Self-Assembly of polymer-doxorubicin conjugates to form polyprodrug micelles for pH/enzyme dual-responsive drug delivery

ABSTRACT Functionality of polymers is crucially fundamental to polymers. However, the application of polymers faces great challenges due to the insufficient function of hydrophobic chain, especially in drug delivery. One novel approach to solve this dilemma involves the use of medicated hydrophobic chains. Herein, the polymer-doxorubicin conjugates are synthesized from hydrophilic copolymer and hydrophobic chain composed of doxorubicin (DOX). DOX, a common hydrophobic anticancer drug, is used to serve as a hydrophobic pendant for inducing self-assembly of polymer-doxorubicin conjugates. The self-assembly of polymer-drug conjugates is employed to encapsulate the unreacted drug for the first time and form drug-loaded polyprodrug micelles that possess a low critical micelle concentration (CMC), which improves the use efficiency of expensive drug. The detachment of DOX moieties from polymer-doxorubicin conjugates caused by amidase facilitates the disintegration of DOX-loaded polyprodrug micelles to trigger the enhanced release of DOX in a slightly acidic medium. It is demonstrated that the DOX-loaded polyprodrug micelles have a higher suppression against cancer cells in in vitro investigations. This work thus proposes a strategy to modify the poor functionality of polymer-based nanostructures, through designing the medicated hydrophobic chains. This strategy facilitates the potential application of polymer-drug conjugates and provides profound insights into the effect of medicated polymer on drug delivery system.