| 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 several
critical factors. These include the inability of cell transfection by the genes alone, 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 the visible and near-infrared. 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) for the delivery of Kirsten rat sarcoma virus (KRAS) and epidermal growth factor
receptor (EGFR) siRNA effective against a variety of cancer types. The non-covalent loading
of siRNA onto GQDs is evaluated and optimized by the electrophoretic mobility shift assay
and zeta potential measurements. GQDs as a delivery platform facilitate successful gene
transfection into HeLa cells confirmed by confocal fluorescence microscopy at biocompatible
GQD concentrations of 375 µg/mL. While the NGQD 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 is 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 non-toxic delivery of siRNA and genes in general, complemented by
multiwavelength image-tracking. |
