A computer-aided, heterodimer-based "triadic" carrier-free drug delivery platform to mitigate multidrug resistance in...

Co-delivering multiple drugs or circumventing the drug efflux mechanism can significantly decrease multidrug resistance (MDR), a major cause of cancer treatment failure. In this study, we designed and fabricated a universal "three-in-one" self-delivery system for synergistic cancer therapy using a computer-aided strategy. First, we engineered two glutathione (GSH)-responsive heterodimers, ERL-SS-CPT (erlotinib [ERL] linked with camptothecin [CPT] via a disulfide bond [SS]) and CPT-SS-ERI (CPT conjugated with erianin [ERI]), which serve as both cargo and carrier material. Next, molecular dynamics simulations indicated that multiple noncovalent molecular forces, including π-π stacking, hydrogen bonds, hydrophobic interactions, and sulfur bonds, drive the self-assembly process of these heterodimers. We then explored the universality of the heterodimers and developed a "triadic" drug delivery platform comprising 40 variants. Subsequently, we conducted case studies on docetaxel (DTX)-loaded ERL-SS-CPT nanoparticles (denoted as DTX@ERL-SS-CPT NPs) and curcumin (CUR)-loaded ERL-SS-CPT NPs (identified as CUR@CPT-SS-ERI NPs) to comprehensively investigate their self-assembly mechanism, physicochemical properties, storage stability, GSH-responsive drug release, cellular uptake, apoptosis effects, biocompatibility, and cytotoxicity. Both NPs exhibited well-defined spherical structures, high drug loading rates, and excellent storage stability. DTX@ERL-SS-CPT NPs exhibited the strongest cytotoxicity in A549 cells, following the order of DTX@ERL-SS-CPT NPs > ERL-SS-CPT NPs > CPT > DTX > ERL. Conversely, DTX@ERL-SS-CPT NPs showed negligible cytotoxicity in normal human bronchial epithelium cell line (BEAS-2B), indicating good biocompatibility and safety. Similar observations were made for CUR@CPT-SS-ERI NPs regarding biocompatibility and cytotoxicity. Upon endocytosis and encountering intracellular overexpressed GSH, the disulfide-bond linker is cleaved, resulting in the release of the versatile NPs into three parts. The spherical NPs enhance water solubility, reduce the required dosage of free drugs, and increase cellular drug accumulation while suppressing P-glycoprotein (P-gp) expression, leading to apoptosis. This work provides a computer-aided universal strategy-a heterodimer-based "triadic" drug delivery platform-to enhance anticancer efficiency while reducing multidrug resistance.