Quercetin conjugated fluorescent nitrogen-doped carbon dots for targeted cancer therapy application

In this work, we report the development of nitrogen-doped carbon dots (NDCDs) as a drug carrier using quercetin (QC) as a model drug for anti-cancer drug delivery application. NDCDs were prepared by a simple hydrothermal method using Luffa acutangula as a carbon source. The characterization of QC-NDCDs was done by UV-vis spectroscopy, fluorescence spectroscopy, zeta potential measurements, high-resolution transmission electron microscopy (HR-TEM), Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), and Raman spectroscopy. The as-synthesized NDCDs have a small particle size with hydroxyl and nitrogen-containing groups (pyridinic and amide groups), enhancing the fluorescence properties, and were obtained in a good quantum yield (14%). Furthermore, the in vitro alamarBlue® assay revealed that the NDCDs-QC conjugate was nontoxic to colon cancer cells. This NDCDs-QC conjugate is able to kill cancer cells in the NDCDs-QC form compared to free QC as confirmed by in vitro MTT assay results. Thus, the developed NDCDs conjugate can be used as a promising drug delivery and bio-imaging vehicle in cancer therapy.