Gadolinium-doped carbon quantum dots derived from dextran for magnetic resonance imaging (MRI) contrast agent and fluorescence imaging

Abstract

Noninvasive imaging methods such as magnetic resonance and fluorescence imaging (FI) have received great attention in the diagnosis of diseases. In this research gadolinium-doped carbon quantum dots (CQDs) were synthesized for the application as multimodal magnetic resonance imaging (MRI) contrast agents and FI probes. The CQDs were synthesized by hydrothermal treatment of dextran, polyethyleneimine (PEI), and a Gd-containing drug. The CQDs with sizes below 10 nm have fluorescence emission upon excitation with wavelengths in the range of 340–380 nm. The CQDs preserve their photoluminescence (PL) in environments with different ionic strengths (0.005–0.5 M of NaCl) and pH of 4–9. The CQDs incubated with mouse fibroblast cells successfully penetrated the cells and were used in FI. The CQDs were used as magnetic resonance imaging (MRI) contrast agents and showed a longitudinal relaxivity value of 0.272 mM−1s−1. The results confirmed that the Gd-doped CQDs derived from dextran can be used for multimodal imaging in biomedical diagnosis applications.