Parisa Pournemat - Faculty of life sciences and biotechnology, shahid Beheshti university G.C., Tehran, Iran.
Zeinab Bagheri - Faculty of life sciences and biotechnology, shahid Beheshti university G.C., Tehran, Iran
Hamid Latifi - Laser & Plasma Research Institute, Shahid Beheshti University, Tehran, Iran.
Maryam Baeri - Toxicology and Diseases Group (TDG), Pharmaceutical Sciences Research Center (PSRC), The Institute of Pharmaceutical Sciences (TIPS), Faculty of Pharmacy, Tehran University of Medical Sciences (TUMS), Tehran, Iran

Imaging living cells is critical for studying disease mechanisms, cancer progress and invasion, and drug discovery. The fluorescence microscopy approach, which utilizes fluorescent dyes for imaging, is one of the essential cell imaging methods. It is necessary for live fluorescence imaging that the dyes used do not interfere with cell activity; however, current live fluorescent dyes have various drawbacks, such as low photostability, high price, low solubility, and limited biocompatibility. Carbon dots, due to their biocompatibility, low toxicity, high solubility in water, and significant fluorescent properties have recently attracted much attention for fluorescent imaging. Carbon dots are widely used in the field of bioimaging both in vitro and in vivo for diagnostic purposes, photothermal and photodynamic therapy and drug/gene carriers. In this research, we synthesized a carbon dot with red emission (R-CDs) by the solvothermal method. The prepared R-CDs are suitable for imaging living cells due to their high quantum yield, low toxicity, and cost-effectiveness. The fluorescent imaging results of cells treated with synthesized red carbon dots confirmed these carbon dots' fluorescent intensity and high optical stability. Furthermore, many survived cells after ۴۸h treatment indicated the carbon dots' low toxicity.

Carbon dot, Live cell imaging, Solvothermal synthesis, Red emission.