Surfactants are widely used by food industry thus its discharge is an environmental concern; and development of Polydiacetylene (PDA)-based sensors may detect these molecules. However, to improve the sensor efficiency is necessary to understand interactions between PDA vesicles and surfactants. In this work, we purpose to investigate the interactions between surfactants and PDA vesicles as well as between surfactants and PDA + cholesterol (CHO) + sphingomyelin (SPH) vesicles dispersed in water. The addition of a cationic surfactant, hexadecyltrimethylammonium bromide (CTAB), induced a blue-tored spectrophotometric transition in both structures; however, the addition of the anionic compounds, sodium dodecyl sulfate (NaDS) and lithium dodecyl sulfate (LiDS) did not change the vesicle color. The addition of the cationic surfactant increased the hydrodynamic radium (Rh) of the PDA vesicles (from 39.82 ± 3 nm to 96.85 ± 3 nm) and the PDA/CHO/SHP vesicles (from 160.89 ± 3 nm to 219.84 ± 3 nm). The presence of NaDS and LiDS also increased the size of the PDA vesicles (to 43.50 ± 3 nm and 43.75 ± 3 nm, respectively) and the PDA/ CHO/SPH vesicles (to 201.91 ± 3 nm and 210.24 ± 3 nm, respectively). The interaction energies between the cationic surfactant and PDA and PDA/CHO/ SPH were different; however, both were entropically driven. PDA vesicles show potential to be used as sensors for cationic surfactants detection.

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