Abstract
Small interfering RNA (siRNA)-based therapy has been subject of intense research since the discovery of RNA interference (RNAi), providing a tool to potentially silence any chosen gene. Nevertheless, efficient delivery still presents a major hurdle to translating this promising technology into medical practice. Here, we describe a straightforward method to prepare and characterize an effective delivery system consisting of low-molecular-weight polyethylenimine (PEI) and transferrin (Tf). Tf-PEI polyplexes are not only able to successfully transport and protect the sensitive nucleic acid payload from degradation but also to selectively deliver the siRNA to transferrin receptor (TfR)-overexpressing cells, playing key roles in the pathology of numerous cancer types as well as inflammatory diseases.