Tumor cell targetting using folate conjugated core/shell CdSe/CdS/ZnS nano rods

Core-shell-shell nano rods have been widely investigated as fluorescent biomarkers, due to their photochemical stability and high brightness, which makes them a good alternative to organic fluorophores. There are several unique optical properties that can make nano rods (NRs) potentially more appealing bioimaging probes. Hydrophobic core-shell-shell CdSe/CdS/ZnS nano rods (NRs) were synthesized by successive ion layer adsorption and reaction (SILAR) technique. Synthesized NRs (CdSe/CdS/ZnS) were made water dispersible by ligand exchange with thioglycolic acid and were conjugated with folic acid (FA) using EDC/NHS techniques for targeting human cancer cells expressing folate receptor (FR). The Folate receptor (FR) is ideally suited for this study because it is preferentially expressed with high binding affinity for folic acid in several cancers. In vitro cytotoxicity of the folate-conjugated CdSe/CdS-TGA and CdSe/CdS/ZnS-TGA NRs were investigated also by employing MCF-7 cells (Breast cancer cell line) through the 3-(4,5- dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. This assay shows that core-shell-shell (CdSe/CdS/ZnS) NRs are biocompatible than core- shell (CdSe/CdS) for targeting the cancer cells. The result of MTT viability assay shows that the percentage of living cells gradually decreases for CdSe/CdS rods where as in case of CdSe/CdS/ZnS rods ≥ 80% percentage of cell viability has been observed. These experiments confirms that FA conjugated NRs are preferentially internalized by MCF-7 tumor cells suggesting their potential utility as targeted fluorescent imaging agent for early stage cancer detection. The MTT cell viability assay indicated that covering the CdSe/CdS rods with ZnS shell reduces their cell toxicity.