We have prepared the carboxylate nanodiamond (ND-COOH ) and demonstrated the enhanced endocytic fluorescence in living Hela cells by using confocal fluorescence microscopy imaging and transmission electron microscopy (TEM) techniques. The fluorescence enhancement of ND-COOH is observed during the staining dynamics of living cells using confocal fluorescence microscopy. Furthermore, the intracellular localization of ND-COOH in endocytic cells is verified by TEM and the three-dimensional (3D) optical sectioning image of confocal fluorescence microscopy. The low cytotoxicity and high photostability have also been clearly demonstrated. The characterization and the analysis of microscopy provide the unique direct evidence that the ND-COOH can enter living cells though the endocytosis process and exhibits strong endocytic fluorescence. This study would open up new avenues towards the application of functional ND in living cell labelling or drug delivery system.

Journal of Nanoscience and Nanotechnology, Volume 16, Number 7, July 2016, pp. 6748-6754(7)