In vitro cell imaging and in vivo distribution of carbogenic dots

Objectives Carbon dots(C-dots) is the recently found QD-like fluorescent nanomaterial which had shown the advantage of non-blinking and low cytotoxicity [1-3]. Besides making further evaluation on the cytotoxicity, this study aimed to evaluate the in vitro cell imaging and in vivo animal distribution of C-dots.

Methods The C-dots was synthesized using a novel protocol reported previously by us [4]. In vitro, its cytotoxicity was evaluated using MTT assay and under laser confocal microscopy (LSM) its intra-cellular location in KB cell was investigated by labeling major organelles with different dyes. In vivo, distribution in CD-1 mice was researched by observing the fluorescence in tissue slice with LSM after 6 hours intravenously injection.

Results The MTT assay showed that C-dots were nearly non-toxic at the concentration of 2- 200ug/ml cultivated with KB cells and HepG2 cells in 48h. In vitro cell imaging by LSM, C-dots could be clearly detected inside the KB cells at the concentration of 20ug/ml, most of the particle were located inside the lysosome and few were uniformly distributed around cytosol, endoplasmatic reticulum, mitochondria and Golgi body, none was detected in nucleus. In vivo distribution, C-dots were located predominantly in the spleen, lesser in other major organs including noteworthy the brain.

Conclusions As mitochondria and cell nucleus are considered as major cell compartments relevant for possible nanoparticle-induced toxicity [5]. The specific location of C-dots in lysosome instead of other organelles may account, in part, for its low cytotoxicity. Its extensive distribution in vivo suggested that the long-term internal distribution and toxicity experiments are acquired prior to clinical application