Controlled Release from Monoolein Cubic Phase by Complexation Between Acidic Proteinoid and Basic Proteinoid

Acidic proteinoid and basic proteinoid were included in the water channel of the cubic phase to design a pH-sensitive monoolein (MO) cubic phase. Proteinoid composed of Asp and Leu (PAL) and proteinoid of Lys (PL) were prepared by a melt-condensation method and they used as acidic and basic porteinoid, respectively. Maximum complexation between PAL and PL was observed at pH 7.0 and at the PAL/PL ratio of 3/7 (v/v), evidenced by the size and the light scattering intensity of PAL/PL complexes. Fluoresceinisothiocyanate-dextran (FITC-dextran) release from cubic phase containing PAL/PL (3/7, v/v) was relatively high under an acidic and an alkali condition but the release was significantly suppressed under a neutral condition (e. g., pH 7.0), where maximum complexation was observed. The complex formed in the water channel of the cubic phase is believed to control the release in response to a change in the pH of release medium.