Abstract
Here we report a facile and eco-friendly hydrothermal method for the fabrication of carbon quantum dots (CQDs) and hydrochar from date palm leaves through integrated process. Functional groups, optical behavior, morphological features, thermal properties, and crystallinity of the synthesized CQDs were investigated using Fourier transform infrared spectroscopy, UV-vis spectroscopy, photoluminescence (PL) spectroscopy, transmission electron microscopy (TEM), thermogravimetric analyzer, and X-ray diffractometer. TEM images of CQDs revealed their spherical shape and 5-15 nm size, while PL studies demonstrated their excellent fluorescence properties. The SEM images of date palm leaf-derived hydrochar shown their sphere-shaped nature with 0.5-2 mu m diameter. We investigated the cytotoxic behavior of CQDs using human mesenchymal stem cells (hMSCs) as an in vitro model with MTT assay and acridine orange/ethidium bromide (AO/EB) dual staining. The cell viability results indicate that CQDs do not significantly reduce hMSCs viability, even at a high dose (200 mu g/mL). Also, AO/EB dual staining images show healthy intact nuclei in CQDs treated and untreated cells. These results confirmed the cytocompatibility and suitability of CQDs for biomedical applications. Due to CQDs fluorescent behavior, we used CQDs as fluorescent probes for cell imaging. Overall, these results demonstrate the applications of CQDs for bio-imaging of normal and cancer cells.