Upconversion Nanoparticles Y 2 O 3 and Gd 2 O 3 Co-Doped with Er 3+ and Yb 3+ with Aminosilane-Folic Acid Functionalizat
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Upconversion Nanoparticles Y2O3 and Gd2O3 Co-Doped with Er3+ and Yb3+ with Aminosilane-Folic Acid Functionalization for Breast and Cervix Cancer Cells Detection D. Chávez-García1, K. Juárez-Moreno2,* and G.A. Hirata2 1
Centro de Investigación Científica y de Educación Superior de Ensenada. Carretera EnsenadaTijuana 3918 Zona Playitas. Ensenada, Baja California, C.P. 22860, México. E-mail: [email protected] 2 Centro de Nanociencias y Nanotecnología, Universidad Nacional Autónoma de México, Carretera Tijuana-Ensenada. Km. 107, Ensenada, Baja California, C.P. 22860, México. E-mails: [email protected], [email protected]. * CONACyT Research Fellow at CNyN-UNAM, Member of the International Network of Bionanotechnology with impact in Biomedicine, Food and Biosafety (CONACyT), México.
ABSTRACT 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. UCNPsFR 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. INTRODUCTION In the recent years, the upconversion luminescence nanoparticles have gain great interest due to the wide range of applications in biomedicine, this applications may vary from biolabels for cancer cell detection to fluorescence imaging and drug delivery [1-2]. The synthesis of UCNPs was done by combining two rare earth ions in a proper host, in this case an oxide; the first ion (sensitizer) absorbs near-infrared energy (NIR) and transfers it to the second ion; then the nanoparticle emits the excess of energy as photons in the visible range [3]. In this work, the host Y2O3 was codoped with Yb3+ (10% mol), as sensitizer, and Er3+ (1 % mol). Also, the host Gd2O3 was co-doped with Yb3+ (10% mol) and Er3+ (1 % mol), both hosts were prepared by solgel method [4-5]. The upconversion process begins when the ion Yb3+ absorbs NI
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