la060066t_si_001.pdf (1.77 MB)
Thermosensitive Properties of Poly(amidoamine) Dendrimers with Peripheral Phenylalanine Residues
journal contribution
posted on 2006-05-23, 00:00 authored by Yohei Tono, Chie Kojima, Yasuhiro Haba, Toshinari Takahashi, Atsushi Harada, Shigeyuki Yagi, Kenji KonoDendrimers are unique polymers with globular shapes and well-defined structures. We previously prepared poly(amidoamine) (PAMAM) dendrimers having phenylalanine (Phe) residues at every chain end of the dendrimer as
efficient gene carriers. In this study, we found that Phe-derivatized PAMAM dendrimers change their water solubility
depending on temperature. The dendrimers were soluble in aqueous solutions at low temperatures, but they became
water-insoluble at temperatures above a specific threshold, which is termed the lower critical solution temperature
(LCST). Although the LCST of Phe-modified dendrimers decreased with increasing dendrimer generation, these
dendrimers exhibited an LCST of 20−30 °C under physiological conditions. In addition, the LCST of the dendrimers
was controlled by introducing isoleucine (Ile) residues at chain ends of dendrimers at varying ratios with respect to
Phe residues. The PAMAM dendrimers are known to encapsulate various drug molecules. For these reasons, temperature-sensitive dendrimers might be useful as efficient drug carriers with controlled size and temperature-responsive properties.