Dual stimuli-responsive biotinylated polymer-drug conjugate for dual drug delivery

Stimuli-responsive nanoscale polymer-drug conjugates are one of the most promising alternatives in the realm of advanced therapeutics, rendering several characteristics such as spatio-temporal control over drug release, reduced off-target toxicity, enhanced bioavailability, and longer blood circulation time of the drug. Fostered by the aforementioned conceptualization, our quest to develop an ideal polymer-drug conjugate has originated the present investigation of developing a reactive oxygen species (ROS) and esterase-responsive self-assembled polymer-drug (chlorambucil, CBL) conjugate with biotin pendants (DP2) for cancer cell targeting, surrogating another antineoplastic drug, doxorubicin (DOX) via physical encapsulation (DP2@DOX). The ROS and esterase trigger not only released the covalently stitched CBL but also resulted in DOX release by dismantling the amphiphilic balance of the nanoaggregates. Biotinylation-mediated enhancement of cellular uptake of DP2@DOX was reflected in the synergistic anticancer activity of both the drugs (CBL and DOX) in HeLa cells (biotin receptor-positive cells) compared to HEK 293T cells (biotin receptor-negative cells). Furthermore, the selective internalization of the fluorophore-tagged DOX-loaded polymer (DP4@DOX) in HeLa cells compared to HEK 293T cells was confirmed by confocal microscopy and flow cytometry. In summary, the present investigation demonstrates a state-of-the-art self-assembled polymer-drug conjugate as a next-generation dual stimuli-responsive drug delivery vehicle. Esterase and reactive oxygen species-responsive polymer-chlorambucil conjugates form self-assembled nanoaggregates, which surrogate another anticancer drug, doxorubicin, and show synergistic anticancer activity by receptor-mediated endocytosis.