López Cabarcos, Enrique

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First Name
Last Name
López Cabarcos
Universidad Complutense de Madrid
Faculty / Institute
Química en Ciencias Farmacéuticas
Química Física
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Now showing 1 - 2 of 2
  • Publication
    Control of upconversion luminescence by gold nanoparticle size: from quenching to enhancement
    (RSC, 2019-08-07) Méndez González, Diego; Melle Hernández, Sonia; Gómez Calderón, Óscar; Laurenti, Marco; Cabrera Granado, Eduardo; Egatz-Gómez, Ana; López Cabarcos, Enrique; Rubio Retama, Jorge; Díaz García, Elena
    Metallic nanostructures have the potential to modify the anti-Stokes emission of upconverting nanoparticles (UCNPs) by coupling their plasmon resonance with either the excitation or the emission wavelength of the UCNPs. In this regard gold nanoparticles (AuNPs) have often been used in sensors for UCNP luminescence quenching or enhancement, although systematic studies are still needed in order to design optimal UCNP–AuNP based biosensors. Amidst mixed experimental evidence of quenching or enhancement, two key factors arise: the nanoparticle distance and nanoparticle size. In this work, we synthesize AuNPs of different sizes to assess their influence on the luminescence of UCNPs. We find that strong luminescence quenching due to resonance energy transfer is preferentially achieved for small AuNPs, peaking at an optimal size. A further increase in the AuNP size is accompanied by a reduction of luminescence quenching due to an incipient plasmonic enhancement effect. This enhancement counterbalances the luminescence quenching effect at the biggest tested AuNP size. The experimental findings are theoretically validated by studying the decay rate of the UCNP emitters near a gold nanoparticle using both a classical phenomenological model and the finite-difference time-domain method. Results from this study establish general guidelines to consider when designing sensors based on UCNPs–AuNPs as donor–quencher pairs, and suggest the potential of plasmon-induced luminescence enhancement as a sensing strategy.
  • Publication
    Ultrafast photochemistry produces superbright short-wave infrared dots for low-dose in vivo imaging
    (Nature Publishing Group, 2020-06-10) Santos, Harrison D. A.; Zabala Gutiérrez, Irene; Shen, Yingli; Lifante, José; Ximendes, Erving; Laurenti, Marco; Méndez González, Diego; Melle Hernández, Sonia; Gómez Calderón, Óscar; López Cabarcos, Enrique; Fernández Monsalve, Nuria; Chavez Coria, Irene; Lucena Agell, Daniel; Monge, Luis; Mackenzie, Mark D.; Marqués Hueso, José; Jones, Callum M. S.; Jacinto, Carlos; Rosal, Blanca, del; Kar, Ajoy K.; Rubio Retama, Jorge; Jaque García, Daniel
    Optical probes operating in the second near-infrared window (NIR-II, 1,000-1,700 nm), where tissues are highly transparent, have expanded the applicability of fluorescence in the biomedical field. NIR-II fluorescence enables deep-tissue imaging with micrometric resolution in animal models, but is limited by the low brightness of NIR-II probes, which prevents imaging at low excitation intensities and fluorophore concentrations. Here, we present a new generation of probes (Ag2S superdots) derived from chemically synthesized Ag2S dots, on which a protective shell is grown by femtosecond laser irradiation. This shell reduces the structural defects, causing an 80-fold enhancement of the quantum yield. PEGylated Ag2S superdots enable deep-tissue in vivo imaging at low excitation intensities (<10 mW cm−2) and doses (<0.5 mg kg−1), emerging as unrivaled contrast agents for NIR-II preclinical bioimaging. These results establish an approach for developing superbright NIR-II contrast agents based on the synergy between chemical synthesis and ultrafast laser processing.