Programming Drug Delivery Kinetics for Active Burst Release with DNA Toehold Switches.

Despite smart drug delivery systems (DDSs) with high delivery efficiency and improved efficacy for chemotherapy, precise drug release in targeted tumor cells in a controllable way is still challenging. In this work, we develop DNA toehold switch-engineered spherical nucleic acid-templated hydrogel (SNAgel) for on-site active burst release of chemotherapeutic (tumor-killing) drugs in target cancer cells. By designing ligand-specific toehold sequences on hybridization chain reaction (HCR)-generated SNAgel, we realize burst release of payloads with a wide range of t1/2 ranging from 60.52 to 5.49 min by active dynamic control of the kinetics. The camouflage of SNAgels with compact DNA shell enables elongated/prolonged blood circulation and targeted accumulation, cell entry, and apoptosis induction in vivo. The enhanced anticancer activity of SNAgels was substantiated in both cancer cell lines and xenografted tumor-bearing mice. This DNA-engineered kinetic control approach sheds new light on developing paradigm-shifting DDSs for cancer therapeutics.