Quaternized poly(propylene imine) dendrimers as novel pH-sensitive controlled-release systems

Quaternized poly(propylene imine) dendrimers have been prepared and investi gated for their ability to function as pH-responsive controlled-release sys tems. These functionalized dendrimers are able to solubilize pyrene due to charge transfer complexation between the probe and the tertiary amino group s of the dendrimeric branches. The introduction of the quaternary ammonium groups at the external surface of the dendrimers affects the protonation ti tration profile as compared to the parent compounds leading to the release of the entrapped pyrene within a narrow pH region and basically when the in termediate nitrogens are protonated. These properties render these material s promising candidates for pH-responsive controlled-release systems possibl y including prospected drug delivery applications.