Suchergebnisse

Understanding protein amyloidogenesis is an important topic in protein science, fueled by the role of amyloid aggregates, especially oligomers, in the etiology of a number of devastating human degenerative diseases. However, the mechanisms that determine the formation of amyloid oligomers remain elusive due to the high complexity of the amyloidogenesis process. For instance, gold nanoparticles promote or inhibit amyloid fibrillation. We have functionalized gold nanorods with a metal-chelating group to selectively immobilize soluble RepA-WH1, a model synthetic bacterial prionoid, using a hexa-histidine tag (H6). H6-RepA-WH1 undergoes stable amyloid oligomerization in the presence of catalytic concentrations of anisotropic nanoparticles. Then, in a physically separated event, such oligomers promote the growth of amyloid fibers of untagged RepA-WH1. SERS spectral changes of H6-RepA-WH1 on spherical citrate-AuNP substrates provide evidence for structural modifications in the protein, which are compatible with a gradual increase in ?-sheet structure, as expected in amyloid oligomerization. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim ; Research at RG laboratory was supported by MINECO grants CSD2009-00088 and BIO2012-30852. Research at AGM and LMLM laboratories was supported by MINECO (MAT2014-59678-R and MAT2013-46101-R) and Madrid Regional Government (S2013/MIT-2807) grants. A.G.-M. and G.G.-R., respectively, acknowledge receipt of Ramón y Cajal and FPI Fellowships from the Spanish MINECO.

We experimentally and theoretically investigate the interactions between localized plasmons in gold nanorods and excitons in J-aggregates under ambient conditions. Thanks to our sample preparation procedure we are able to track a clear anticrossing behavior of the hybridized modes not only in the extinction but also in the photoluminescence (PL) spectra of this hybrid system. Notably, while previous studies often found the PL signal to be dominated by a single mode (emission from so-called lower polariton branch), here we follow the evolution of the two PL peaks as the plasmon energy is detuned from the excitonic resonance. Both the extinction and PL results are in good agreement with the theoretical predictions obtained for a model that assumes two interacting modes with a ratio between the coupling strength and the plasmonic losses close to 0.4, indicative of the strong coupling regime with a significant Rabi splitting estimated to be ?200 meV. The evolution of the PL line shape as the plasmon is detuned depends on the illumination wavelength, which we attribute to an incoherent excitation given by decay processes in either the metallic rods or the J-aggregates. © 2016 American Chemical Society. ; We acknowledge financial support from Project FIS2013-41184-P of the Spanish Ministry of Economy and Competitiveness (MINECO). R. E. acknowledges funding as Fellow Gipuzkoa of the Gipuzkoako Foru Aldundia through Feder Funds of the European Union "Una manera de hacer Europa".

[EN] Gated mesoporous silica nanoparticles can deliver payload upon the application of a predefined stimulus, and therefore are promising drug delivery systems. Despite their important role, relatively low emphasis has been placed on the design of gating systems that actively target carbohydrate tumor cell membrane receptors. We describe herein a new Lewis X (Le(x)) antigen-targeted delivery system comprising mesoporous silica nanoparticles (MSNs) loaded with ATTO 430LS dye, functionalized with a Le(x) derivative (1) and capped with a fucose-specific carbohydrate-binding protein (Aleuria aurantia lectin (AAL)). This design takes advantage of the affinity of AAL for Le(x) overexpressed receptors in certain cancer cells. In the proximity of the cells, AAL is detached from MSNs to bind Le(x), and selectins in the cells bind Le(x) in the gated MSNs, thereby inducing cargo delivery. Gated MSNs are nontoxic to colon cancer DLD-1 cells, and ATTO 430LS dye delivered correlated with the amount of Le(x) antigen overexpressed at the DLD-1 cell surface. This is one of the few examples of MSNs using biologically relevant glycans for both capping (via interaction with AAL) and targeting (via interaction with overexpressed Le(x) at the cell membrane). ; The authors thank the Spanish Government (Projects MAT2015-64139-C4-1-R and MAT2013-46101-R (MINECO/ FEDER)), Fondo de Investigacion Sanitaria (PI15/00480) and Generalitat Valenciana (Project PROMETEOII/2014/047 and project GVA/2014/13) for support. R. B. is thankful to Svagata. Eu (Erasmus Mundus Action-II program) for his fellowship. The authors also thank the Electron Microscopy Service at the UPV for support. ; Bhat, R.; García, I.; Aznar, E.; Arnáiz, B.; Martínez-Bisbal, M.; Liz-Marzán, L.; Penadés, S. (2018). Lectin-gated and glycan functionalized mesoporous silica nanocontainers for targeting cancer cells overexpressing Lewis X antigen. Nanoscale. 10(1):239-249. https://doi.org/10.1039/c7nr06415b ; S ; 239 ; 249 ; 10 ; 1 ; Argyo, C., Weiss, V., Bräuchle, C., & Bein, ...