Zero-mode waveguides can be made better: fluorescence enhancement with rectangular aluminum nanoapertures from the visible to the deep ultraviolet

Abstract

Nanoapertures milled in metallic films called zero-mode waveguides (ZMWs) overcome the limitations of classical confocal microscopes by enabling single molecule analysis at micromolar concentrations with improved fluorescence brightness. While the...

Purcell radiative rate enhancement of label-free proteins with ultraviolet aluminum plasmonics

“…Nanoapertures with 65 nm diameter (figure 1(d)) were milled using gallium-based focused ion beam (FEI dual beam DB235 Strata, voltage 30 kV, ion current 10 pA). This nanoaperture diameter corresponds to a cut-off diameter in the UV [15], where the real part of the propagation constant vanishes and the intensity evanescently decays inside the nanoaperture. While smaller diameters would further promote the localization of electric field and the excitation intensity enhancement, significant quenching losses occur for diameter below the cut-off, which decrease the overall fluorescence enhancement [14].…”

Preventing Corrosion of Aluminum Metal with Nanometer-Thick Films of Al2O3 Capped with TiO2 for Ultraviolet Plasmonics

“…B / F PMT is the ratio of background counts B to the total detected fluorescence signal F PMT , N mol is the number of detected molecules, τ d is the diffusion, and κ is the aspect ratio of the detection volume, which is kept at a constant value of 1 according to our earlier works. ,, At an excitation power of 5 μW, the background B amounts to 1.2 kcounts/s, while it increases to 2.7 kcounts/s at 20 μW. The background stems mostly from the GODCAT fluorescence, and it saturates at high power.…”

“…Here, we assess the UV photocorrosion protection performance of nanometer-thick layers of various metal oxides deposited by ALD or PECVD on top of aluminum nanoapertures. Individual circular nanoapertures of 65 nm diameter milled in a 100 nm-thick aluminum film form a simple and reproducible platform to check the nanostructure photostability in the presence of water and UV irradiation. , Beyond the choice of the best material for the nanometer capping layer, we also discuss the influence of other experimental conditions like the laser wavelength, its operation mode, or the pH of the solution. In the presence of water, aluminum UV plasmonics will face the problem of photocorrosion.…”

Gold Ion Beam Milled Gold Zero-Mode Waveguides

“…Having a diameter smaller than the wavelength of excitation light, the ZMW acts as a plasmonic resonator that may enhance fluorescence absorption and emission [ 18 , 19 , 20 , 21 ]. As a new approach in SMS, the characterization of ZMW related to size and shape [ 21 , 22 , 23 , 24 , 25 ], metal and layering compositions [ 18 , 21 , 22 , 26 , 27 , 28 , 29 ], excitation wavelength [ 19 ], spatial position of fluorophores relative to the metal structures [ 30 , 31 , 32 ], and spectral overlap of the surface plasmon resonance and excitation/emission of fluorophores [ 33 , 34 , 35 , 36 , 37 ] have been highly active areas of research. The geometry and opacity of the ZMW enables measurements at physiological concentrations (∼1–100 μM) in SMS [ 30 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 ].…”