Blue polydiacetylene (PDA) vesicles were prepared and their response to pH changes was investigated using UV-Vis absorption. The effect of the H+ and OH- presence on the size of vesicles was also studied using the dynamic light scattering (DLS) technique. The exposure conditions of pH higher than 9.0 at a temperature of 21 ± 2 °C change the vesicles color from blue to red. Exposure to pH values below 4.0 led to the vesicle’s formation of clusters and precipitation. In initial size analysis, the apparent hydrodynamic diameter of the vesicles was 272 nm (pH 5.0). After titration with HCl and NaOH, sizes decrease from 592 nm to 303 nm increasing the pH from 2.0 to 9.0 and it increases again to 324 nm in pH 9.5. This change in the vesicles’ size can be explained by the changes in the charges of the carboxyl group present in the polydiacetylene that forms them. Changes in polydiacetylene charges and changes in the content of the vesicles studied due to change in pH explain their instability at pH values below 4.0 and the color change from blue to red, for pH above 9.0.
Citation: de Oliveira CP, de Fátima Ferreira Soares N, de Carvalho Teixeira AVN, de Oliveira TV, Filho AMM. 2019. Biomimetic System Characterization: pH-Induced Chromatic Transition and Nanostructural Transformation of Polydiacetyle and Dimyristoylphosphatidylcholine Vesicles Under pH Variation Using Dynamic Light Scattering (DLS) Technique. J Food Chem Nanotechnol 5(3): 65-69.