Bioimaging of 5 fluorouracil conjugated to CdTe quantum dots in MCF-7 breast cancer cells

Abstract

Development of a single molecule tracing methods in vitro and in vivo is a challenging task and it has attracted the attention of scientists all over the world. Here we made an attempt to develop a system to trace a single molecule of 5-fluorouracil (an anti cancer agent) by conjugating it to fluorescent nano crystals called Quantum dots (QDs). In the present work we are reporting for the first time the conjugation of an anti-cancer drug, 5-fluorouracil which has specificity to enter nucleus, to CdTe QDs and analyzed their localization in breast cancer cell line, MCF-7, by confocal microscopy. 3-Mercapto propionic acid (3-MPA) capped CdTe QDs were prepared and characterized. 5-fluorouracil having the -NH (Imide) functional group is thought to bonded with -COOH of 3-MPA in the presence of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC). The conjugation is confirmed by absorbance and emission properties of conjugates. FTIR spectra analysis has given clear evidence that free functional groups on 5-fluorouracil are bonded with NH2 group of EDC to form amide bond in comparison to unconjugated QDs and the drug. This forms an indirect evidence for QDs and drug conjugation. For analyzing the localization of QD-5-fluorouracil conjugates, breast cancer cells (MCF-7), were incubated for 12, 24 and 48 h. Cell were also incubated with DAPI, a nuclear stain, to have clear borders of nuculeus. These studies clearly revealed an entry of QD-drug conjugates in to the nucleus of cancer cells. Copyright © 2012 American Scientific Publishers All rights reserved.