Comparative Studies of High Contrast Fluorescence Imaging Efficiency of Silica-coated CdSe Quantum Dots with Green and Red Emission

Herein we report the possibility of using green and red emitting Cadmium selenide (CdSe)- Silica core-shell quantum dots (abbreviated as CS QDs) for remarkable stem and cancer cellular imaging, efficient cellular uptake and fluorescence imaging of semi and ultra-thin sections of tumor for in vivo tumor targeted imaging applications. The comparative studies of high contrast cellular imaging behaviours of the CS QDs with green and red emission have been exploited to visualize rabbit adipose tissue-derived mesenchymal stem cells (RADMSCs) and human cervical cancerous (HeLa) cells in vitro. The in vitro cellular uptake features of QDs were performed in cultured HeLa cells using Confocal Laser Scanning Microscopy (cLSM) after staining with 4,6-diamidino-2-phenylindole (DAPI). The in vitro cellular imaging and uptake results showed that the both green and red emitting CS QDs were efficiently taken up by the cells and exhibits excellent emission from the cytoplasm. Successively, the in vivo tumor targeting was conducted using both QDs, of Dalton’s Lymphoma Ascites (DLA) cells bearing solid tumor mice. Fluorescence imaging and effective tumor targeting characteristics of QDs at tumor site were confirmed by the semithin (~15 μm thickness) and ultrathin sections of tumor (~100 nm thickness) observed under cLSM. Generally, these in vitro and in vivo results are presented for showing the efficient cellular localization of the green and red emitting CS QDs in tumor. Found that the red emitting QDs is exhibit stronger fluorescence than green emitting one. These observations shed light in their potential applications for cellular imaging of tumor cells.