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

In the past decade, graphene quantum dots (GQDs), have emerged as a promising carrier for gene delivery with imaging capabilities in cancer therapeutics [1, 2]. GQDs are zerodimensional nanostructures, consisting of few layers of graphene sheets with lateral dimensions generally below 20 nm. Due to the presence of a carbon lattice and, often, oxygen functional groups, GQDs have the capability to bind a variety of molecules through π-π stacking or electrostatic interactions. GQDs exhibit minimal toxicity in vitro and in vivo due to their smaller size and rapid excretion [3]. These properties render GQDs ideal candidates for the delivery of different therapeutic platforms. In addition to being a delivery agent, GQDs can also be utilized for imaging and biosensing. They are photostable and exhibit intrinsic fluorescence in the visible (VIS) and near-infrared (NIR), which can serve as a non-invasive detection and tracking mechanism [4, 5]. Several GQD-based optical sensors have recently been developed for the detection of RNA [6], ssDNA [7], miRNA [8], proteins [9], and small molecules [10, 11]. These advantageous properties of GQDs have not been fully utilized to date for small interfering RNA (siRNA) delivery, specifically those targeting Epidermal growth factor receptor (EGFR) and Kirsten rat sarcoma virus (KRAS), that can perform well against a variety of cancer types. This study aims to fill this gap by exploring the properties of GQDs, doped with nitrogen and neodymium, as standalone multifunctional agents for siRNA delivery with imaging capabilities in VIS/NIR spectral regions.