pH-Sensitive Micelles




   There is increasing interest in pH-sensitive polymers because of their many potential applications in biotechnology, including drug delivery systems and sensors. In particular, micelle-forming pH-sensitive copolymers are very useful tools for targeting the delivery of hydrophobic drugs both to acidic tumor tissues (pH 6.0 to 7.2), compared to normal tissue (pH 7.4), and to the cytoplasm after the release of endosome (pH 5.5). pH-dependent solubility is generally employed in pH-sensitive polymers. Ionization makes polymers with acidic character, such as poly(sulfonamide), soluble above the pKa value but insoluble below it. In contrast, polymers with alkaline character, such as poly(β-amino ester) (PAE) and poly(L-histidine), are insoluble at high pH values but soluble at low ones, due to their ionization properties. In our laboratory, poly(ethylene glycol) was combined with PAE to obtain an amphiphilic block copolymer. The methoxypoly(ethylene glycol)-poly(β-amino ester) block copolymer can form self-assembled micelles depending on the pH value, that is, micelles are formed at a pH of 7.4, but the copolymer is fully solubilized at lower pH values. Doxorubicin-loaded micelles were quite effective in cancer therapy. Using this pH-sensitive micelle, we are trying to evaluate the efficacy for carriers of therapeutic or diagnostic agent.  




Sungkyunkwan University(SKKU)