| 1. |
- Ardini, Matteo, et al.
(author)
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Live Intracellular Biorthogonal Imaging by Surface Enhanced Raman Spectroscopy using Alkyne-Silver Nanoparticles Clusters
- 2018
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In: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 8:1
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Journal article (peer-reviewed)abstract
- Live intracellular imaging is a valuable tool in modern diagnostics and pharmacology. Surface Enhanced Raman Spectroscopy (SERS) stands out as a non-destructive and multiplexed technique, but intracellular SERS imaging still suffers from interfering background from endogenous components. Here we show the assembly of small colloidal SERS probes with Raman signal in the cell-silent window of 1800–2900 cm−1 for biorthogonal intracellular SERS imaging of dopamine that was undistinguishable from the endogenous cell background. By linking colloidal silver nanoparticles with alkyne-dopamine adducts, clusters are formed by 2–6 nanoparticles spaced by tight interparticle gaps that exhibited high electric field enhancement and strong SERS signals of alkyne and dopamines. Due to the cell-silent signals of the alkyne, intracellular in-vitro Raman imaging shows that the dopamines on the internalized clusters remain distinguishable across the cytoplasm with good spatial resolution. Our method can be a general-purpose method for real-time imaging of biomolecules, such as proteins, peptides, DNA and drugs.
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| 2. |
- Caligiuri, Vincenzo, et al.
(author)
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Dry synthesis of bi-layer nanoporous metal films as plasmonic metamaterial
- 2024
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In: Nanophotonics. - : Walter de Gruyter. - 2192-8606 .- 2192-8614. ; 13:7, s. 1159-1167
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Journal article (peer-reviewed)abstract
- Nanoporous metals are a class of nanostructured materials finding extensive applications in multiple fields thanks to their unique properties attributed to their high surface area and interconnected nanoscale ligaments. They can be prepared following different strategies, but the deposition of an arbitrary pure porous metal is still challenging. Recently, a dry synthesis of nanoporous films based on the plasma treatment of metal thin layers deposited by physical vapour deposition has been demonstrated, as a general route to form pure nanoporous films from a large set of metals. An interesting aspect related to this approach is the possibility to apply the same methodology to deposit the porous films as a multilayer. In this way, it is possible to explore the properties of different porous metals in close contact. As demonstrated in this paper, interesting plasmonic properties emerge in a nanoporous Au–Ag bi-layer. The versatility of the method coupled with the possibility to include many different metals, provides an opportunity to tailor their optical resonances and to exploit the chemical and mechanical properties of components, which is of great interest to applications ranging from sensing, to photochemistry and photocatalysis.
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| 3. |
- Garoli, Denis, et al.
(author)
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Hybrid plasmonic nanostructures based on controlled integration of MoS2 flakes on metallic nanoholes
- 2018
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In: Nanoscale. - : Royal Society of Chemistry. - 2040-3364 .- 2040-3372. ; 10:36, s. 17105-17111
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Journal article (peer-reviewed)abstract
- 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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| 4. |
- Garoli, Denis, et al.
(author)
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Plasmonic Nanopores for Single-Molecule Detection and Manipulation : Toward Sequencing Applications
- 2019
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In: Nano Letters. - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 19:11, s. 7553-7562
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Research review (peer-reviewed)abstract
- Solid-state nanopore-based sensors are promising platforms for next-generation sequencing technologies, featuring label-free single-molecule sensitivity, rapid detection, and low-cost manufacturing. In recent years, solid-state nanopores have been explored due to their miscellaneous fabrication methods and their use in a wide range of sensing applications. Here, we highlight a novel family of solid-state nanopores which have recently appeared, namely plasmonic nanopores. The use of plasmonic nanopores to engineer electromagnetic fields around a nanopore sensor allows for enhanced optical spectroscopies, local control over temperature, thermophoresis of molecules and ions to/from the sensor, and trapping of entities. This Mini Review offers a comprehensive understanding of the current state-of-the-art plasmonic nano pores for single-molecule detection and biomolecular sequencing applications and discusses the latest advances and future perspectives on plasmonic nano-porebased technologies.
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| 5. |
- Giovannini, Giorgia, et al.
(author)
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Bio‐Assisted Tailored Synthesis of Plasmonic Silver Nanorings and Site‐Selective Deposition on Graphene Arrays
- 2020
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In: Advanced Optical Materials. - : John Wiley & Sons. - 2162-7568 .- 2195-1071. ; 8:4, s. 1901583-1901583
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Journal article (peer-reviewed)abstract
- The spontaneous interaction between noble metals and biological scaffolds enables simple and cost-effective synthesis of nanomaterials with unique features. Here, plasmonic silver nanorings are synthesized on a ring-like protein, i.e., a peroxiredoxin (PRX), and used to assemble large arrays of functional nanostructures. The PRX drives the seeding growth of metal silver under wet reducing conditions, yielding nanorings with outer and inner diameters down to 28 and 3 nm, respectively. The obtained hybrid nanostructures are selectively deposited onto a solid-state 2D membrane made of graphene in order to prepare plasmonic nanopores. In particular, the interaction between the graphene and the PRX allows for the simple preparation of ordered arrays of plasmonic nanorings on a 2D-material membrane. This fabrication process can be finalized by drilling a nanometer scale pore in the middle of the ring. Fluorescence spectroscopic measurements in combination with numerical simulations demonstrate the plasmonic effects induced in the metallic nanoring cavity. The prepared nanopores represent one of the first examples of hybrid plasmonic nanopore structures integrated on a 2D-material membrane. The diameter of the nanopore and the atomically thick substrate make this proof-of-concept approach particularly interesting for nanopore-based technologies and applications such as next-generation sequencing and single-molecule detection.
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| 6. |
- Henriksson, Nils, et al.
(author)
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Probing temperature changes using nonradiative processes in hyperbolic meta-antennas
- 2024
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In: ACS Applied Optical Materials. - : American Chemical Society (ACS). - 2771-9855.
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Research review (peer-reviewed)abstract
- Multilayered metal-dielectric nanostructures display both a strong plasmonic behavior and hyperbolic optical dispersion. The latter is responsible for the appearance of two separated radiative and nonradiative channels in the extinction spectrum of these structures. This unique property can open plenty of opportunities toward the development of multifunctional systems that simultaneously can behave as optimal scatterers and absorbers at different wavelengths, an important feature to achieve multiscale control of light-matter interactions in different spectral regions for different types of applications, such as optical computing or detection of thermal radiation. Nevertheless, the temperature dependence of the optical properties of these multilayered systems has never been investigated. In this work, we study how radiative and nonradiative processes in hyperbolic meta-antennas can probe temperature changes of the surrounding medium. We show that, while radiative processes are essentially not affected by a change in the external temperature, the nonradiative ones are strongly affected by a temperature variation. By combining experiments and temperature-dependent effective medium theory, we find that this behavior is connected to enhanced damping effects due to electron-phonon scattering. Contrary to standard plasmonic systems, a red-shift of the nonradiative mode occurs for small variations of the environment temperature. Our study shows that, to probe temperature changes, it is essential to exploit nonradiative processes in systems supporting plasmonic excitations, which can be used as very sensitive thermometers via linear absorption spectroscopy.
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| 7. |
- Hubarevich, Aliaksandr, et al.
(author)
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λ-DNA through Porous Materials—Surface-Enhanced Raman Scattering in a Simple Plasmonic Nanopore
- 2020
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In: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 124:41, s. 22663-22670
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Journal article (peer-reviewed)abstract
- Engineered electromagnetic fields in plasmonic nanopores enable enhanced optical detection for single-molecule sensing and sequencing. Here, a plasmonic nanopore prepared in a thick nanoporous film is used to investigate, by means of surface-enhanced Raman spectroscopy, the interaction between the metallic surface of the pore and a long-chain double-strand DNA molecule free to diffuse through the pore. We discuss how the matrix of the porous material can interact with the molecule thanks to: (i) transient aspecific interactions between the porous surface and DNA; (ii) diffusion; and (iii) thermal and optical forces exerted by the localized field in a metallic nanostructure on the DNA molecule. An interaction time up to tens of milliseconds enables us to collect high signal-to-noise Raman signatures, allowing an easy label-free reading of information from the DNA molecule. Moreover, to increase the rate of detection, we tested a polymeric porous hydrogel placed beneath the solid-state membrane. The hydrogel enables a slowdown of the molecule diffusion time, thus increasing the number of detected interaction events by a factor 20. The analysis of the observed Raman peaks and their relative intensities, combined with theoretical simulations, allows us to get further information on the process of translocation and the folding state and orientation of the translocating molecule. Our results demonstrate temporary adsorption of the DNA molecule on the porous material during the translocation due to the diffusion force. Finally, we provide a qualitative evaluation of the nucleotides' contents in the different groups of collected signal. The proposed approach can find interesting applications not only in DNA sensing and sequencing but also on generic nanopore spectroscopy.
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| 8. |
- Kuttruff, Joel, et al.
(author)
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Ultrafast all-optical switching enabled by epsilon-near-zero-tailored absorption in metal-insulator nanocavities
- 2020
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In: Communications Physics. - : Nature Publishing Group. - 2399-3650. ; 3:1
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Journal article (peer-reviewed)abstract
- Ultrafast control of light−matter interactions is fundamental in view of new technological frontiers of information processing. However, conventional optical elements are either static or feature switching speeds that are extremely low with respect to the time scales at which it is possible to control light. Here, we exploit the artificial epsilon-near-zero (ENZ) modes of a metal-insulator-metal nanocavity to tailor the linear photon absorption of our system and realize a nondegenerate all-optical ultrafast modulation of the reflectance at a specific wavelength. Optical pumping of the system at its high energy ENZ mode leads to a strong redshift of the low energy mode because of the transient increase of the local dielectric function, which leads to a sub-3-ps control of the reflectance at a specific wavelength with a relative modulation depth approaching 120%.
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| 9. |
- Lanzavecchia, German, et al.
(author)
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Plasmon-driven photochemistry for metallic nanopore arrays fabrication
- 2023
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In: 2023 Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference, CLEO/Europe-EQEC 2023. - : IEEE. - 9798350345995 - 9798350346008
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Conference paper (peer-reviewed)abstract
- We show a process for the fabrication of nanopores arrays via photocatalysis triggered by electromagnetic field enhancement in plasmonic structures immersed in metallic salt solutions and generating hotspots causing pore diameter reduction below 5 nm.
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| 10. |
- Lanzavecchia, German, et al.
(author)
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Plasmonic photochemical process for preparation of metallic nanopore arrays
- 2023
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In: CLEO 2023. - : Optical Society of America. - 9781957171258
-
Conference paper (peer-reviewed)abstract
- We report a process for fabricating sub-10 nm nanopores via photocatalysis caused by electromagnetic field enhancement in plasmonic structures, which immersed in metallic salt solutions triggers hotspots for metallic deposition causing pore diameter shrinkage.
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