Synthesis of Self-Targeted Carbon Dot with Ultrahigh Quantum Yield for Detection and Therapy of Cancer.

This study aims to engineer a new type of ultrahigh quantum yield carbon dots (CDs) from methotrexate (MTX-CDs) with self-targeting, imaging, and therapeutic effects on MDA-MB 231 breast cancer cells. CDs were synthesized via a straightforward thermal method using a methotrexate (MTX) drug source. The physicochemical characteristics of the prepared MTX-CDs were studied using Fourier transform infrared (FT-IR) spectroscopy, transmission electron microscopy (TEM), dynamic light scattering (DLS), X-ray powder diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). TEM and DLS revealed which MTX-CDs have homogeneous spherical morphology with a smaller average size of 5.4 ± 2.2 nm, polydispersity index (PDI) of 0.533, and positive surface charge of around +3.93 mV. Results of FT-IR spectroscopy and high-resolution XPS indicated the presence of residues of MTX on CDs. Therefore, the synthesized MTX-CDs could be targeted and be taken up by FR-positive cell lines without the aid of additional targeting molecules. In vitro epifluorescence images demonstrated high-contrast cytoplasm biodistribution of MTX-CDs after 2 h of treatment. A much stronger fluorescent signal was detected in MDA-MB 231 compared to MCF 7, indicating their ability to precisely target FR. The highest cytotoxic and apoptotic effects were observed in MTX-CDs compared to free MTX obtained by the MTT assay, cell cycle arrest, and annexin V-FITC apoptosis techniques. Results revealed that the novel engineered MTX-CDs were capable of inducing apoptosis (70.2% apoptosis) at a lower concentration (3.2 μM) compared to free MTX, which was proved by annexin V and cell cycle. This work highlights the potential application of CDs for constructing an intelligent nanomedicine with integration of diagnostic, targeting, and therapeutic functions.

Déclaration de conflit d'intérêts

The authors declare no competing financial interest.