pH-Sensitive Multi-ligand Gold Nanoplatform Targeting Carbonic Anhydrase IX Enhances the Delivery of Doxorubicin to Hypoxic Tumor Spheroids and Overcomes the Hypoxia-Induced Chemoresistance

Hypoxia is a common feature of solid tumors contributing to resistance to chemotherapy. Selective delivery of chemotherapeutic drugs to hypoxic tumor niche remains an unsolved issue. For this purpose, we constructed a gold nanoplatform targeting carbonic anhydrase IX (CA IX) epitope, which is overexpressed in hypoxic tumor cells versus normal tissues. We designed compatible small MW carbonic anhydrase inhibitor ligands (CAI)- and doxorubicin (Dox)- ligands, and optimized protocols for AuNPs efficient decoration to achieve both good targeting ligand density and optimum drug loading, while preserving colloidal stability. The optimized Dox-HZN-DTDP @ Au NPs-LA-PEG2000-CAI (THZN) nanoplatform proved to be very efficient towards killing HT-29 tumor cells, especially under hypoxic conditions as compared to the non-targeted nanoplatform. It also mediated the effective release of doxorubicin in the lysosomes following internalization, as revealed by confocal microscopy. Furthermore, using tumor spheroids as a representative model for hypoxic solid tumors, our THZN nanoplatform enhanced up to 2.5 times the selective delivery of doxorubicin and minimized chemoresistance, showing better tumor drug penetration as compared to free drug treatment. Our technology is the first CA IX-targeted gold nanoplatform for efficient delivery of doxorubicin to hypoxic tumors in a controlled fashion, with the perspective to improve the therapy of solid tumors and minimize chemoresistance.