A polyvalent aptamer system for targeted drug delivery.

Poor efficacy and off-target systemic toxicity are major problems associated with current chemotherapeutic approaches to treat cancer. We developed a new form of polyvalent therapeutics that is composed of multiple aptamer units synthesized by rolling circle amplification and physically intercalated chemotherapy agents (termed as "Poly-Aptamer-Drug"). Using a leukemia cell-binding aptamer and doxorubicin as a model system, we have successfully constructed Poly-Aptamer-Drug systems and demonstrated that the Poly-Aptamer-Drug is significantly more effective than its monovalent counterpart in targeting and killing leukemia cells due to enhanced binding affinity (≈ 40 fold greater) and cell internalization via multivalent effects. We anticipate that our Poly-Aptamer-Drug approach will yield new classes of tunable therapeutics that can be utilized to effectively target and treat cancers while minimizing the side effects of chemotherapy.