Double Controlled Release of Therapeutic RNA Modules through Injectable DNA–RNA Hybrid Hydrogel

Advances in the DNA nanotechnology have enabled the fabrication of DNA-based hydrogels with precisely controlled structures and tunable mechanical and biological properties. Compared to DNA hydrogel, preparation of RNA-based hydrogel remains challenging due to the inherent instability of naked RNA. To overcome these limitations, we fabricated a DNA-RNA hybrid hydrogel via stepwise dual enzymatic polymerization. Multimeric short hairpin RNAs (shRNAs) were hybridized with functional DNA aptamers for targeting and mechanical properties of the hydrogel. The obtained DNA-RNA hybrid hydrogel was ultrasoft, robust, and injectable hence reconfigurable into any confined structures. As a model system, the hydrogel was able to mimic microtubule structures under physiological conditions and designed to release the functional small interfering RNA (siRNA)-aptamer complex (SAC) sequentially. In addition, we encoded restriction enzyme-responsive sites in DNA-RNA hybrid hydrogel to boost the release of SAC. This novel strategy provides an excellent platform for systematic RNA delivery through double-controlled release, SAC release from hydrogel, and subsequent release of siRNA from the SAC, which has promising potential in RNA therapy.