Sulfur-rich carbon dots as a novel fluorescent imaging probe for distinguishing the pathological changes of mouse-bone cells

Nowadays, the florescent carbon dots (C-dots), as a type of heavy-metal-free nanomaterials, have been widely suggested for biological imaging, but attempts made for detecting and distinguishing bone-related diseases are still rarely reported by previous works. Here, a type of C-dots, featuring rich sulfur content and excellent bone cell affinity, is prepared by one-pot hydrothermal method. Various characterization techniques have been employed to study the structure and fluorescent properties of the sulfur C-dots, which include the X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FT-IR), ultraviolet-visible (UV-vis) absorption, and fluorescence spectra. Our results show that the sulfur C-dots are featured with small particle size at similar to 4 nm and rich sulfur content as high as 24.85%, allowing the C-dots to exhibit excellent stability in the aqueous solution and good compatibility and affinity with bone cells. Moreover, we find the sulfur rich C-dots as the excitation wavelength changes from 270 nm to 460 nm can exhibit emission-tunable colors from blue, green and to yellow, showing a rich choice of fluorescent colors for cell imaging. Together with the advantages of low cytotoxicity behavior and sulfur-rich functionalized groups, the sulfur C-dots have been proposed to act as a fluorescent probe for detecting and distinguishing bone-related diseased cells where bone-related normal and diseased cells after incubated with sulfur rich C-dots are found to emit blue and yellow fluorescence upon excitation at 405 nm and 488 nm, respectively. Unlike previous works that are always reported to use the C-dots for cell imaging, here we have presented new application possibilities of C-dots for distinguishing the diseased cells from the normal cells.