Target-Specific Gene Silencing of Layer-by-Layer Assembled Gold–Cysteamine/siRNA/PEI/HA Nanocomplex

Target-specific intracellular delivery of small interfering RNA (siRNA) is regarded as one of the most important technologies for the development of siRNA therapeutics. In this work, a cysteamine modified gold nanoparticles (AuCM)/siRNA/polyethyleneimine (PEI)/hyaluronic acid (HA) complex was successfully developed using a layer-by-layer method for target-specific intracellular delivery of siRNA by HA receptor mediated endocytosis. Atomic force microscopic and zeta potential analyses confirmed the formation of a AuCM/siRNA/PEI/HA complex having a particle size of ca. 37.3 nm and a negative surface charge of ca. −12 mV. With a negligible cytotoxicity, AuCM/siRNA/PEI/HA complex showed an excellent target-specific gene silencing efficiency of ca. 70% in the presence of 50 vol % serum, which was statistically much higher than that of siRNA/Lipofectamine 2000 complex. In the competitive binding tests with free HA, dark-field bioimaging and inductively coupled plasma–atomic emission spectroscopy confirmed the target-specific intracellular delivery of AuCM/siRNA/PEI/HA complex to B16F1 cells with HA receptors. Moreover, the systemic delivery of AuCM/siRNA/PEI/HA complex using apolipoprotein B (ApoB) siRNA as a model drug resulted in a significantly reduced ApoB mRNA level in the liver tissue. Taken together, AuCM/siRNA/PEI/HA complex was thought to be developed as target-specific siRNA therapeutics for the systemic treatment of various liver diseases.