Biodegradable unimolecular reversed micelle

33 pH-Sensitive Unimolecular Reversed Micelle with Size-Selective Encapsulation Ability 

Congo red (CR), are discussed from the viewpoint of the unimolecular reversed micelle property of 25. 

The encapsulation amounts of RB per 25a-c ([RB]/[25]) were 27.9 for 25a, 30.0 for 25b, and 21.6 for 25c. 25b more efficiently encapsulated RB than did 25a and 25c. The DS value of 25a was 46.0%, which was lower than the expected value when all the external hydroxyl groups of Poly la were reacted (about 51%), indicating that a somewhat denser shell was required to encapsulate many dyes. In contrast, the lower encapsulation values of 25c were ascribed to the fact that the higher DS value of 25c led to a narrower hydrophilic interior than in 25b. 

The encapsulation ability of 25 was also examined using other water-soluble dyes, such as TB, AY, MB, and CR. Although TB and AY were readily encapsulated by 25 as well as RB, MB and CR were not encapsulated because these dyes had greater extended structures than the other dyes. The results indicated that the encapsulation ability of 25 toward these dye molecules 

The encapsulation ability of 25 toward water-soluble dyes indicated that 25 was a unimolecular reversed micelle with an encapsulation abihty toward hydrophilic dye molecules. In addition, 25 showed a molecular size-selective encapsulation ability and a pH-sensitive controlled-release property. Hence, 25 was a good candidate for mixture-separation systems and pH-sensitive controlled-release systems. 

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