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

Abstract

Herein we report the possibility of using green and red emitting silica-coated cadmium selenide (CdSe) quantum dots (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 silica-coated CdSe 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 characteristics 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 green and red emitting silica-coated CdSe QDs were efficiently taken up by the cells and exhibits excellent fluorescence from the cytoplasm. Subsequently, 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) under cLSM. Overall, these in vitro and in vivo results are represented with focus on efficient cellular imaging, cellular localization and even distribution of the green and red emitting silica-coated CdSe QDs in tumor, and comparatively red emitting is exhibits higher fluorescence than green emitting one, in view of their potential applications in cellular imaging in cancer and other diseases.