Chondroitin sulfate modified calcium phosphate nanoparticles for efficient transfection via caveolin-mediated endocytosis

Efficient transfection remains a challenge for gene delivery in both cell biological scientific research and gene therapeutic fields. Existing transfection strategies rarely pay attention to altering the endocytosis pathway of nanocarriers for transfection efficiency improvement. In this work, we innovatively postulated that calcium phosphate nanoparticles coated with glycosaminoglycan could be internalized by cells mainly through caveolin-mediated endocytosis pathway allowing genes to bypass lysosome route, and hence enhance the transfection efficiency. To achieve this, we developed calcium phosphate nanoparticles (CP-ALN-CS) coated with chondroitin sulfate (CS) and alendronate (ALN) in a modular manner. The CP-ALN-CS had a hydrodynamic size of 131.0 ± 8.7 nm and exhibited favorable dispersity, stability, and resistance to nuclease degradation. Unlike conventional calcium phosphate and PEI-based transfection, CP-ALN-CS exhibited efficient cellular uptake with co-localization in Golgi apparatus and endoplasmic reticulum. Through bypassing the lysosome involved cellular uptake route, CP-ALN-CS can effectively protect genes from degradation and relieve cytotoxicity. After loading plasmid DNA, CP-ALN-CS showed extraordinary transfection efficiency in HEK 293T cells, outperforming the PEI which is considered as the gold standard. The current work provides a novel and facile approach to improve gene transfection efficiency and is valuable for the design of next-generation in vitro transfection reagents.