Relationship of color change to permeation of target compound in polydiacetylene vesicle system

Abstract

AbstractPolydiacetylene (PDA) systems, which showed color changes due to the permeation of target molecules, were reported previously by our research group. To use the systems for controlled drug delivery systems, the relationship of the color change to the permeation time of the PDA vesicle must be characterized precisely. Therefore, this relationship was investigated and characterized in this study. Methotrexate (MTX) was used as the target compound and the detection of MTX is an important process in anticancer study. N‐(2‐aminoethyl)pentacosa‐10,12‐diynamide (AEPCDA) was used as the diacetylene surfactant. Dimethyldioctadecylammonium bromide (DOAB) was used as an assistant surfactant. The color change occurred when the mixed surfactant vesicles, with DOAB, were used. When a lower ratio of DOAB was added to the AEPCDA vesicle, the color change rate was slower than that when using the higher ratio of DOAB. The color change rate constants were estimated for several different ratios (AEPCDA:DOAB). Surfactants with different carbon numbers to DOAB were used as the assistant surfactants in this study. The results showed that the color change rate constant decreased with the increasing carbon number of the assistant surfactant. This means that the color change rate can be controlled by changing the assistant surfactant.