Abstracts
Luminescent materials for imaging, sensors and theranostics
Synthesis and effect of the shell thickness of monodispersed bright NaYbF4:Tm3+@NaYF4 core/shell upconversion nanoparticles for bioimaging applicationsYork E. S. Correales1, Henrique L. Piva1, Sajjad Ullah2, Robert Mauricot3, David Neumeyer3, Rute A. S. Ferreira4, Antonio C. Tedesco5, Marc Verelst3, Sidney J. L. Ribeiro6, Rogéria R. Gonçalves5
1Faculty of Philosophy, Sciences and Letters at Ribeirão Preto (FFCLRP-USP), Ribeirão Preto 14040-900, São Paulo, Brazil., 2Institute of Chemical Sciences, University of Peshawar, PO Box, Peshawar 25120, Pakistan, 3Univ Toulouse UPS, Centre d’Élaboration de Matériaux et d’Études Structurales (CEMES-CNRs), BP 94347, Toulouse 31055, France, 4Department of Physics, CICECO, University of Aveiro, Aveiro 3810-193, Portugal, 5Faculty of Philosophy, Sciences and Letters at Ribeirão Preto (FFCLRP-USP), Ribeirão Preto 14040-900, São Paulo, Brazil, 6Institute of Chemistry, São Paulo State University (UNESP), Araraquara 14800-060, São Paulo, Brazil
E-mail: york.correales@usp.br
Lanthanide-based upconversion nanoparticles (Ln3+-UCNPs) can convert near-infrared (NIR) photons into higher energy ultraviolet-visible (UV-Vis) light.1 These nanoparticles are characterized by sharp luminescence peaks, long luminescence lifetimes, and tunable luminescence emissions across the UV-Vis-NIR region.2 Such optical properties lead to reduced autofluorescence and enhanced penetration depth, rendering UCNPs ideal for advanced biomedical luminescence imaging.It has been recently recognized that β-NaYbF4 is the most efficient host material for constructing multiphoton upconversion nanoparticles (UCNPs).3 This host provides a high concentration of Yb3+ sensitizers that increase the absorption cross-section of the nanoparticles to maximize excitation light utilization. However, energy migration (EM) back to the surface is the main limitation of this host, therefore an optically inactive protective shell is necessary. The synthesis and precise size control of β-NaYbF4 nanoparticles, along with the appropriate thickness for the inactive shell, remain areas for further exploration.Here we present the synthesis, surface modification, cell viability assays, and bioimaging application of NaYbF4:Tm3+@NaYF4 core/shell UCNPs.The protection of the 27.2 nm NaYbF4:Tm3+ core UCNPs and the increase in the shell thickness (and core/shell nanoparticles size) from 1.4 to 5.9 nm (from 30.1 to 38.9 nm) using a layer-by-layer shell growth strategy resulted in a concomitant increase in the upconversion luminescence intensity, lifetime, and quantum yield. After surface modification using poly(acrylic acid) polymer, the nanoparticles demonstrated excellent colloidal stability when redispersed in water, borate buffer, and biological media. The cell viability assays demonstrated the low cytotoxicity of our nanoparticles to 3T3 and MDA-MB-231 cell lines. Preliminary bioimaging experiments revealed successful internalization of the nanoparticles by MDA-MB-231 cells, highlighting their potential as candidates for bioimaging applications.References:1) Y.E. Serge-Correales, C. Hazra, S. Ullah, L. Roncalho, S.J.L. Ribeiro. Nanoscale Adv. 2019, 1, 1936–1947.2) Y.E Serge-Correales, S. Ullah, E. P. Ferreira-Neto, H. D. Rojas-Mantilla, C. Hazra, S.J.L. Ribeiro. Mater. Adv. 2022, 3, 2706–2715.3) S. De Camillis, P. Ren, Y. Cao, M. Plöschner, D. Denkova, X. Zheng, Y. Lu, J. A. Piper. Nanoscale 2020,12, 20347-20355
Keywords: Upconversion nanoparticles, monodisperse core/shell nanoparticles, layer-by-layer shell growth, bioimaging, biocompatibility.
Acknowledgments: We gratefully acknowledge the financial support of FAPESP, CNPq, and CAPES. We also acknowledge the institutions where our research was conducted: CEMES-CNRs, IQ-UNESP, USP, and CNET.