Polycatechol Mediated Small Interfering RNA Delivery for the Treatment of Ulcerative Colitis

Abstract Small interfering RNA (siRNA)‐based therapeutics has high potency and specificity in silencing target genes for the treatment of various diseases; however, the design of efficient and safe carriers for siRNA delivery remains grand challenges. In this study, a family of cationic polycatechols are designed and synthesized using different direct polymerization methods for siRNA delivery in vitro and in vivo. It is observed that the introduction of multiple catechol moieties into cationic polymers could enhance their siRNA binding capability, thus greatly improving the biological stability, cell internalization, and gene silencing efficiency of their complexes. The flexibility of the backbone in polycatechols is also found to influence the whole siRNA delivery process. After screening, the lead cationic polycatechol P1 with a 50% catechol molar ratio could efficiently deliver siRNAs into different cell lines and downregulate various target genes even in the presence of serum proteins. Besides, P1 is also able to successfully silence tumor necrosis factor‐α in macrophages in vitro and in vivo, and efficiently mitigate the symptoms without causing adverse effects in a dextran sodium sulfate‐induced ulcerative colitis model. The results demonstrate that those polycatechols could be developed as a promising class of siRNA delivery systems for gene therapy.