Hydrophobically Modified Carbon Dots as Multifunctional Platform for Serum-Resistant Gene Delivery and Cell Imaging
To develop novel multifunctional gene delivery system with high efficiency is of great importance. Due to the unique physical and optical properties of carbon dots (CDs), the CDs prepared from polyethyleneimine (PEI) was modified with various hydrophobic chains with different substitution degrees via epoxide ring-opening reaction. The modification and substitution degree were confirmed by several analytic methods including 1H NMR, FT-IR, TEM, and XPS. These CDs were utilized as multifunctional safe and efficient non-viral gene vectors. Results showed that these materials possess the capability of dual-channel imaging, which enable the intracellular tracking of the delivered DNA. Both the type and substation degree of the hydrophobic chain have large influence on their transfection efficiency. Among the prepared CDs, Ole1.5-CD gave the highest transfection efficiency, which was up to 200 times higher than PEI 25 kDa in the presence of serum in A549 cells. Meanwhile, these CD materials showed much less cytotoxicity and better serum tolerance than classic cationic polymeric gene vector. Cellular uptake assay further confirmed the good serum tolerance and structure-activity relationship of the CD materials. These CDs with good biocompatibility, self-imaging and high gene transfection efficiency may serve as promising reagent for both gene delivery and bio-imaging.