Upconversion Nanoparticles Y2O3 and Gd2O3 Co-Doped with Er3+ and Yb3+ with Aminosilane-Folic Acid Functionalization for Breast and Cervix Cancer Cells Detection

The upconversion nanoparticles (UCNPs) possess the ability to absorb near infrared energy (980 nm) and upconvert it to emit in the visible spectra. In this research, the UNCPs emit in red (660 nm) due to the electronic transitions between two rare earth ions: Er3+ and Yb3+, this process is called energy transfer upconversion (ETU). The UCNPs were functionalized with aminosilanes and folic acid receptors (UCNP-FR) and analyzed by transmission electron microscopy, Fourier transform infrared spectroscopy and luminescence measurements. UCNPs-FR of Y2O3 have a particle size of 70 ± 10 nm and the Gd2O3 have a 50 ± 10 nm particle size. Both showed a good luminescence spectrum in comparison with the bare ones. Cytotoxicity of different amounts between 0.001 μg/ml to 1 μg/ml of bare and functionalized UCNPs was measured with the colorimetric assay MTT in three cancer cell lines: human cervical adenocarcinoma (HeLa), human breast cancer cells MB-MDA-231. Some concentrations of bare UCNPs were cytotoxic for cancer cells; however after their functionalization they resulted to be non-cytotoxic. The functionalized UCNPs were able to bind to folate receptors which are overexpressed in cervical and breast cancers cells. It was demonstrated by confocal microscopy, that the functionalized UCNPs were internalized into the cancer cells, confirming that they can be used as biolabels for breast and cervical cancer cells.