We have developed an ESIPT based drug delivery system, Cou–Benz–Cbl conjugate, with pH sensitive fluorescence properties and photocontrolled release of the anticancer drug chlorambucil.

Among the well-known phototriggers, the p-hydroxyphenacyl (pHP) group has consistently enabled the very fast, efficient, and high-conversion release of active molecules. Despite this unique behavior, the pHP group has been ignored as a delivery agent, particularly in the area of theranostics, because of two major limitations: Its excitation wavelength is below 400 nm, and it is nonfluorescent. We have overcome these limitations by incorporating a 2-(2'-hydroxyphenyl)benzothiazole (HBT) appendage capable of rapid excited-state intramolecular proton transfer (ESIPT). The ESIPT effect also provided two unique advantages: It assisted the deprotonation of the pHP group for faster release, and it was accompanied by a distinct fluorescence color change upon photorelease. In vitro studies showed that the p-hydroxyphenacyl-benzothiazole-chlorambucil conjugate presents excellent properties, such as real-time monitoring, photoregulated drug delivery, and biocompatibility.

Among the well-known phototriggers,t he phydroxyphenacyl (pHP) group has consistently enabled the very fast, efficient, and high-conversion release of active molecules.D espite this unique behavior,t he pHP group has been ignored as ad elivery agent, particularly in the area of theranostics,b ecause of two major limitations:I ts excitation wavelength is below400 nm, and it is nonfluorescent. We have overcome these limitations by incorporating a2 -(2'-hydroxyphenyl)benzothiazole (HBT) appendage capable of rapid excited-state intramolecular proton transfer (ESIPT). The ESIPT effect also provided two unique advantages:Itassisted the deprotonation of the pHP group for faster release,a nd it was accompanied by adistinct fluorescence color change upon photorelease.I nvitro studies showed that the p-hydroxyphenacyl-benzothiazole-chlorambucil conjugate presents excellent properties,s uch as real-time monitoring,p hotoregulated drug delivery,and biocompatibility.

No abstract