Development of multicolor carbon nanoparticles for cell imaging

Multicolor carbon nanoparticles (CNPs) were prepared, characterized and developed as fluorescent probes for cell imaging. The fluorescent CNPs were prepared with a facile hydrothermal oxidation route by using linear polysaccharide cellulose and cyclic oligosaccharide cyclodextrin as carbon sources. The characterizations by transmission electron microscopy show that the prepared cellulose-CNPs and cyclodextrin-CNPs are spherical, well-dispersed in water with average diameters of 100 nm and 76 nm, respectively. Under the excitation of UV light, the CNPs are strongly luminescent with an excitation-dependent emission behavior and bathochromic emission properties. The fluorometric methods show that the cellulose-CNPs and cyclodextrin-CNPs are strongly fluorescent with fluorescence quantum yield of 7.47% and 4.49%, respectively. The multicolor CNPs have excellent photostability toward photobleaching. Strong near-infrared fluorescence of the carbon nanoparticles was observed with a 632.8 nm excitation wavelength laser. The oxidative metal ions like Hg(II), Cu(II) and Fe(III) show an quench effect on the fluorescence intensity of the CNPs. The multicolor CNPs were successfully used as fluorescent probes for mouse melanoma cells imaging. The results indicate that the multicolor CNPs derived from cellulose and cyclodextrin may have a great potential for the applications in bioimaging.