Person: Guerrero Martínez, Andrés
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First Name
Andrés
Last Name
Guerrero Martínez
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Químicas
Department
Química Física
Area
Química Física
Identifiers
13 results
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Now showing 1 - 10 of 13
Item Supramolecular Control over the Interparticle Distance in Gold Nanoparticle Arrays by Cyclodextrin Polyrotaxanes(Nanomaterials, 2018) Coelho, Joao Paulo; Osío Barcina, José de Jesús; Junquera González, Elena; Aicart Sospedra, Emilio; Tardajos Rodríguez, Gloria; Gómez Graña, Sergio; Cruz Gil, Pablo; Salgado, Cástor; Díaz Núñez, Pablo; Peña Rodríguez, Ovidio; Guerrero Martínez, AndrésAmphiphilic nonionic ligands, synthesized with a fixed hydrophobic moiety formed by a thiolated alkyl chain and an aromatic ring, and with a hydrophilic tail composed of a variable number of oxyethylene units, were used to functionalize spherical gold nanoparticles (AuNPs) in water. Steady-state and time-resolved fluorescence measurements of the AuNPs in the presence of α-cyclodextrin (α-CD) revealed the formation of supramolecular complexes between the ligand and macrocycle at the surface of the nanocrystals. The addition of α-CD induced the formation of inclusion complexes with a high apparent binding constant that decreased with the increasing oxyethylene chain length. The formation of polyrotaxanes at the surface of AuNPs, in which many α-CDs are trapped as hosts on the long and linear ligands, was demonstrated by the formation of large and homogeneous arrays of self-assembled AuNPs with hexagonal close packing, where the interparticle distance increased with the length of the oxyethylene chain. The estimated number of α-CDs per polyrotaxane suggests a high rigidization of the ligand upon complexation, allowing for nearly perfect control of the interparticle distance in the arrays. This degree of supramolecular control was extended to arrays formed by AuNPs stabilized with polyethylene glycol and even to binary arrays. Electromagnetic simulations showed that the enhancement and distribution of the electric field can be finely controlled in these plasmonic arrays.- Project number: 52
Item I.amAble: El aprendizaje en ciencias al servicio de la inclusión educativa(2019) Herrero Domínguez, Santiago; Corrales Castellanos, María Eugenia; Sobrino Díaz, María Lourdes; Cilleros Prados, Olga; Barba Fernández, Carmen; Azor Lafarga, Alberto Eduardo; Hernández Díaz, María Yolanda; Martínez del Pozo, Álvaro; Ranchal Sánchez, Rocío; Maestre Varea, David; Méndez Pozo, Gonzalo Rubén; Gervás Gómez-Navarro, Pablo; Pastor Gil, Lorena; Taravillo Corralo, Mercedes; Guerrero Martínez, Andrés; Sánchez Benítez, Francisco Javier; Martín Conde, María; Priego Bermejo, José Luis; González Prieto, Rodrigo; Jiménez Aparicio, Reyes; Álvarez Serrano, Inmaculada; Cortés Gil, Raquel; Osío Barcina, José de Jesús; Mancheño Real, María José; Arribas Fernández, Paula; Lobato Fernández, Álvaro; Sánchez Arroyo, Antonio José; Torrecilla Manresa, Sofía; Cárdenas Bonett, Marlón Félix; Desvoyes, Benedicte; Bárcena Espelleta, Araceli; Nacenta Torres, Pablo; Rubio Lago, Luis; Bautista Blasco, Susana; Julián Cortés, Alvaro; Arancibia Llaneza, Julieta Noelia; Lombraña Pascual, Rodrigo; Catalán Torrecilla, Cristina; Gutiérrez Franco, Yanna María; Mártínez Ruiz, María PalomaI.amAble es un proyecto que nació con una filosofía centrada en la utilización de acciones de solidaridad como método de aprendizaje. Se diseñan y organizan talleres científicos inclusivos para realizarlos en parejas formadas por personas con discapacidad cognitiva y de educación secundaria ordinaria. Se pretende aprender a la vez que se da un servicio a la universidad y a la sociedad, y ese es el espíritu que se ha seguido manteniendo durante esta tercera edición del curso 2018-2019. Item Facile Strategy for the Synthesis of Gold@Silica Hybrid Nanoparticles with Controlled Porosity and Janus Morphology(Nanomaterials, 2019) Santana Vega, Marina; Guerrero Martínez, Andrés; Cucinotta, FabioHybrid materials prepared by encapsulation of plasmonic nanoparticles in porous silica systems are of increasing interest due to their high chemical stability and applications in optics, catalysis and biological sensing. Particularly promising is the possibility of obtaining gold@silica nanoparticles (Au@SiO2 NPs) with Janus morphology, as the induced anisotropy can be further exploited to achieve selectivity and directionality in physical interactions and chemical reactivity. However, current methods to realise such systems rely on the use of complex procedures based on binary solvent mixtures and varying concentrations of precursors and reaction conditions, with reproducibility limited to specific Au@SiO2 NP types. Here, we report a simple one-pot protocol leading to controlled crystallinity, pore order, monodispersity, and position of gold nanoparticles (AuNPs) within mesoporous silica by the simple addition of a small amount of sodium silicate. Using a fully water-based strategy and constant content of synthetic precursors, cetyl trimethylammonium bromide (CTAB) and tetraethyl orthosilicate (TEOS), we prepared a series of four silica systems: (A) without added silicate, (B) with added silicate, (C) with AuNPs and without added silicate, and (D) with AuNPs and with added silicate. The obtained samples were characterised by transmission electron microscopy (TEM), small angle X-ray scattering (SAXS), and UV-visible spectroscopy, and kinetic studies were carried out by monitoring the growth of the silica samples at different stages of the reaction: 1, 10, 15, 30 and 120 min. The analysis shows that the addition of sodium silicate in system B induces slower MCM-41 nanoparticle (MCM-41 NP) growth, with consequent higher crystallinity and better-defined hexagonal columnar porosity than those in system A. When the synthesis was carried out in the presence of CTAB-capped AuNPs, two different outcomes were obtained: without added silicate, isotropic mesoporous silica with AuNPs located at the centre and radial pore order (C), whereas the addition of silicate produced Janus-type Au@SiO2 NPs (D) in the form of MCM-41 and AuNPs positioned at the silica–water interface. Our method was nicely reproducible with gold nanospheres of different sizes (10, 30, and 68 nm diameter) and gold nanorods (55 × 19 nm), proving to be the simplest and most versatile method to date for the realisation of Janus-type systems based on MCM-41-coated plasmonic nanoparticles.Item A Non-Viral Plasmid DNA Delivery System Consisting on a Lysine-Derived Cationic Lipid Mixed with a Fusogenic Lipid(Pharmaceutics, 2019) Martínez Negro, María; Sánchez Arribas, Natalia; Guerrero Martínez, Andrés; Moyá, María Luisa; Tros de Ilarduya, Conchita; Mendicuti, Francisco; Aicart Sospedra, Emilio; Junquera González, ElenaThe insertion of biocompatible amino acid moieties in non-viral gene nanocarriers is an attractive approach that has been recently gaining interest. In this work, a cationic lipid, consisting of a lysine-derived moiety linked to a C12 chain (LYCl) was combined with a common fusogenic helper lipid (DOPE) and evaluated as a potential vehicle to transfect two plasmid DNAs (encoding green fluorescent protein GFP and luciferase) into COS-7 cells. A multidisciplinary approach has been followed: (i) biophysical characterization based on zeta potential, gel electrophoresis, small-angle X-ray scattering (SAXS), and cryo-transmission electronic microscopy (cryo-TEM); (ii) biological studies by fluorescence assisted cell sorting (FACS), luminometry, and cytotoxicity experiments; and (iii) a computational study of the formation of lipid bilayers and their subsequent stabilization with DNA. The results indicate that LYCl/DOPE nanocarriers are capable of compacting the pDNAs and protecting them efficiently against DNase I degradation, by forming Lα lyotropic liquid crystal phases, with an average size of ~200 nm and low polydispersity that facilitate the cellular uptake process. The computational results confirmed that the LYCl/DOPE lipid bilayers are stable and also capable of stabilizing DNA fragments via lipoplex formation, with dimensions consistent with experimental values. The optimum formulations (found at 20% of LYCl content) were able to complete the transfection process efficiently and with high cell viabilities, even improving the outcomes of the positive control Lipo2000*.Item Effect of Organic Stabilizers on Silver Nanoparticles Fabricated by Femtosecond Pulsed Laser Ablation(Applied Sciences, 2017) Díaz Núñez, Pablo; González Izquierdo, Jesús; González Rubio, Guillermo; Guerrero Martínez, Andrés; Rivera, Antonio; Perlado, José; Bañares Morcillo, Luis; Peña-Rodríguez, OvidioLaser ablation has several advantages over the chemical synthesis of nanoparticles due to its simplicity and because it is a faster and cleaner process. In this paper, we use femtosecond laser ablation to generate highly concentrated silver colloidal nanoparticle solutions. Those high concentrations usually lead to agglomeration of the nanoparticles, rendering the solution nearly useless. We employ two different organic stabilizers (hexadecyltrimethylammonium bromide, CTAB, and polyvinylpyrrolidone, PVP) to avoid this problem and study their effect on the nanoparticle size distribution, structural characteristics, and the solution concentration.Item Nanocapillarity and the liquid bridge mediated force between colloidal nanoparticles(ACS Omega, 2018) MacDowell, Luis G.; Llombart, Pablo; Benet, Jorge; Palanco, Jose; Guerrero Martínez, AndrésIn this work we probe the concept of interface tension for ultra thin adsorbed liquid films in the nanoscale by studying the surface fluctuations of films down to the monolayer. Our results show that the spectrum of film height fluctuations of a liquid-vapor surface may be extended to ultra thin films provided we take into account the interactions of the substrate with the surface. Global fluctuations of film height are described in terms of the disjoining pressure, while surface deformations that are proportional to the interface area are accounted for by a film thick dependent surface tension. As a prove of concept, we model the capillary forces between colloidal nanoparticles held together by liquid bridges. Our results indicate that the classical equations for capillarity follow very precisely down to the nanoscale, provided we account for the film height dependence of the surface tension.Item Intracellular pH-Induced Tip-to-Tip Assembly of Gold Nanorods for Enhanced Plasmonic Photothermal Therapy(ACS Omega, 2016) Ahijado Guzmán, Rubén; Bañares Morcillo, Luis; Guerrero Martínez, Andrés; López Montero, Iván; Tardajos Rodríguez, Gloria María; González Rubio, Guillermo; Izquierdo, Jesús G.; Calzado Martín, Alicia; Calleja, MontserratThe search for efficient plasmonic photothermal therapies using nonharmful pulse laser irradiation at the near-infrared (NIR) is fundamental for biomedical cancer research. Therefore, the development of novel assembled plasmonic gold nanostructures with the aim of reducing the applied laser power density to a minimum through hot-spot-mediated cell photothermolysis is an ongoing challenge. We demonstrate that gold nanorods (Au NRs) functionalized at their tips with a pH-sensitive ligand assemble into oligomers within cell lysosomes through hydrogen-bonding attractive interactions. The unique intracellular features of the plasmonic oligomers allow us to significantly reduce the femtosecond laser power density and Au NR dose while still achieving excellent cell killing rates. The formation of gold tip-to-tip oligomers with longitudinal localized surface plasmon resonance bands at the NIR, obtained from low-aspect-ratio Au NRs close in resonance with 800 nm Ti:sapphire 90 fs laser pulses, was found to be the key parameter for realizing the enhanced plasmonic photothermal therapy.Item pH-triggered endosomal escape of pore-forming Listeriolysin O toxin-coated gold nanoparticles(Journal of Nanobiotechnology, 2019) Plaza-GA, Ismael; Manzaneda González, Vanesa; Kisovec, Matic; Almendro Vedia, Víctor Galileo; Muñoz Úbeda, Mónica; Anderluh, Gregor; Guerrero Martínez, Andrés; Natale, Paolo; López-Montero, IvánBackground: A major bottleneck in drug delivery is the breakdown and degradation of the delivery system through the endosomal/lysosomal network of the host cell, hampering the correct delivery of the drug of interest. In nature, the bacterial pathogen Listeria monocytogenes has developed a strategy to secrete Listeriolysin O (LLO) toxin as a tool to escape the eukaryotic lysosomal system upon infection, allowing it to grow and proliferate unharmed inside the host cell. Results: As a “proof of concept”, we present here the use of purifed His-LLO H311A mutant protein and its conjuga tion on the surface of gold nanoparticles to promote the lysosomal escape of 40 nm-sized nanoparticles in mouse embryonic fbroblasts. Surface immobilization of LLO was achieved after specifc functionalization of the nanoparti cles with nitrile acetic acid, enabling the specifc binding of histidine-tagged proteins. Conclusions: Endosomal acidifcation leads to release of the LLO protein from the nanoparticle surface and its self-assembly into a 300 Å pore that perforates the endosomal/lysosomal membrane, enabling the escape of nanoparticles.Item Mechanosensitive Gold Colloidal Membranes Mediated by Supramolecular Interfacial Self-Assembly(Journal of the American Chemical Society, 2017) Coelho, João Paulo; Mayoral, María José; Camacho, Luis; Martín-Romero, María T.; Tardajos Rodríguez, Gloria; López-Montero, Iván; Sanz García, Eduardo; Ávila Brande, David; Giner-Casares, Juan José; Fernández, Gustavo; Guerrero Martínez, AndrésThe ability to respond toward mechanical stimuli is a fundamental property of biological organisms at both the macroscopic and cellular levels, yet it has been considerably less observed in artificial supramolecular and colloidal homologues. An archetypal example in this regard is cellular mechanosensation, a process by which mechanical forces applied on the cell membrane are converted into biochemical or electrical signals through nanometer-scale changes in molecular conformations. In this article, we report an artificial gold nanoparticle (Au NP)−discrete π-conjugated molecule hybrid system that mimics the mechanical behavior of biological membranes and is able to self-assemble into colloidal gold nanoclusters or membranes in a controlled and reversible fashion by changing the concentration or the mechanical force (pressure) applied. This has been achieved by rational design of a small π-conjugated thiolated molecule that controls, to a great extent, the hierarchy levels involved in Au NP clustering by enabling reversible, cooperative non-covalent (π−π, solvophobic, and hydrogen bonding) interactions. In addition, the Au NP membranes have the ability to entrap and release aromatic guest molecules reversibly (Kb = 5.0 × 105 M−1 ) for several cycles when subjected to compression−expansion experiments, in close analogy to the behavior of cellular mechanosensitive channels. Not only does our hybrid system represent the first example of a reversible colloidal membrane, but it also can be controlled by a dynamic mechanical stimulus using a new supramolecular surface-pressure-controlled strategy. This approach holds great potential for the development of multiple colloidal assemblies within different research fields.Item Supramolecular zippers elicit interbilayer adhesion of membranes producing cell death(Biochimica et Biophysica Acta (BBA) - General Subjects, 2018) Almendro Vedia, Víctor Galileo; García, Carolina; Ahijado Guzmán, Rubén; de la Fuente Herreruela, Diego; Muñoz Úbeda, Mónica; Natale, Paolo; Viñas, Montserrat H.; Albuquerque, Rodrigo Queiroz; Guerrero Martínez, Andrés; Monroy, Francisco; Lillo, M. Pilar; López-Montero, IvánBackground: The fluorescent dye 10-N-nonyl acridine orange (NAO) is widely used as a mitochondrial marker. NAO was reported to have cytotoxic effects in cultured eukaryotic cells when incubated at high concentrations. Although the biochemical response of NAO-induced toxicity has been well identified, the underlying molecular mechanism has not yet been explored in detail. Methods: We use optical techniques, including fluorescence confocal microscopy and lifetime imaging microscopy (FLIM) both in model membranes built up as giant unilamellar vesicles (GUVs) and cultured cells. These experiments are complemented with computational studies to unravel the molecular mechanism that makes NAO cytotoxic. Results: We have obtained direct evidence that NAO promotes strong membrane adhesion of negatively charged vesicles. The attractive forces are derived from van der Waals interactions between anti-parallel H-dimers of NAO molecules from opposing bilayers. Semi-empirical calculations have confirmed the supramolecular scenario by which anti-parallel NAO molecules form a zipper of bonds at the contact region. The membrane remodeling effect of NAO, as well as the formation of H-dimers, was also confirmed in cultured fibroblasts, as shown by the ultrastructure alteration of the mitochondrial cristae. Conclusions: We conclude that membrane adhesion induced by NAO stacking accounts for the supramolecular basis of its cytotoxicity. General significance: Mitochondria are a potential target for cancer and gene therapies. The alteration of the mitochondrial structure by membrane remodeling agents able to form supramolecular assemblies via adhesion properties could be envisaged as a new therapeutic strategy.