars are calculated from the standard errors on the film thickness produced both in the absence and presence of surfactants. The long-dashed line has the same significance as in (A). Reproduced from Ponzio et al. (2014a) with authorization.

Inline graphic — (A) Evolution of the hydrodynamic diameter of PDA aggregates as a function of the surfactant concentration in the case of SDS (), HTAB (), and Triton X-100 (). The dopamine concentration was 2 mg.mL⁻¹ in the presence of 50 mM Tris buffer at pH = 8.5 in all experiments. The long-dashed lines in the upper part of the figure correspond to the size of the PDA prepared in the absence of surfactant, whereas the short-dashed lines in the lower part of the figure corresponds to the size of the surfactant micelles [measured in the case of SDS () and HTAB ()]. (B) Relative deposition of PDA films as calculated by dividing the thickness of the PDA films, obtained on silicon in the presence of a surfactant, by the film thickness obtained in the absence of a surfactant. The film thickness was obtained by means of single wavelength ellipsometry fixing the complex refractive index of PDA to 1.73 ± 0.02i at λ = 632.8 nm. The deposition of PDA on silicon was investigated in the presence of different concentrations of SDS (^______), HTAB (), sodium octylsulfate (), and Triton X-100 (). The error bars are calculated from the standard errors on the film thickness produced both in the absence and presence of surfactants. The long-dashed line has the same significance as in (A). Reproduced from Ponzio et al. (2014a) with authorization.