Y-Shaped Circular Aptamer-DNAzyme Conjugates for Highly Efficient in Vivo Gene Silencing

Oligonucleotide drugs have been used widely as therapeutic agents for gene therapy, while their instability in biological media and inefficiency for intracellular delivery remain major hurdles for practical in vivo applications. Herein, we report a circular Y-shaped aptamer-DNAzyme conjugate (cYAD) for highly efficient in vivo gene silencing via RNA cleavage, which can been employed in various disease treatments, including cancer, inflammation, as well as viral infections. Systematic studies revealed that cyclization of the DNA structure could improve the stability of oli-gonucleotide drugs in vivo. Besides, the bivalent aptamer motifs provided a specific and enhanced tumor cell targeting ability for accumulation and retention of the oligonucleotide drugs at the tumor site. As a proof of concept, a widely applicable Na+-dependent fluorescent sensor, NaA43 DNAzyme, was used to inhibit MET gene expression in mice tumor model tissues, which exhibited highly efficient gene silencing performance in vivo, which confirmed our findings with cYAD. This strategy provides a novel approach for the construction of oligonucleotide drugs for practical therapeutic applications.