Spermine‐Based Nanocarriers for siRNA Delivery in Fibroblast‐Driven Diseases: A Proof‐of‐Concept Study

ABSTRACT The development of nanocarriers for nucleic acid delivery has gained significant attention as a promising strategy to regulate protein expression. Small interfering RNA (siRNA) is a powerful tool for gene silencing; however, it is rapidly degraded in the human body and cannot passively cross cell membranes due to its size and strong negative charge. To protect siRNA and facilitate intracellular delivery, a spermine‐based polyacrylamide with a hydrophobic side chain was utilized as a carrier system. This polymer demonstrated high encapsulation efficiency, forming nanoparticles below 150 nm in size with a slightly positive zeta potential and low polydispersity at N/P ratios of 5 and 7. Additionally, the formulation process proved to be highly reproducible and scalable using a microfluidic mixing method. Moreover, siRNA‐polyplexes exhibited good biocompatibility and maintained high cell viability post‐transfection. In vitro, they demonstrated strong knockdown efficiency in murine fibroblasts (L929), murine lung epithelial cells (MLE12), human lung adenocarcinoma cells (A549), and human cervix adenocarcinoma cells (HeLa‐GFP). Furthermore, the polyplexes promoted rapid cellular uptake and efficient endosomal escape, ensuring effective intracellular delivery. Given the therapeutic potential of siRNA, particularly for diseases lacking effective treatments, this approach holds significant promise for targeting solid tumors and fibrotic disorders.