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  • 1.
    Bano, Fouzia
    et al.
    University of Liège, Department of Chemistry, Belgium.
    Sluysmans, D.
    Wislez, A.
    Duwez, A. -S
    Unraveling the complexity of the interactions of DNA nucleotides with gold by single molecule force spectroscopy2015In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 7, no 46, p. 19528-19533Article in journal (Refereed)
    Abstract [en]

    Addressing the effect of different environmental factors on the adsorption of DNA to solid supports is critical for the development of robust miniaturized devices for applications ranging from biosensors to next generation molecular technology. Most of the time, thiol-based chemistry is used to anchor DNA on gold – a substrate commonly used in nanotechnology – and little is known about the direct interaction between DNA and gold. So far there have been no systematic studies on the direct adsorption behavior of the deoxyribonucleotides (i.e., a nitrogenous base, a deoxyribose sugar, and a phosphate group) and on the factors that govern the DNA–gold bond strength. Here, using single molecule force spectroscopy, we investigated the interaction of the four individual nucleotides, adenine, guanine, cytosine, and thymine, with gold. Experiments were performed in three salinity conditions and two surface dwell times to reveal the factors that influence nucleotide–Au bond strength. Force data show that, at physiological ionic strength, adenine–Au interactions are stronger, asymmetrical and independent of surface dwell time as compared to cytosine–Au and guanine–Au interactions. We suggest that in these conditions only adenine is able to chemisorb on gold. A decrease of the ionic strength significantly increases the bond strength for all nucleotides. We show that moderate ionic strength along with longer surface dwell period suggest weak chemisorption also for cytosine and guanine.

  • 2. Bosco, Alessandro
    et al.
    Bano, Fouzia
    Scuola Internazionale Superiore di Studi Avanzati (SISSA), Trieste, Italy; NanoChemistry and Molecular Systems Department of Chemistry, University of Liège,Liège, Belgium.
    Parisse, Pietro
    Casalis, Loredana
    DeSimone, Antonio
    Micheletti, Cristian
    Hybridization in nanostructured DNA monolayers probed by AFM: theory versus experiment2012In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 4, no 5, p. 1734-1741Article in journal (Refereed)
    Abstract [en]

    Nanografted monolayers (NAMs) of DNA show novel physico-chemical properties that make them ideally suited for advanced biosensing applications. In comparison with alternative solid-phase techniques for diagnostic DNA detection, NAMs have the advantage of combining a small size with a high homogeneity of the DNA surface coverage. These two properties favour the extreme miniaturization and ultrasensitivity in high-throughput biosensing devices. The systematic use of NAMs for quantitative DNA (and protein) detection has so far suffered from the lack of a control on key fabrication parameters, such as the ss- or ds-DNA surface coverage. Here we report on a combined experimental–computational study that allows us to estimate the surface density of the grafted DNA by analyzing the sample mechanical response, that is the DNA patch height vs. applied tip load curves. It is shown that the same analysis scheme can be used to detect the occurrence of hybridization with complementary strands in solution and estimate its efficiency. Thanks to these quantitative relationships it is possible to use a single AFM-based setup to: (i) fabricate a DNA NAM, (ii) control the DNA surface coverage, and (iii) characterize its level of hybridization helping the design of NAMs with pre-determined fabrication parameters.

  • 3.
    Boulanger, Nicolas
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Yu, Junchun
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Barbero, David
    Umeå University, Faculty of Science and Technology, Department of Physics.
    SWNT nano-engineered networks strongly increase charge transport in P3HT2014In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 6, no 20, p. 11633-11636Article in journal (Refereed)
    Abstract [en]

    We demonstrate the formation of arrays of 3D nano- sized networks of interconnected single-wall carbon nanotubes (SWNT) with well defined dimensions in a poly-3- hexylthiophene (P3HT) thin film. These novel nanotube nano-networks produce efficient ohmic charge transport, even at very low nanotube loadings and low voltages. An increase in conductivity between one and two orders of magnitude is observed compared to a random network. The formation of these nano-engineered networks is compatible with large area imprinting and roll to roll processes, which makes it highly desirable for opto-electronic and energy conversion applications using carbon nanotubes.

  • 4.
    Chen, Xi
    et al.
    Optics and Photonics, School of Information and Communication Technology, KTH Royal Institute of Technology, Kista, Sweden.
    Chen, Yiting
    Optics and Photonics, School of Information and Communication Technology, KTH Royal Institute of Technology, Kista, Sweden.
    Dai, Jin
    Optics and Photonics, School of Information and Communication Technology, KTH Royal Institute of Technology, Kista, Sweden.
    Yan, Min
    Optics and Photonics, School of Information and Communication Technology, KTH Royal Institute of Technology, Kista, Sweden.
    Zhao, Ding
    State Key Laboratory of Modern Optical Instrumentation, Department of Optical Engineering, Zhejiang University, Hangzhou, China.
    Li, Qiang
    State Key Laboratory of Modern Optical Instrumentation, Department of Optical Engineering, Zhejiang University, Hangzhou, China.
    Qiu, Min
    State Key Laboratory of Modern Optical Instrumentation, Department of Optical Engineering, Zhejiang University, Hangzhou, China; Optics and Photonics, School of Information and Communication Technology, KTH Royal Institute of Technology, Kista, Sweden.
    Ordered Au nanocrystals on a substrate formed by light-induced rapid annealing2014In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 6, no 3, p. 1756-1762Article in journal (Refereed)
    Abstract [en]

    Light-induced rapid annealing (LIRA) is a widely used method to modify the morphology and crystallinity of noble metal nanoparticles, and the nanoparticles generally evolve into nanospheres. It is rather challenging to form faceted Au nanocrystals on a substrate using LIRA. Here the formation of spatially ordered Au nanocrystals using a continuous wave infrared laser is reported, assisted by a metamaterial perfect absorber. Faceted Au nanocrystals in truncated-octahedral or multi-twinned geometries can be obtained. The evolution of morphology and crystallinity of the Au nanoparticles during laser annealing is also revealed, where the crystal grain growth and the surface melting are shown to play key roles in nanocrystal formation. The evolution of morphology also gives the freedom of tuning the absorption spectrum of the metamaterial absorber. These findings provide a novel way for tailoring the morphology and crystallinity of metallic nanoparticles and may pave the way to fabricate refined nano-devices in many potential applications for optics, electronics, catalysis, surface-chemistry and biology.

  • 5.
    Deiana, Marco
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Chand, Karam
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Jamroskovic, Jan
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Das, Rabindra Nath
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Obi, Ikenna
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Chorell, Erik
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Sabouri, Nasim
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    A Site-Specific Self-Assembled Light-up Rotor Probe for Selective Recognition and Stabilization of c-MYC G-Quadruplex DNA2020In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 12, no 24, p. 12950-12957Article in journal (Refereed)
    Abstract [en]

    Direct and unambiguous evidence of the formation of G-quadruplexes (G4s) in human cells have shown their implication in several key biological events and has emphasized their role as important targets for small-molecule cancer therapeutics. Here, we report on the first example of a self-assembled multitasking molecular-rotor G4-binder able to discriminate between an extensive panel of G4 and non-G4 structures and to selectively light-up (up to 105-fold), bind (nanomolar range), and stabilize the c-MYC promoter G4 DNA. In particular, association with the c-MYC G4 triggers the disassembly of its supramolecular state (disaggregation-induced emission, DIE) and induces geometrical restrictions (motion-induced change in emission, MICE) leading to a significant enhancement of its emission yield. Moreover, this optical reporter is able to selectively stabilize the c-MYC G4 and inhibit DNA synthesis. Finally, by using confocal laser-scanning microscopy (CLSM) we show the ability of this compound to localize primarily in the subnuclear G4-rich compartments of cancer cells. This work provides a benchmark for the future design and development of a new generation of smart sequence-selective supramolecular G4-binders that combine outstanding sensing and stability properties, to be utilized in anti-cancer therapy.

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  • 6.
    Deiana, Marco
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Mosser, Maëlle
    Le Bahers, Tangui
    Dumont, Elise
    Dudek, Marta
    Denis-Quanquin, Sandrine
    Sabouri, Nasim
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Andraud, Chantal
    Matczyszyn, Katarzyna
    Monnereau, Cyrille
    Guy, Laure
    Light-induced in situ chemical activation of a fluorescent probe for monitoring intracellular G-quadruplex structures2021In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 13, no 32, p. 13795-13808Article in journal (Refereed)
    Abstract [en]

    Light-activated functional materials capable of remote control over duplex and G-quadruplex (G4) nucleic acids formation at the cellular level are still very rare. Herein, we report on the photoinduced macrocyclisation of a helicenoid quinoline derivative of binaphthol that selectively provides easy access to an unprecedented class of extended heteroaromatic structures with remarkable photophysical and DNA/RNA binding properties. Thus, while the native bisquinoline precursor shows no DNA binding activity, the new in situ photochemically generated probe features high association constants to DNA and RNA G4s. The latter inhibits DNA synthesis by selectively stabilizing G4 structures associated with oncogenic promoters and telomere repeat units. Finally, the light sensitive compound is capable of in cellulo photoconversion, localizes primarily in the G4-rich sites of cancer cells, competes with a well-known G4 binder and shows a clear nuclear co-localization with the quadruplex specific antibody BG4. This work provides a benchmark for the future design and development of a brand-new generation of light-activated target-selective G4-binders.

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  • 7.
    Garoli, Denis
    et al.
    Istituto Italiano di Tecnologia, Genova, Italy.
    Mosconi, Dario
    Dipartimento di Chimica, Università degli Studi di Padova, Padova, Italy.
    Miele, Ermanno
    Istituto Italiano di Tecnologia, Genova, Italy.
    Maccaferri, Nicolò
    Istituto Italiano di Tecnologia, Genova, Italy.
    Ardini, Matteo
    Istituto Italiano di Tecnologia, Genova, Italy.
    Giovannini, Giorgia
    Istituto Italiano di Tecnologia, Genova, Italy.
    Dipalo, Michele
    Istituto Italiano di Tecnologia, Genova, Italy.
    Agnoli, Stefano
    Dipartimento di Chimica, Università degli Studi di Padova, Padova, Italy.
    De Angelis, Francesco
    Istituto Italiano di Tecnologia, Genova, Italy.
    Hybrid plasmonic nanostructures based on controlled integration of MoS2 flakes on metallic nanoholes2018In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 10, no 36, p. 17105-17111Article in journal (Refereed)
    Abstract [en]

    Here, we propose an easy and robust strategy for the versatile preparation of hybrid plasmonic nanopores by means of controlled deposition of single flakes of MoS2 directly on top of metallic holes. The device is realized on silicon nitride membranes and can be further refined by TEM or FIB milling to achieve the passing of molecules or nanometric particles through a pore. Importantly, we show that the plasmonic enhancement provided by the nanohole is strongly accumulated in the 2D nanopore, thus representing an ideal system for single-molecule sensing and sequencing in a flow-through configuration. Here, we also demonstrate that the prepared 2D material can be decorated with metallic nanoparticles that can couple their resonance with the nanopore resonance to further enhance the electromagnetic field confinement at the nanoscale level. This method can be applied to any gold nanopore with a high level of reproducibility and parallelization; hence, it can pave the way to the next generation of solid-state nanopores with plasmonic functionalities. Moreover, the controlled/ordered integration of 2D materials on plasmonic nanostructures opens a pathway towards new investigation of the following: enhanced light emission; strong coupling from plasmonic hybrid structures; hot electron generation; and sensors in general based on 2D materials.

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  • 8.
    Iakunkov, Artem
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Nordenström, Andreas
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Boulanger, Nicolas
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Hennig, Christoph
    Institute of Resource Ecology, Helmholtz Zentrum Dresden Rossendorf, Dresden, Germany; The Rossendorf Beamline, European Synchrotron Radiation Facility, Grenoble, France.
    Baburin, Igor
    Theoretische Chemie, Technische Universität Dresden, Dresden, Germany.
    Talyzin, Aleksandr V.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Temperature-dependent swelling transitions in MXene Ti3C2Tx2022In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 14, no 30, p. 10940-10949Article in journal (Refereed)
    Abstract [en]

    Swelling is a property of hydrophilic layered materials, which enables the penetration of polar solvents into an interlayer space with expansion of the lattice. Here we report an irreversible swelling transition, which occurs in MXenes immersed in excess dimethyl sulfoxide (DMSO) upon heating at 362-370 K with an increase in the interlayer distance by 4.2 Å. The temperature dependence of MXene Ti3C2Tx swelling in several polar solvents was studied using synchrotron radiation X-ray diffraction. MXenes immersed in excess DMSO showed a step-like increase in the interlayer distance from 17.73 Å at 280 K to 22.34 Å above ∼362 K. The phase transformation corresponds to a transition from the MXene structure with one intercalated DMSO layer into a two-layer solvate phase. The transformation is irreversible and the expanded phase remains after cooling back to room temperature. A similar phase transformation was observed also for MXene immersed in a 2 : 1 H2O : DMSO solvent ratio but at a lower temperature. The structure of MXene in the mixed solvent below 328 K was affected by the interstratification of differently hydrated (H2O)/solvated (DMSO) layers. Above the temperature of the transformation, the water was expelled from MXene interlayers and the formation of a pure two-layer DMSO-MXene phase was found. No changes in the swelling state were observed for MXenes immersed in DMSO or methanol at temperatures below ambient down to 173 K. Notably, MXenes do not swell in 1-alcohols larger than ethanol at ambient temperature. Changing the interlayer distance of MXenes by simple temperature cycling can be useful in membrane applications, e.g. when a larger interlayer distance is required for the penetration of ions and molecules into membranes. Swelling is also very important in electrode materials since it allows penetration of the electrolyte ions into the interlayers of the MXene structure.

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  • 9.
    Iakunkov, Artem
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Talyzin, Aleksandr V.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Swelling properties of graphite oxides and graphene oxide multilayered materials2020In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 12, no 41, p. 21060-21093Article, review/survey (Refereed)
    Abstract [en]

    Graphite oxide (GtO) and graphene oxide (GO) multilayered laminates are hydrophilic materials easily intercalated by water and other polar solvents. By definition, an increase in the volume of a material connected to the uptake of a liquid or vapour is named swelling. Swelling is a property which defines graphite oxides and graphene oxides. Less oxidized materials not capable of swelling should be named oxidized graphene. The infinite swelling of graphite oxide yields graphene oxide in aqueous dispersions. Graphene oxide sheets dispersed in a polar solvent can be re-assembled into multilayered structures and named depending on applications as films, papers or membranes. The multilayered GO materials exhibit swelling properties which are mostly similar to those of graphite oxides but not identical and in some cases surprisingly different. Swelling is a key property of GO materials in all applications which involve the sorption of water/solvents from vapours, immersion of GO into liquid water/solvents and solution based chemical reactions. These applications include sensors, sorption/removal of pollutants from waste waters, separation of liquid and gas mixtures, nanofiltration, water desalination, water-permeable protective coatings, etc. Swelling defines the distance between graphene oxide sheets in solution-immersed GO materials and the possibility for penetration of ions and molecules inside of interlayers. A high sorption capacity of GO towards many molecules and cations is defined by swelling which makes the very high surface area of GO accessible. GtO and GO swelling is a surprisingly complex phenomenon which is manifested in a variety of different ways. Swelling is strongly different for materials produced using the most common Brodie and Hummers oxidation procedures; it depends on the degree of oxidation, ad temperature and pressure conditions. The value of the GO interlayer distance is especially important in membrane applications. Diffusion of solvent molecules and ions is defined by the size of "permeation channels" provided by the swelled GO structure. According to extensive studies performed over the last decade the exact value of the inter-layer distance in swelled GO depends on the nature of solvent, temperature and pressure conditions, and the pH and concentration of solutions and exhibits pronounced aging effects. This review provides insight into the fundamental swelling properties of multilayered GO and demonstrates links to advanced applications of these materials.

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  • 10.
    Klechikov, Alexey
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Sun, Jinhua
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Baburin, Igor A.
    Seifert, Gotthard
    Rebrikova, Anastasiia T.
    Avramenko, Natalya V.
    Korobov, Mikhail V.
    Talyzin, Alexandr V.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Multilayered intercalation of 1-octanol into Brodie graphite oxide2017In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 9, no 20, p. 6929-6936Article in journal (Refereed)
    Abstract [en]

    Multilayered intercalation of 1-octanol into the structure of Brodie graphite oxide (B-GO) was studied as a function of temperature and pressure. Reversible phase transition with the addition/removal of one layer of 1-octanol was found at 265 K by means of X-ray Diffraction (XRD) and Differential Scanning Calorimetry (DSC). The same transition was observed at ambient temperature upon a pressure increase above 0.6 GPa. This transition was interpreted as an incongruent melting of the low temperature/high pressure B-GO intercalated structure with five layers of 1-octanol parallel to GO sheets (L-solvate), resulting in the formation of a four-layered structure that is stable under ambient conditions (A-solvate). Vacuum heating allows the removal of 1-octanol from the A-solvate layer by layer, while distinct sets of (00 l) reflections are observed for three-, two-, and one-layered solvate phases. Step by step removal of the 1-octanol layers results in changes of distance between graphene oxide planes by similar to 4.5 angstrom. This experiment proved that both L- and A-solvates are structures with layers of 1-octanol parallel to GO planes. Unusual intercalation with up to five distinct layers of 1-octanol is remarkably different from the behaviour of small alcohol molecules (methanol and ethanol), which intercalate B-GO structure with only one layer under ambient conditions and a maximum of two layers at lower temperatures or higher pressures. The data presented in this study make it possible to rule out a change in the orientation of alcohol molecules from parallel to perpendicular to the GO planes, as suggested in the 1960s to explain larger expansion of the GO lattice due to swelling with larger alcohols.

  • 11.
    Klechikov, Alexey
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Yu, Junchun
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Thomas, Diana
    Sharifi, Tiva
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Talyzin, Alexandr V.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Structure of graphene oxide membranes in solvents and solutions2015In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 7, no 37, p. 15374-15384Article in journal (Refereed)
    Abstract [en]

    The change of distance between individual graphene oxide sheets due to swelling is the key parameter to explain and predict permeation of multilayered graphene oxide (GO) membranes by various solvents and solutions. In situ synchrotron X-ray diffraction study shows that swelling properties of GO membranes are distinctly different compared to precursor graphite oxide powder samples. Intercalation of liquid dioxolane, acetonitrile, acetone, and chloroform into the GO membrane structure occurs with maximum one monolayer insertion (Type I), in contrast with insertion of 2-3 layers of these solvents into the graphite oxide structure. However, the structure of GO membranes expands in liquid DMSO and DMF solvents similarly to precursor graphite oxide (Type II). It can be expected that Type II solvents will permeate GO membranes significantly faster compared to Type I solvents. The membranes are found to be stable in aqueous solutions of acidic and neutral salts, but dissolve slowly in some basic solutions of certain concentrations, e.g. in NaOH, NaHCO3 and LiF. Some larger organic molecules, alkylamines and alkylammonium cations are found to intercalate and expand the lattice of GO membranes significantly, e.g. up to similar to 35 angstrom in octadecylamine/methanol solution. Intercalation of solutes into the GO structure is one of the limiting factors for nano-filtration of certain molecules but it also allows modification of the inter-layer distance of GO membranes and tuning of their permeation properties. For example, GO membranes functionalized with alkylammonium cations are hydrophobized and they swell in non-polar solvents.

  • 12.
    Luong, N. Tan
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Holmboe, Michael
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Boily, Jean-Francois
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    MgO nanocube hydroxylation by nanometric water films2023In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 15, no 24, p. 10286-10294Article in journal (Refereed)
    Abstract [en]

    Hydrophilic nanosized minerals exposed to air moisture host thin water films that are key drivers of reactions of interest in nature and technology. Water films can trigger irreversible mineralogical transformations, and control chemical fluxes across networks of aggregated nanomaterials. Using X-ray diffraction, vibrational spectroscopy, electron microscopy, and (micro)gravimetry, we tracked water film-driven transformations of periclase (MgO) nanocubes to brucite (Mg(OH)2) nanosheets. We show that three monolayer-thick water films first triggered the nucleation-limited growth of brucite, and that water film loadings continuously increased as newly-formed brucite nanosheets captured air moisture. Small (8 nm-wide) nanocubes were completely converted to brucite under this regime while growth on larger (32 nm-wide) nanocubes transitioned to a diffusion-limited regime when (∼0.9 nm-thick) brucite nanocoatings began hampering the flux of reactive species. We also show that intra- and inter-particle microporosity hosted a hydration network that sustained GPa-level crystallization pressures, compressing interlayer brucite spacing during growth. This was prevalent in aggregated 8 nm wide nanocubes, which formed a maze-like network of slit-shaped pores. By resolving the impact of nanocube size and microporosity on reaction yields and crystallization pressures, this work provides new insight into the study of mineralogical transformations induced by nanometric water films. Our findings can be applied to structurally related minerals important to nature and technology, as well as to advance ideas on crystal growth under nanoconfinement.

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  • 13. McDonagh, Birgitte H.
    et al.
    Volden, Sondre
    Lystvet, Sina M.
    Singh, Gurvinder
    Ese, Marit-Helen G.
    Ryan, Joseph A.
    Lindgren, Mikael
    Sandvig, Axel
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience. Norwegian Univ Sci & Technol NTNU, Fac Med, Dept Neurosci, N-7491 Trondheim, Norway.
    Sandvig, Ioanna
    Glomm, Wilhelm R.
    Self-assembly and characterization of transferrin-gold nanoconstructs and their interaction with bio-interfaces2015In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 7, no 17, p. 8062-8070Article in journal (Refereed)
    Abstract [en]

    Transferrin (Tf) conjugated to gold nanoparticles and clusters combine the protein's site-specific receptor targeting capabilities with the optical properties imparted by the nano-sized gold. We have described two different synthesis protocols, one yielding fluorescent Tf-stabilized gold nanoclusters (AuNCs) and one yielding Tf-stabilized gold nanoparticles that exhibit localized surface plasmon resonance. We demonstrate that the synthetic route employed has a large influence both on the gold nanostructure formed, and also on the structural integrity of the protein. A slight protein unfolding allows stronger interaction with lipids, and was found to significantly perturb lipid monolayers. Interactions between the protein-gold nanostructures and three different cell types were also assessed, indicating that the enhanced membrane affinity may be attributed to intercellular membrane differences.

  • 14.
    Messina, Gabriele C.
    et al.
    Plasmon Nanostructures, Istituto Italiano di Tecnologia, Genova, Italy.
    Zambrana-Puyalto, Xavier
    Plasmon Nanostructures, Istituto Italiano di Tecnologia, Genova, Italy.
    Maccaferri, Nicolò
    Department of Physics and Materials Science, University of Luxembourg, Luxembourg.
    Garoli, Denis
    Plasmon Nanostructures, Istituto Italiano di Tecnologia, Genova, Italy.
    De Angelis, Francesco
    Plasmon Nanostructures, Istituto Italiano di Tecnologia, Genova, Italy.
    Two-state switchable plasmonic tweezers for dynamic manipulation of nano-objects2020In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 12, no 15, p. 8574-8581Article in journal (Refereed)
    Abstract [en]

    In this work, we present a plasmonic platform capable of trapping nano-objects in two different spatial configurations. The switch between the two trapping states, localized on the tip and on the outer wall of a vertical gold nanochannel, can be activated by varying the focusing position of the excitation laser along the main axis of the nanotube. We show that the switching of the trapping site is induced by changes in the distribution of the electromagnetic field and of the trapping force. The “inner” and “outer” trapping states are characterized by a static and a dynamic behavior respectively, and their stiffness is measured by analyzing the positions of the trapped specimens as a function of time. In addition, we demonstrate that the stiffness of the static state is high enough to trap particles with diameter as small as 40 nm. These results show a simple, controllable way to generate a switchable two-state trapping regime, which could be used as a model for the study of dynamic trapping or as a mechanism for the development of nanofluidic devices.

  • 15.
    Ponzellini, Paolo
    et al.
    Istituto Italiano di Tecnologia, Genova, Italy.
    Zambrana-Puyalto, Xavier
    Istituto Italiano di Tecnologia, Genova, Italy.
    Maccaferri, Nicolò
    Istituto Italiano di Tecnologia, Genova, Italy.
    Lanzanò, Luca
    Istituto Italiano di Tecnologia, Genova, Italy.
    De Angelis, Francesco
    Istituto Italiano di Tecnologia, Genova, Italy.
    Garoli, Denis
    Istituto Italiano di Tecnologia, Genova, Italy.
    Plasmonic zero mode waveguide for highly confined and enhanced fluorescence emission2018In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 10, no 36, p. 17362-17369Article in journal (Refereed)
    Abstract [en]

    We fabricate a plasmonic nanoslot that is capable of performing enhanced single molecule detection at 10 μM concentrations. The nanoslot combines the tiny detection volume of a zero-mode waveguide and the field enhancement of a plasmonic nanohole. The nanoslot is fabricated on a bi-metallic film formed by the sequential deposition of gold and aluminum on a transparent substrate. Simulations of the structure yield an average near-field intensity enhancement of two orders of magnitude at its resonant frequency. Experimentally, we measure the fluorescence stemming from the nanoslot and compare it with that of a standard aluminum zero-mode waveguide. We also compare the detection volume for both structures. We observe that while both structures have a similar detection volume, the nanoslot yields a 25-fold fluorescence enhancement.

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  • 16. Sun, Jinhua
    et al.
    Iakunkov, Artem
    Rebrikova, Anastasia
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Talyzin, Alexandr V.
    Exactly matched pore size for the intercalation of electrolyte ions determined using the tunable swelling of graphite oxide in supercapacitor electrodes2018In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 10, no 45, p. 21386-21395Article in journal (Refereed)
    Abstract [en]

    The intercalation of solvent molecules and ions into sub-nanometer-sized pores is one of the most disputed subjects in the electrochemical energy storage applications of porous materials. Here, we demonstrate that the temperature- and concentration-dependent swelling of graphite oxide (GO) can be used to determine the smallest pore size required for the intercalation of electrolyte ions into hydrophilic pores. The structure of Brodie graphite oxide (BGO) in acetonitrile can be temperature-switched between the ambient one-layer solvate with an interlayer distance of approximate to 8.9 angstrom and the two-layer solvate (approximate to 12.5 angstrom) at low temperature, thus providing slit pores of approximately 2.5 and 6 angstrom. Using in situ synchrotron radiation X-ray diffraction (XRD) and the temperature dependence of capacitance in supercapacitor devices, we found that solvated tetraethylammonium tetrafluoroborate (TEA-BF4) ions do not penetrate into both the 2.5 and 6 angstrom slit pores formed by BGO interlayers. However, increasing the electrolyte concentration results in the formation of a new phase at low temperature. This phase shows a distinct interlayer distance of approximate to 15-16.6 angstrom, which corresponds to the insertion of partly desolvated TEA-BF4 ions. Therefore, the remarkable ability of the GO structure to adopt variable interlayer distances allows for the determination of pore sizes that are optimal for solvated TEA-BF4 ions (about 9-10 angstrom). The intercalation of TEA-BF4 ions into the BGO structure is also detected as an anomaly in the temperature dependence of supercapacitor performance. The BGO structure remains to be expanded, even after the removal of acetonitrile, adopting an interlayer distance of approximate to 10 angstrom.

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  • 17.
    Talyzin, Alexandr
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Hausmaninger, Thomas
    Umeå University, Faculty of Science and Technology, Department of Physics.
    You, Shujie
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Szabo, Tamas
    Department of Physical Chemistry and Materials Science, University of Szeged, Szeged, Hungary.
    The structure of graphene oxide membranes in liquid water, ethanol and water – ethanol mixtures2014In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 6, p. 272-281Article in journal (Refereed)
    Abstract [en]

    The structure of graphene oxide (GO) membranes was studied in situ in liquid solvents using synchrotron radiation X-ray diffraction in a broad temperature interval. GO membranes are hydrated by water similarly to precursor graphite oxide powders but intercalation of alcohols is strongly hindered, which explains why the GO membranes are permeated by water and not by ethanol. Insertion of ethanol into the membrane structure is limited to only one monolayer in the whole studied temperature range, in contrast to precursor graphite oxide powders, which are intercalated with up to two ethanol monolayers (Brodie) and four ethanol monolayers (Hummers). As a result, GO membranes demonstrate the absence of “negative thermal expansion” and phase transitions connected to insertion/de-insertion of alcohols upon temperature variations reported earlier for graphite oxide powders. Therefore, GO membranes are a distinct type of material with unique solvation properties compared to parent graphite oxides even if they are composed of the same graphene oxide flakes.

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  • 18.
    Talyzin, Alexandr
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Klechikov, Alexey
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Korobov, Mikhail
    Rebrikova, Anastasiya T
    Avramenko, Nataliya V
    Gholami, M Fardin
    Severin, Nikolai
    Rabe, Jürgen P
    Delamination of graphite oxide in a liquid upon cooling2015In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 7, no 29, p. 12625-12630Article in journal (Refereed)
    Abstract [en]

    Graphite oxide (GO) in liquid acetonitrile undergoes a transition from an ordered phase around ambient temperature to a gel-like disordered phase at temperatures below 260 K, as demonstrated by in situ X-ray diffraction. The stacking order of GO layers is restored below the freezing point of acetonitrile (199 K). The reversible swelling transition between a stacked crystalline phase and an amorphous delaminated state observed upon cooling provides an unusual example of increased structural disorder at lower temperatures. The formation of the gel-like phase is attributed to the thermo-responsive conformational change of individual GO flakes induced by stronger solvation. Scanning force microscopy demonstrates that GO flakes deposited onto a solid substrate from acetonitrile dispersions at a temperature below 260 K exhibit corrugations and wrinkling which are not observed for the flakes deposited at ambient temperature. The thermo-responsive transition between the delaminated and stacked phases reported here can be used for sonication-free dispersion of graphene oxide, micro-container applications, or the preparation of new composite materials.

  • 19. Verre, R.
    et al.
    Maccaferri, Nicolò
    Department of Physics, Chalmers University of Technology, Göteborg, Sweden; CIC nanoGUNE, E-20018 Donostia-San Sebastian, Spain.
    Fleischer, K.
    Svedendahl, M.
    Odebo Länk, N.
    Dmitriev, A.
    Vavassori, P.
    Shvets, I. V.
    Käll, M.
    Polarization conversion-based molecular sensing using anisotropic plasmonic metasurfaces2016In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 8, no 20, p. 10576-10581Article in journal (Refereed)
    Abstract [en]

    Anisotropic media induce changes in the polarization state of transmitted and reflected light. Here we combine this effect with the refractive index sensitivity typical of plasmonic nanoparticles to experimentally demonstrate self-referenced single wavelength refractometric sensing based on polarization conversion. We fabricated anisotropic plasmonic metasurfaces composed of gold dimers and, as a proof of principle, measured the changes in the rotation of light polarization induced by biomolecular adsorption with a surface sensitivity of 0.2 ng cm−2. We demonstrate the possibility of miniaturized sensing and we show that experimental results can be reproduced by analytical theory. Various ways to increase the sensitivity and applicability of the sensing scheme are discussed.

  • 20. Vorobiev, Alexei
    et al.
    Dennison, Andrew
    Chernyshov, Dmitry
    Skyrpnychuck, Vasyl
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Barbero, David
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Talyzin, Alexandr
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Graphene oxide hydration and solvation: an in situ neutron reflectivity study2014In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 6, no 20, p. 12151-12156Article in journal (Refereed)
    Abstract [en]

    Graphene oxide membranes were recently suggested for applications in separation of ethanol from water using a vapor permeation method. Using isotope contrast, neutron reflectivity was applied to evaluate the amounts of solvents intercalated into a membrane from pure and binary vapors and to evaluate the selectivity of the membrane permeation. Particularly, the effect of D2O, ethanol and D2O–ethanol vapours on graphene oxide (GO) thin films (25 nm) was studied. The interlayer spacing of GO and the amount of intercalated solvents were evaluated simultaneously as a function of vapour exposure duration. The significant difference in neutron scattering length density between D2O and ethanol allows distinguishing insertion of each component of the binary mixture into the GO structure. The amount of intercalated solvent at saturation corresponds to 1.4 molecules per formula unit for pure D2O (1.4 monolayers) and 0.45 molecules per formula unit (one monolayer) for pure ethanol. This amount is in addition to H2O absorbed at ambient humidity. Exposure of the GO film to ethanol–D2O vapours results in intercalation of GO with both solvents even for high ethanol concentration. A mixed D2O–ethanol layer inserted into the GO structure is water enriched compared to the composition of vapours due to slower ethanol diffusion into GO interlayers

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