Figure 4.

(A) Absorbance at λ = 350 nm vs. time for dopamine solutions placed in oxidizing conditions (in the presence of O₂ from the air and at pH = 8.5, 50 mM Tris buffer) in the absence of HSA () and in the presence of HAS at various concentrations: 0.2 mg.mL⁻¹ (), 1 mg.mL⁻¹ (), and 2 mg.mL⁻¹ (). The horizontal dashed line corresponds to the saturation absorption at the end of the oxidation kinetics of dopamine. (B) Hydrodynamic diameter of PDA particles synthesized for 24 h from a 2 mg.mL⁻¹ dopamine solution (50 mM Tris buffer at pH = 8.5) in the presence of HSA at different concentrations (). Hydrodynamic diameter of PDA particles prepared in the same conditions as previously described and stored in a closed bottle (without refreshed air) for 3 months before characterization by dynamic light scattering (). Reproduced from Chassepot and Ball (2014) with authorization.