Poly(ethyleneimine) functionalized carbon nanotubes as efficient nano-vector for transfecting mesenchymal stem cells.

For gene and drug delivery applications, carbon nanotubes (CNTs) have to be functionalized in order to become compatible with aqueous media and bind with genetic materials. In this study, combination of polyethyleneimine (PEI) grafted multi-walled carbon nanotubes (PEI-g-MWCNTs) and chitosan substrate is used as an efficient gene delivery system for transfection of hard-to-transfect bone marrow mesenchymal stem cells (BMSCs) with enhanced green fluorescent protein (EGFP) gene. Fourier transform infrared (FT-IR) spectra, dynamic light scattering (DLS) analysis and zeta potential measurements are used to characterize binding of PEI, particle size distribution and colloidal stability of the functionalized CNTs, respectively. DNA binding affinity, cellular uptake, transfection efficiency and possible cytotoxicity are also tested by agarose gel electrophoresis, flow cytometry, cytochemisty and MTT assay. The results demonstrate that cytotoxic effect of PEI-g-MWCNTs is negligible under optimal transfection condition. In consistency with high cellular uptake (>82%), PEI-g-MWCNTs give higher delivery of EGFP into the BMSCs which results in a more sustained expression of the model gene (EGFP) in short-term culture. These results suggest that PEI-g-MWCNTs in corporation with chitosan substrates would be a promising delivery system for BMSCs, a cell type with relevancy in the regenerative medicine and clinical applications.