Steered Molecular Dynamics Investigation of Chitosan Nano-Carrier Mediated siRNA Translocation Across Biological Membranes

The delivery of nucleic acids based therapeutics such as siRNA into cells remains a major challenge in gene therapy, primarily due to their hydrophilicity and intrinsic negative charge, which hinder membrane translocation. Chitosan, a biocompatible and biodegradable cationic polysaccharide, has emerged as a promising carrier for gene delivery applications. Nevertheless, the optimal stoichiometric ratio between chitosan and siRNA required to achieve efficient membrane penetration has not been fully elucidated. In this study, molecular dynamics simulations were employed to examine the formation of chitosan-RNA complexes and their interactions with a model lipid bilayer. The results indicate that the chitosan-to-RNA ratio has a pronounced impact on the biophysical properties of the complexes, affecting both their structural stability and dynamic interactions with the membrane. Specifically, a 1:3 RNA-to-chitosan ratio (R1C3) was found to facilitate more efficient membrane translocation, whereas a 2:2 ratio (R2C2) produced more stable complexes overall. The findings in this study offer valuable insights for the rational design of chitosan-based siRNA delivery systems and underscore the importance of balancing nucleic acid and carrier content to achieve both stability and effective transmembrane delivery.