Safe and efficient delivery of
small interfering RNA (
siRNA) is essential to gene therapy towards intervention of
genetic diseases. Herein, we developed a novel cationic
cholesterol lipid derivative (CEL) in which
cholesterol hydrophobic skeleton was connected to
L-lysine cationic headgroup via a hexanediol linker as the non-viral
siRNA delivery carrier. Well-organized CEL/
siRNA nanocomplexes (100-200 nm) were prepared by microfluidic-assisted assembly of CEL and
siRNA at various N/P ratios. The CEL and CEL/
siRNA nanocomplexes have lower cytotoxicity compared with bPEI25k. Delightfully, we disclosed that, in Hela-Luc and H1299-Luc cell lines, the micro-fluidic-based CEL/
siRNA nanocomplexes exhibited high
siRNA transfection efficiency under both serum-free condition (74-98%) and low-serum circumstances (80-87%), higher than that of
lipofectamine 2000. These nanocomplexes also showed high cellular uptake through the caveolae/
lipid-raft mediated endocytosis pathway, which may greatly contribute to transfection efficiency. Moreover, the time-dependent (0-12 h) dynamic intracellular imaging demonstrated the efficient delivery to cytoplasm after lysosomal co-localization. The results indicated that the microfluidic-based CEL/
siRNA nanosystems possessed good stability, low cytotoxicity, high
siRNA delivery efficiency, rapid cellular uptake and caveolae/
lipid raft-dependent internalization. Additionally, this study provides a simple approach for preparing and applying a "helper
lipid-free" cationic
lipid siRNA delivery system as potential nanotherapeutics towards gene silencing treatment of (
tumor) diseases.