Person:
Torres Vera, Vivian Andrea

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First Name
Vivian Andrea
Last Name
Torres Vera
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Farmacia
Department
Química en Ciencias Farmacéuticas
Area
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Now showing 1 - 2 of 2
  • Publication
    Upconverting Nanoparticles in Aqueous Media: Not a Dead-End Road. Avoiding Degradation by Using Hydrophobic Polymer Shells
    (Wiley, 2021-12-13) Méndez González, Diego; Torres Vera, Vivian Andrea; Zabala Gutiérrez, Irene; Gerke, Christoph; Cascales Sedano, Concepción; Rubio Retama, Jorge; Gómez Calderón, Óscar; Melle Hernández, Sonia; Laurenti, Marco
    The stunning optical properties of upconverting nanoparticles (UCNPs) have inspired promising biomedical technologies. Nevertheless, their transfer to aqueous media is often accompanied by intense luminescence quenching, partial dissolution by water, and even complete degradation by molecules such as phosphates. Currently, these are major issues hampering the translation of UCNPs to the clinic. In this work, a strategy is developed to coat and protect β-NaYF4 UCNPs against these effects, by growing a hydrophobic polymer shell (HPS) through miniemulsion polymerization of styrene (St), or St and methyl methacrylate mixtures. This allows one to obtain single core@shell UCNPs@HPS with a final diameter of ≈60–70 nm. Stability studies reveal that these HPSs serve as a very effective barrier, impeding polar molecules to affect UCNPs optical properties. Even more, it allows UCNPs to withstand aggressive conditions such as high dilutions (5 μg mL−1), high phosphate concentrations (100 mm), and high temperatures (70 °C). The physicochemical characterizations prove the potential of HPSs to overcome the current limitations of UCNPs. This strategy, which can be applied to other nanomaterials with similar limitations, paves the way toward more stable and reliable UCNPs with applications in life sciences.
  • Publication
    Exploring the Origin of the Thermal Sensitivity of Near-Infrared-II Emitting Rare Earth Nanoparticles
    (ACS Publications, 2023-06-30) Hamraoui, Khouloud; Torres Vera, Vivian Andrea; Zabala Gutierrez , Irene; Casillas Rubio , Alejandro; Alqudwa Fattouh , Mohammed; Benayas , Antonio; Marín , Riccardo; Natile , Marta María; Manso Silván, Miguel; Rubio Zuazo, Juan; Jaque, Daniel; Melle , Sonia; Gómez Calderón , Oscar; Rubio Retama , Jorge; Rubio Retama, Benito Jorge; Gómez Calderón, Óscar; Melle Hernández, Sonia; Zabala Gutiérrez, Irene; Torres Vera, Vivian Andrea
    Rare-earth doped nanoparticles (RENPs) are attracting increasing interest in materials science due to their optical, magnetic, and chemical properties. RENPs can emit and absorb radiation in the second biological window (NIR-II, 1000-1400 nm) making them ideal optical probes for photoluminescence (PL) in vivo imaging. Their narrow emission bands and long PL lifetimes enable autofluorescence-free multiplexed imaging. Furthermore, the strong temperature dependence of the PL properties of some of these RENPs makes remote thermal imaging possible. This is the case of neodymium and ytterbium co-doped NPs that have been used as thermal reporters for in vivo diagnosis of, for instance, inflammatory processes. However, the lack of knowledge about how the chemical composition and architecture of these NPs influence their thermal sensitivity impedes further optimization. To shed light on this, we have systematically studied their emission intensity, PL decay time curves, absolute PL quantum yield, and thermal sensitivity as a function of the core chemical composition and size, active-shell, and outer-inert-shell thicknesses. The results revealed the crucial contribution of each of these factors in optimizing the NP thermal sensitivity. An optimal active shell thickness of around 2 nm and an outer inert shell of 3.5 nm maximize the PL lifetime and the thermal response of the NPs due to the competition between the temperature-dependent back energy transfer, the surface quenching effects, and the confinement of active ions in a thin layer. These findings pave the way for a rational design of RENPs with optimal thermal sensitivity.