Facile green synthesis of fluorescent carbon quantum dots from citrus lemon juice for live cell imaging

Facile and green one pot hydrothermal method was used for synthesis of fluorescent carbon quantum dots (CQDs) using citrus lemon juice as precursor. The synthesized CQDs were characterized using UV–Vis spectrophotometer, fluorescence spectrometer, transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectrometer (FTIR), field emission scanning electron microscope equiped with energy dispersive X-ray spectroscopy (FESEM-EDS) and fluorescence microscopy. The obtained CQDs have high photoluminescence of 10.20% quantum yield. The photoluminescence intensity of CQDs depends on pH of the solution and maximum intensity obtained at pH of 6. The particle size of the carbon dots were distributed in narrow range of 2–10 nm with an average of 5.8 nm. The highly water soluble CQDs have high cell viability even at high concentration which rich up to 85%. MTT assay was used to investigate the potential application of CQDs and the results indicated that the material can be used as florescent probe in the cell imaging.