▎ 摘　　要

A new nanosheet fluorescent chemosensor (GO-NH-COUR) based on graphite oxide (GO) covalently functionalized with a 4-methyl-7-aminocoumarin (NH2-COUR) has been prepared. The GO were prepared by a modified Hummers method. The products were characterized by TEM, XRD, and FT-IR. The photophysical properties of GO, NH2-COUR and GO-NH-COUR in aqueous and ethanol solution have been investigated by UV/vis spectrophotometry, steady-state and time-resolved fluorometry. They reflect a large effect of the NH2-COUR substituent on the fluorescence characteristics of GO. In aqueous solution, GO-NH-COUR probes undergo protonation-deprotonation in the acid to basic pH range, producing intensity increases with acid to near-neutral pH range. The advantages of the newly pr epared nanoparticles are that they offer good dispersion in aqueous solution and optical properties. Confocal microscopy experiments showed that GO-NH-COUR can be transfected into the living cells and applied for fluorescence imaging. (C) 2014 Elsevier Ltd. All rights reserved.