Cancer Therapeutic siRNA Delivery and Imaging by Nitrogen- and Neodymium-Doped Graphene Quantum Dots

Abstract

While small interfering RNA (siRNA) technology has become a powerful tool that can enable cancer-specific gene therapy, its translation to the clinic is still hampered by the inability of the genes alone to cell transfection, poor siRNA stability in blood, and the lack of delivery tracking capabilities. Recently, graphene quantum dots (GQDs) have emerged as a novel platform allowing targeted drug delivery and fluorescence image tracking in visible and near-infrared regions. These capabilities can aid in overcoming primary obstacles to siRNA therapeutics. Here, for the first time, we utilize biocompatible nitrogen-and neodymium-doped graphene quantum dots (NGQDs and Nd-NGQDs, respectively) for the delivery of Kirsten rat sarcoma virus (KRAS) and epidermal growth factor receptor (EGFR) siRNA effective against a variety of cancer types. GQDs loaded with siRNA noncovalently facilitate successful siRNA transfection into HeLa cells, confirmed by confocal fluorescence microscopy at biocompatible GQD concentrations of 375 μg/mL. While the GQD platform provides visible fluorescence tracking, Nd doping enables deeper-tissue near-infrared fluorescence imaging suitable for both in vitro and in vivo applications. The therapeutic efficacy of the GQD/siRNA complex is verified by successful protein knockdown in HeLa cells at nanomolar siEGFR and siKRAS concentrations. A range of GQD/siRNA loading ratios and payloads are tested to ultimately provide substantial inhibition of protein expression down to 31−45%, comparable with conventional Lipofectamine-mediated delivery. This demonstrates the promising potential of GQDs for the nontoxic delivery of siRNA and genes in general, complemented by multiwavelength image tracking.

Better biocompatibility of nitrogen‐doped graphene compared with graphene oxide by reducing cell autophagic flux blockage and cell apoptosis

“…In terms of cell compatibility, while certain in vitro experiments have shown that C 2 N exhibits cytotoxicity, such as inducing oxidative stress in vascular endothelial cells, 30 significantly inhibiting the proliferation of bladder cancer cells, 31 and causing ferroptosis and inflammatory responses in BV2 microglial cell line, 32,33 other experiments have demonstrated good cell membrane compatibility of C2N, with no effect on blood cell hemolysis, 34 no toxicity to breast cancer cells, 35 and no harm to Wistar albino rats 22 . In summary, C2N has emerged as an important nanomaterial with a wide range of applications in the field of biomedicine 36–42 …”

“…22 In summary, C2N has emerged as an important nanomaterial with a wide range of applications in the field of biomedicine. [36][37][38][39][40][41][42] In our study, we employed GO as a widely used control to perform a systematic comparison of the lethal dosage, tissue distribution, inflammation, and cell injury induced by intravenous administration GO/C 2 N in mice. We extensively assessed and compared these aspects in major organs, such as the liver, kidney, lung, spleen, and…”

A review on synthesis, properties, and biomedical applications of graphene quantum dots (GQDs)

“…Recently, Ahn et al synthesized positively charged N-GQDs from citric acid and PEI, demonstrating successful binding of these N-GQDs with mRNA and pDNA through electrostatic interactions [187]. Similarly, Valimukhametova et al confirmed that N-GQDs and Nd-NGQDs can efficiently form complexes with siRNA through electrostatic interactions [188].…”

Lipid nanoparticles-based RNA therapies for breast cancer treatment

“…After being processed by dedicated enzymes in the cytoplasm, siRNAs bind a sequence of a complementary mRNA by inducing its degradation and preventing the translation in the corresponding protein product. To date, four siRNA-based treatments have been approved by FDA, demonstrating the potential efficacy and safety of this therapeutic approach [146]. Particularly, RNAi through siRNAs appears to be a promising tool to perform a selective gene silencing in the context of targeting tumor-specific mRNAs [84,147].…”