Facile synthesis of gold/gadolinium-doped carbon quantum dot nanocomposites for magnetic resonance imaging and photothermal ablation therapy

Abstract

Composites of gold nanomaterials and imaging agents show promise in cancer therapy. Here we have demonstrated a rapid, facile, environmentally friendly, and organic solvent-free method for the synthesis of a gold/gadolinium-doped carbon quantum dot (Au/GdC) nanocomposite for magnetic resonance imaging (MRI) and photothermal ablation (PTA) therapy. The gadolinium-doped carbon quantum dots (Gd@CQDs) were synthesized using a one-pot, microwave-assisted method, and used as reducing and stabilizing agents to both form the Au/GdC nanocomposite and prevent its agglomeration. Formation of the Au/GdC nanocomposite is achieved by simple mixing of Gd@CQDs and a gold precursor, without the addition of any other reducing agents, surface passivating agents, surfactants, or organic solvents. The Au/GdC nanocomposite shows paramagnetism, surface plasma resonance in the near infrared region (NIR), and excellent photostability. Furthermore, it provides high longitudinal relaxivity (r₁ = 13.95 mM⁻¹ s⁻¹), indicating its potential for use as a T₁ contrast agent in MRI. Furthermore, in vitro and in vivo studies using HeLa cells and zebrafish embryos as cancer and animal cell models, respectively, confirmed the low toxicity and excellent biocompatibility of the Au/GdC nanocomposite. Notably, our results demonstrate the ability of the Au/GdC nanocomposite to efficiently destroy cancer cells using PTA. Therefore, this work reveals a simple and powerful strategy to fabricate an Au/GdC nanocomposite for MRI and photothermal ablation of cancer cells.