Hydrophilic Ethylene Glycol Fragments: A Determinant Affecting the Therapeutic Index of Paclitaxel Prodrug Nanoassemblies.

Prodrug-based nanoassemblies are promising platforms for cancer therapy. Prodrugs typically consist of three main components: drug modules, intelligent response modules, and modification modules. However, the available modification modules are usually hydrophobic aliphatic side chains, which affect the activation efficiency of the prodrugs. Herein, hydrophilic ethylene glycol fragments were inserted between the modification modules and the response modules, and the important effects of hydrophilic fragments on the assembly, drug release, and therapeutic index of the prodrugs were investigated. Notably, the introduction of hydrophilic fragments affected the intermolecular forces of the prodrugs and increased the interaction of hydrogen bonding. In addition, hydrophilic fragments significantly improved the redox drug release profiles, which affected the therapeutic index of the prodrug nanoassemblies. PTX-SS-OA NPs with hydrophilic fragments exhibited increased redox sensitivity, enhanced cytotoxicity, and superior antitumor efficacy. In comparison, PTX-SS-OAL NPs without hydrophilic fragments showed limited redox sensitivity and cytotoxicity but displayed better safety. Overall, the hydrophilic fragment is a critical determinant in modulating the therapeutic index of the prodrug nanoassemblies, which contributes to the development of advanced prodrug nanodelivery systems.