Suchergebnisse

A limiting factor of solvent‐induced nanoparticle self‐assembly is the need for constant sample dilution in assembly/disassembly cycles. Changes in the nanoparticle concentration alter the kinetics of the subsequent assembly process, limiting optical signal recovery. Herein, we show that upon confining hydrophobic nanoparticles in permeable silica nanocapsules, the number of nanoparticles participating in cyclic aggregation remains constant despite bulk changes in solution, leading to highly reproducible plasmon band shifts at different solvent compositions. ; L.M.L.-M. and M.G. acknowledge funding from the Spanish MINECO (Grant #MAT2013-46101R). N.C. and S.B. acknowledge financial support from European Research Council (ERC Starting Grant #335078-COLOURATOM). D.M.S., and J.M.T, acknowledge funding from the European Regional Development Fund (ERDF) and the Spanish MINECO (Projects TEC2017-85376-C2-1-R, TEC2017-85376-C2-2-R), and from the ERDF and the Galician Regional Government under agreement for funding the Atlantic Research Center for Information and Communication Technologies (AtlantTIC).

Colloidal anisotropic gold nanocrystals play a central role in the field of plasmonics owing to their tunable optical activity across a wide spectral range. However, achieving sufficient optical quality for practical implementation requires advanced synthetic protocols yielding gold nanocrystals with the desired morphology and plasmonic properties. This Minireview focuses on a fundamental step during the growth of anisotropic nanocrystals, namely symmetry breaking. In connection with thermodynamic and kinetic control of nanocrystal growth, we discuss the complex interplay between the role of seed morphology and that of surfactants, shape‐directing additives and reducing agents. We revisit some iconic syntheses of anisotropic gold nanoparticles, including nanorods, nanotriangles, and nanobipyramids. Finally, we analyze the use of co‐surfactants as an emerging strategy to disconnect the symmetry breaking event from the anisotropic growth process, overcoming current limitations in the synthesis of anisotropic gold nanocrystals. ; G. González‐Rubio gratefully acknowledges the Alexander von Humboldt Foundation for financial support. This work has been funded by the Spanish Ministry of Science, Innovation and Universities (grants RTI2018‐095844‐B‐I00, MAT2017‐86659‐R) and the Madrid Regional Government (grant P2018/NMT‐4389). This work was performed under the Maria de Maeztu Units of Excellence Program from the Spanish State Research Agency – Grant No. MDM‐2017‐0720. ; Peer reviewed

Magnetic hyperthermia (MHT) and photothermal therapy (PTT) are emergent state‐of‐the‐art modalities for thermal treatment of cancer. While their mechanisms of action have distinct physical bases, both approaches rely on nanoparticle‐mediated remote onset of thermotherapy. Yet, are the two heating techniques interchangeable? Here, the heating obtained either with MHT or with PTT is compared. The heating is assessed in distinct environments and involves a set of nanomaterials differing in shape (spheres, cubes, stars, shells, and rods) as well as in composition (maghemite, magnetite, cobalt ferrite, and gold). The nanoparticle's heating efficacy in an aqueous medium is first evaluated. Subsequently, the heating efficiency within the cellular environment, where intracellular processing markedly decreases MHT, is compared. Conversely, endosomal sequestration could have a positive effect on PTT. Finally, iron oxide nanocubes and gold nanostars are compared in MHT and PTT in vivo within the heterogeneous intratumoral environment. Overall, two distinct therapeutic approaches, related to high dosage allowing MHT and low dosage associated with PTT, are identified. It is also demonstrated that PTT mediated by magnetic nanoparticles has an efficacy that is comparable to that of plasmonic nanoparticles, but only at significant nanoparticle dosages. At low concentrations, only plasmonic nanoparticles can deliver a therapeutic heating. ; This work was supported by the European Union (Marie Curie Intra-European Project FP7-PEOPLE-2013-740 IEF-62647), by Paris city (Research in Paris), by CNRS and by Paris Diderot University. LML-M acknowledges funding from the Spanish MINECO (MAT2017-86659-R). The authors thank Ana Sánchez-Iglesias for the synthesis of Au nanostars, Christine Péchoux for TEM preparation and analysis, Karine Desboeufs for ICP measurements, Mathieu Receveur for conceiving the holder for NIR measurements, and Ludovic Maingault and Isabelle Le Parco from the animal housing facility at the Jacques Monod Institute ...

Gold nanostars display strong electromagnetic field enhancement at their tips, and tip plasmon resonances can be tuned within the visible and near-infrared, which has been applied toward plasmonic molecular sensing. However, the sensitivity can be further increased by linking gold nanostars to other plasmonic nanoparticles and thereby inducing the creation of hot spots. We report the controlled formation of core–satellite assemblies comprising a central gold nanostar with gold spheres adsorbed to the tips via Raman active molecular linkers. Surface-enhanced Raman scattering (SERS) was recorded at the level of single gold nanostar–satellite clusters, and the experimental results were compared with detailed electromagnetic simulations. ; L.M.L.-M. acknowledges funding from the European Research Council (ERC Advanced Grant #267867 PLASMAQUO) and the Spanish Ministerio de Economía y Competitividad (MAT2013-46101-R). D.M.S., J.M.T., and F.O. acknowledge funding from the European Regional Development Fund (ERDF) and the Spanish Government, Ministerio de Economía y Competitividad (TEC2011-28784-C02-01, TEC2011-28784-C02-02, CONSOLIDER INGENIO 2010 CSD2008-00068, project TACTICA), from the ERDF and the Galician Regional Government under agreement for funding the atlantic Research Center for Information and Communication Technologies (atlantTIC), and from the ERDF and the Extremadura Regional Government (IB13185).

The irradiation of gold nanorod colloids with a femtosecond laser can be tuned to induce controlled nanorod reshaping, yielding colloids with exceptionally narrow localized surface plasmon resonance bands. The process relies on a regime characterized by a gentle multishot reduction of the aspect ratio, whereas the rod shape and volume are barely affected. Successful reshaping can only occur within a narrow window of the heat dissipation rate: Low cooling rates lead to drastic morphological changes, and fast cooling has nearly no effect. Hence, a delicate balance must be achieved between irradiation fluence and surface density of the surfactant on the nanorods. This perfection process is appealing because it provides a simple, fast, reproducible, and scalable route toward gold nanorods with an optical response of exceptional quality, near the theoretical limit. ; This work was funded by the Spanish MINECO (Ministry of Economy and Competitiveness; grants CTQ2012-37404-C02-01, MAT2013-46101-R, MAT2014-59678-R, ENE2015-70300-C3-3-R, and CTQ2015-65033-P), the EUROfusion Consortium (AWP15-ENR-01/CEA-02), the Madrid Regional Government (S2013/MIT-2775 and S2013/MIT-2807), and the European Research Council (ERC Advanced Grant 267867, Plasmaquo). A.G.-M. and G.G.-R. respectively acknowledge receipt of Ramón y Cajal and FPI (Formación de Personal Investigador) fellowships from the Spanish MINECO. P.D.-N. acknowledges receipt of a fellowship from the Madrid Regional Government. The authors acknowledge the computer resources and technical assistance provided by CESVIMA (Centro de Supercomputación y Visualización de Madrid, Universidad Politécnica de Madrid) and the facilities provided by the Center for Ultrafast Lasers and the National Center of Microscopy (Universidad Complutense de Madrid). All results are reported in the main paper and supplementary materials.

When nanoparticles (NPs) are exposed to biological media, proteins are adsorbed, forming a so-called protein corona (PC). This cloud of protein aggregates hampers the targeting and transport capabilities of the NPs, thereby compromising their biomedical applications. Therefore, there is a high interest in the development of technologies that allow control over PC formation, as this would provide a handle to manipulate NPs in biological fluids. We present a strategy that enables the reversible disruption of the PC using external stimuli, thereby allowing a precise regulation of NP cellular uptake. The approach, demonstrated for gold nanoparticles (AuNPs), is based on a biorthogonal, supramolecular host–guest interactions between an anionic dye bound to the AuNP surface and a positively charged macromolecular cage. This supramolecular complex effectively behaves as a zwitterionic NP ligand, which is able not only to prevent PC formation but also to disrupt a previously formed hard corona. With this supramolecular stimulus, the cellular internalization of AuNPs can be enhanced by up to 30-fold in some cases, and even NP cellular uptake in phagocytic cells can be regulated. Additionally, we demonstrate that the conditional cell uptake of purposely designed gold nanorods can be used to selectively enhance photothermal cell death ; Funding was received from MINECO (SAF2016-76689-R, MAT2017-86659-R), Xunta de Galicia (2015-CP082, ED431C 2017/19, Centro singular de investigación de Galicia accreditation 2019-2022, ED431G 2019/03), the European Union (European Regional Development Fund), and the European Research Council (ERC AdG No. 787510 to L.M.L.-M.; ERC AdG No. 340055 to J.L.M). J.M. and M.M.-C. thank MINECO for Juan de la Cierva fellowships (FJCI-2015-25080 and IJCI-2014-19326). The proteomic analysis was performed in the proteomics platform at CIC bioGUNE, which is supported by Basque Department of Industry, Tourism and Trade (Etortek and Elkartek programs), the Innovation Technology Department of the Bizkaia ...

Perovskite nanocrystals (NCs) have revolutionized optoelectronic devices because of their versatile optical properties. However, controlling and extending these functionalities often requires a light management strategy involving additional processing steps. Here, we introduce a simple approach to shape perovskite nanocrystals (NC) into photonic architectures that provide light management by directly shaping the active material. Pre‐patterned polydimethylsiloxane (PDMS) templates are used for the template‐induced self‐assembly of 10 nm CsPbBr 3 perovskite NC colloids into large area (1 cm 2 ) 2D photonic crystals with tunable lattice spacing, ranging from 400 nm up to several microns. The photonic crystal arrangement facilitates efficient light coupling to the nanocrystal layer, thereby increasing the electric field intensity within the perovskite film. As a result, CsPbBr 3 2D photonic crystals show amplified spontaneous emission (ASE) under lower optical excitation fluences in the near‐IR, in contrast to equivalent flat NC films prepared using the same colloidal ink. This is attributed to the enhanced multi‐photon absorption caused by light trapping in the photonic crystal. ; D. Vila-Liarte and M. W. Feil have contributed equally to this work. We acknowledge financial support by the Bavarian State Ministry of Science, Research, and Arts through the grant "Solar Technologies go Hybrid (SolTech)". We thank local research clusters and centers such as CeNS for providing communicative networking structures. We also acknowledge support from the Spanish Ministerio de Ciencia e Innovación through Grants No. SEV-2015-0496 and MDM-2017-0720, in the framework of the Spanish Severo Ochoa and María de Maeztu Centers of Excellence program. This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (Grant Agreement No. 637116, ENLIGHTMENT). H.H acknowledges the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No. 839042. ; Peer reviewed