A Novel Fluorescent Quantum Dot Probe for the Rapid Diagnostic High Contrast Imaging of Tumor in Mice.

A simple probe - antibody conjugated silica over coated cadmium selenide quantum dots (QD-Ab probe) for efficient and rapid diagnostic in vivo imaging of tumors is developed. Compared to unconjugated quantum dots (QD), these probes underwent efficient cellular internalization and tumor targeting behavior, retaining bright emission under in vivo cancer models. Silica over coated cadmium selenide quantum dots were conjugated with Epidermal growth factor receptor (EGFR) monoclonal antibody to detect the over expression of EGFR in cancer models. The in vitro cellular internalization efficiency of QD and QD-Ab probe in cultured stem cells (RADMSCs) and cancer cells (HeLa) were assessed by ICP-OES and cLSM. Results demonstrated a greater internalization efficiency of CdSe-Silica QD-Ab probe than CdSe-Silica QDs. For in vivo imaging solid tumor bearing mice was subjected to tail vein injection of QD and QD-Ab probe. After the specific time interval of injection, mice were anesthetized and subjected into Xenogen IVIS®200 imaging system, followed by ex vivo imaging. Subsequently, ultrathin sections of tumor were imaged by using cLSM. Both in vivo and ex vivo imaging results confirmed the tumor-targeted imaging efficiency of QD-Ab probes compared to unconjugated QDs.