The early diagnosis of tumors, i.e. the detection in biological liquids of low concentrations of tumor markers or cells, is a challenge that can be tackled by developing magnetic-fluorescent nanotools for cell/tumor marker sorting. A magnetic-fluorescent nano-system would perform at the same time separation and detection of cells or analytes while its nanoscale size would offer higher surface to volume ratio, thus higher sensitivity should be achieved. In this view we have recently reported a procedure to cluster superparamagnetic nanoparticles into polymer nanobeads. The diameter of the nanobeads can be controlled in a wide range between 40 and 400 nm. As a further step, we have now developed a procedure to aggregate together magnetic iron oxide nanoparticles and fluorescent quantum dots.
The difference in size and surfactants at the surface of the nanocrystals allows the aggregation of magnetic nanoparticles first into the core of the nanostructures, while the QDs are rather distributed in the polymer shell thus allowing the physical separation of the two types of nanocrystals and avoiding possible quenching problems. The surface of the nanobeads of about 100 nm in diameter was then further functionalized with folic acid, a small vitamin which can specifically target cancer cells over-expressing folate-receptors. Cell imaging by confocal and transmission electron microscopy together with competitive test just confirmed the specific uptake of the folic acid-functionalized magnetic-fluorescent nanobeads. Additionally in cell sorting experiments, thanks to the fast magnetic accumulation and specificity, the trifunctional nanobeads exhibit highly efficiency in cell separation, even at a low percentage (up to 1% on 100000 cells in total) of the targeted cells with respect to non-targeted ones. This nanotool will be further exploited for the separation of stem cells.
Relevant papers of the Nanochemistry Department on this highlight:
- R. Di Corato et al., “Multifunctional Nanobeads Based on Quantum Dots and Magnetic Nanoparticles - Synthesis and Cancer Cell Targeting and Sorting”, ACS Nano. 2011, 5 (2) 1109-1121
- R. Di Corato et al., “Acidic Magnetic-Fluorescent Colloidal Nano-Beads: Preparation and Exploitation in Cell Separation Experiments”, Macromolecular Bioscience., 2009, 9, 952-958
- T. Pellegrino “Nanocapsule colloidali magnetiche fluorescenti: procedimento per la loro preparazione e loro impiego in saggi di selezione cellulari” TO2009A000169 (patent filed on 06-03-2009)