RNA Delivery Using a Graphene Oxide-Polyethylenimine Hybrid Inhibiting Myotube Differentiation

Graphene oxide (GO) conjugated with short polyethylenimine (PEI) chains (GO-PEI) has been designed as a candidate nanocarrier for small interfering RNA (siRNA) delivery to mammalian cells based on the efficient interaction between the positively charged GO-based platform and the negatively charged siRNA. The function and efficiency of siRNA delivery using GO-PEI were compared to those using the positive control Lipofectamine RNAiMax by analyzing the differentiation to myotubes, and myogenin gene and protein expression in C2C12 cells. RNAiMax transfection induced cellularization and reduction of both myogenin gene and protein expression, suggesting that the differentiation of C2C12 cells was triggered by gene silencing. While GO-PEI also promoted cellularization, the myogenin gene expression remained comparable to scrambled controls, whereas the protein levels were higher than those observed with RNAiMax. Mechanistically, we attributed the reduced gene silencing efficiency of GO-PEI to a poor endosomal escape, despite strong siRNA complexation. This limitation was likely due to a low buffering capacity of GO-PEI, as a significant fraction of nitrogen atoms were already protonated, reducing the availability of free amines necessary for endosomal disruption. An appropriate chemical modification to enhance siRNA release from the endosomes is therefore essential for advancing the development of GO-based platforms as versatile and efficient nanocarriers in gene therapy applications.