References of "Ponzellini, Paolo"
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See detailFörster-resonance energy transfer between diffusing molecules and a functionalized plasmonic nanopore
Zambrana-Puyalto, Xavier; Ponzellini, Paolo; Maccaferri, Nicolò UL et al

in Physical Review Applied (2020), 14(5), 054065

Plasmonic nanopores are the subject of extensive investigations as a potential platform to enable efficient optical read-out in translocation experiments with biomolecules such as DNA and proteins. They ... [more ▼]

Plasmonic nanopores are the subject of extensive investigations as a potential platform to enable efficient optical read-out in translocation experiments with biomolecules such as DNA and proteins. They allow for the engineering of electromagnetic fields at the nanoscale, which are typically used to enhance the emission efficiency of fluorescent molecules. Their features make them suitable for detection strategies based on the energy transfer between translocating molecules and the nanopore itself. Here, we have carried out an optical experiment to show that a handful of diffusing dyes acting as donors can exchange energy via Fster resonance energy transfer (FRET) with a gold nanopore functionalized with dyes behaving as acceptors. The FRET pair is composed of ATTORho6G (donor) and Alexa610 (acceptor). To perform this proof-of-concept experiment, we used a gold nanopore with a diameter of 80 nm, prepared on a Si3N4 membrane. We have observed that the presence of the acceptors on the walls of the nanopore reduces the lifetime of the diffusing donors. In addition, we have observed that the presence of the acceptors reduces the fluorescence signal on the donor detection channel and increases the fluorescence signal on the acceptor detection channel. The combination of these three effects gives us enough evidence to claim that the diffusing donors exchange energy with the functionalized nanopore via FRET, despite the relatively large size of the nanopore. The FRET efficiency of the process has been found to be of the order of 30%, which is in a fairly good agreement with a theoretical value obtained using a simplified model. [less ▲]

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See detailSite-Selective Integration of MoS2 Flakes on Nanopores by Means of Electrophoretic Deposition
Mosconi, Dario; Giovannini, Giorgia; Jacassi, Andrea et al

in ACS Omega (2019), 4(5), 9294-9300

Here, we propose an easy method for site-selective deposition of two-dimensional (2D) material flakes onto nanoholes by means of electrophoretic deposition. This method can be applied to both simple flat ... [more ▼]

Here, we propose an easy method for site-selective deposition of two-dimensional (2D) material flakes onto nanoholes by means of electrophoretic deposition. This method can be applied to both simple flat nanostructures and complex three-dimensional structures incorporating nano- holes. The deposition method is here used for the decoration of large ordered arrays of plasmonic structures with either a single or few layers of MoS2 . In principle, the plasmonic field generated by the nanohole can significantly interact with the 2D layer leading to enhanced light−material interaction. This makes our platform an ideal system for hybrid 2D material/ plasmonic investigations. The engineered deposition of 2D materials on plasmonic nanostructures is useful for several important applications such as enhanced light emission, strong coupling, hot-electron generation, and 2D material sensors. Site-selective integration of MoS2 flakes on nanopores by means of electrophoretic deposition. [less ▲]

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See detailA hybrid metal–dielectric zero mode waveguide for enhanced single molecule detection
Zambrana-Puyalto, Xavier; Ponzellini, Paolo; Maccaferri, Nicolò UL et al

in Chemical Communications (2019)

We fabricated hybrid metal–dielectric nanoslots and measured their optical response at three different wavelengths. The nanostructure is fabricated on a bilayer film formed by the sequential deposition of ... [more ▼]

We fabricated hybrid metal–dielectric nanoslots and measured their optical response at three different wavelengths. The nanostructure is fabricated on a bilayer film formed by the sequential deposition of silicon and gold on a transparent substrate. The optical characterization is done via fluorescence spectroscopy measurements. We characterized the fluorescence enhancement, as well as the lifetime and the detection volume reduction for each wavelength. We observe that the hybrid metal–dielectric nanoslots behave as enhanced zero mode waveguides in the near-infrared spectral region. Their detection volume is such that they can perform enhanced single-molecule detection at tens of μM. We compared their behavior with that of a golden ZMW, and we demonstrated that the dielectric silicon layer improves both the optical performance and the stability of the device. [less ▲]

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See detailFRET Characterization of Hollow Plasmonic Nanoantennas
Maccaferri, Nicolò UL; Ponzellini, Paolo; Giovannini, Giorgia et al

in Proceedings of SPIE : The International Society for Optical Engineering (2019), 10894

We fabricated hollow nanoantennas with varying inner channels sizes on a gold-covered silicon nitride membrane. Our fabrication technique allowed us to narrow the size of the inner channels down to 15nm ... [more ▼]

We fabricated hollow nanoantennas with varying inner channels sizes on a gold-covered silicon nitride membrane. Our fabrication technique allowed us to narrow the size of the inner channels down to 15nm. We managed to exclusively decorate the tips of the antennas with thiol-conjugated dyes by creating a concentration gradient through the nanoantennas. Finally, we characterized the antennas in terms of their effect on the lifetime of dyes. We used Atto 520 and Atto 590 for the experiments. We carried out experiments with the antennas decorated with Atto 520, with Atto 590 as well as with the two Atto dyes at the same time. The experiments carried out with the antennas decorated with Atto 520 only and Atto 590 only yielded a lifetime reduction with respect to the confocal case. Interestingly, their lifetime reductions were significantly different. Then, we decorated the antennas with the two dyes at the same time. Even though we could not control the distance between the two dyes, FRET effects were clearly observed. The FRET effects were found to be dependent on the size of the inner channel. We believe that our tip decorated hollow nanoantennas could find application in FRET-based single molecule nanopore technologies. [less ▲]

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See detailSite-selective functionalization of plasmonic nanopores for enhanced fluorescence emission rate and Förster Resonance Energy Transfer
Zambrana-Puyalto, Xavier; Maccaferri, Nicolò UL; Ponzellini, Paolo et al

in Nanoscale Advances (2019), 1(6), 2454-2461

In this work, we use a site-selective functionalization strategy to decorate plasmonic nanopores with fluorescent dyes. Using an easy and robust fabrication method, we manage to build plasmonic rings on ... [more ▼]

In this work, we use a site-selective functionalization strategy to decorate plasmonic nanopores with fluorescent dyes. Using an easy and robust fabrication method, we manage to build plasmonic rings on top of dielectric nanotubes with different inner diameters. The modulation of the dimension of the nanopores allows us to tailor their field confinement and their Purcell Factor in the visible spectral range. In order to investigate how the changes in geometry influence the fluorescence emission rate efficiency, thiol-conjugated dyes are anchored on the plasmonic ring, thus forming a functional nanopore. We study the lifetime of ATTO 520 and ATTO 590 attached in two different configurations: single dye, and FRET pair. For the single dye configuration, we observe that the lifetime of both single dyes decreases as the size of the nanopore is reduced. The smallest nanopores yield an experimental Purcell Factor of 6. For the FRET pair configuration, we measure two regimes. For large nanopore sizes, the FRET efficiency remains constant. Whereas for smaller sizes, the FRET efficiency increases from 30 up to 45% with a decrease of the nanopore size. These findings, which have been supported by numerical simulations, may open new perspectives towards energy transfer engineering in plasmonic nanopores with potential applications in photonics and biosensing, in particular in single-molecule detection and sequencing.In this work, we use a site-selective functionalization strategy to decorate plasmonic nanopores with fluorescent dyes. Using an easy and robust fabrication method, we manage to build plasmonic rings on top of dielectric nanotubes with different inner diameters. The modulation of the dimension of the nanopores allows us to tailor their field confinement and their Purcell Factor in the visible spectral range. In order to investigate how the changes in geometry influence the fluorescence emission rate efficiency, thiol-conjugated dyes are anchored on the plasmonic ring, thus forming a functional nanopore. We study the lifetime of ATTO 520 and ATTO 590 attached in two different configurations: single dye, and FRET pair. For the single dye configuration, we observe that the lifetime of both single dyes decreases as the size of the nanopore is reduced. The smallest nanopores yield an experimental Purcell Factor of 6. For the FRET pair configuration, we measure two regimes. For large nanopore sizes, the FRET efficiency remains constant. Whereas for smaller sizes, the FRET efficiency increases from 30 up to 45% with a decrease of the nanopore size. These findings, which have been supported by numerical simulations, may open new perspectives towards energy transfer engineering in plasmonic nanopores with potential applications in photonics and biosensing, in particular in single-molecule detection and sequencing. [less ▲]

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See detailPlasmonic zero mode waveguide for highly confined and enhanced fluorescence emission
Ponzellini, Paolo; Zambrana-Puyalto, Xavier; Maccaferri, Nicolò UL et al

in Nanoscale (2018), 10(36), 17362-17369

We fabricate a plasmonic nanoslot that is capable of performing enhanced single molecule detection at 10 muM concentrations. The nanoslot combines the tiny detection volume of a zero-mode waveguide and ... [more ▼]

We fabricate a plasmonic nanoslot that is capable of performing enhanced single molecule detection at 10 muM 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. [less ▲]

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See detailNanoporous gold decorated with silver nanoparticles as large area efficient SERS substrate
Ardini, Matteo; Huang, Jian-An; Sanchez-Sanchez, Carlos et al

in Proceedings of SPIE : The International Society for Optical Engineering (2017), 10346

Nanoporous gold is a very promising material platform for several plasmonic applications. Nanoporous gold can be formed by dealloying Au–Ag alloys, previously grown by means of Ag-Au co-sputtering. The ... [more ▼]

Nanoporous gold is a very promising material platform for several plasmonic applications. Nanoporous gold can be formed by dealloying Au–Ag alloys, previously grown by means of Ag-Au co-sputtering. The optical response is completely determined by the nanostructured film features, that only depend on the initial alloy composition. It has been extensively used as SERS substrate both as thin film and nanofabricated fancy designs. Here we explore the potential application of nanoporous gold as SERS substrate as it is coupled and decorated with Ag nanoparticles. Significant enhancement has been observed in comparison with bare nanoporous film. [less ▲]

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