Common-path interferometric label-free protein sensing with resonant dielectric nanostructures

Barth, Isabel; Conteduca, Donato; Reardon, Christopher; Johnson, Steven D.; Krauss, Thomas F.

doi:10.1038/s41377-020-0336-6

Cited by 60 publications

(40 citation statements)

References 24 publications

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“…We have recently also demonstrated an interferometric approach based on guided-mode resonances 40 where we have shown the detection of 1 pg/ml of procalcitonin (PCT) with very high SNR. We note that the main advantage of the nanohole array configuration shown here is its ability to obtain a similar sensing performance together with the imaging capability.…”

Section: Resultsmentioning

confidence: 99%

Dielectric nanohole array metasurface for high-resolution near-field sensing and imaging

et al. 2021

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Dielectric metasurfaces support resonances that are widely explored both for far-field wavefront shaping and for near-field sensing and imaging. Their design explores the interplay between localised and extended resonances, with a typical trade-off between Q-factor and light localisation; high Q-factors are desirable for refractive index sensing while localisation is desirable for imaging resolution. Here, we show that a dielectric metasurface consisting of a nanohole array in amorphous silicon provides a favourable trade-off between these requirements. We have designed and realised the metasurface to support two optical modes both with sharp Fano resonances that exhibit relatively high Q-factors and strong spatial confinement, thereby concurrently optimizing the device for both imaging and biochemical sensing. For the sensing application, we demonstrate a limit of detection (LOD) as low as 1 pg/ml for Immunoglobulin G (IgG); for resonant imaging, we demonstrate a spatial resolution below 1 µm and clearly resolve individual E. coli bacteria. The combined low LOD and high spatial resolution opens new opportunities for extending cellular studies into the realm of microbiology, e.g. for studying antimicrobial susceptibility.

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Section: Resultsmentioning

confidence: 99%

Dielectric nanohole array metasurface for high-resolution near-field sensing and imaging

et al. 2021

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“…Very recently, a resonant Si 3 N 4 grating on silica was measured to show a phase sensitivity of 289 π per RIU. [ 38 ] Our pillar array can be designed to have an anisotropic unit cell [ 20 ] with polarization‐dependent phase changes at normal incidence, and thus common‐path interferometric phase interrogation schemes [ 38 ] can be implemented.…”

Section: Figurementioning

confidence: 99%

“…The sensitivity can be over 1600 π per RIU in the most sensitive range of the phase curve, which can be employed to significantly improve the detection limit based on phase-sensitive measurements. [36][37][38] Note that if the minimal reflection does not reach zero, the 2π phase flip still exists around the reflection dip, though the phase transition will become less steep ( Figure S7, Supporting Information). Very recently, a resonant Si 3 N 4 grating on silica was measured to show a phase sensitivity of 289 π per RIU.…”

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confidence: 99%

Low‐Index‐Contrast Dielectric Lattices on Metal for Refractometric Sensing

Dong

Chen

Huang

et al. 2020

Advanced Optical Materials

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In this context, metal nanostructures with localized surface plasmon resonances (LSPRs) have attracted extensive attention. [2] LSPRs can be excited with wide-field normal-incidence illumination, and the optical setup for sensing can be simply constructed based on standard optical microscopes. [3] Periodic plasmonic nanostructures can offer additional advantages, [4] for example, a much narrower resonance linewidth (compared to LSPRs) that is beneficial for measuring a small spectral shift. However, the intense optical fields on the surface of plasmonic nanostructures can result in dissipative loss and lead to heating. Recently, periodic arrays of high-index dielectric nanostructures with collective resonances have been proposed as an alternative. [5-9] However, for periodic arrays of high-index dielectric nanostructures, even with broken inplane symmetry (so-called quasi-BIC; bound states in the continuum), [7,8] the bulk sensitivity (defined as the spectral shift upon the change in the bulk refractive index of the surrounding environment) is much lower than that of plasmonic arrays with the same lattice spacing. The collective lattice resonance stemming from the diffractive coupling in a periodic array of either metal [10-12] or high-index dielectric nanoparticles [13] requires a symmetric refractive-index environment between the bottom substrate and the upper cladding (e.g., aqueous buffers in sensing). [14-17] An asymmetric environment can inhibit long-range coupling between nanoparticles and suppress lattice resonances. In optical sensing, a periodic array of either metal or high-index dielectric nanoparticles is usually fabricated on a transparent substrate and exposed to solutions with different refractive indices. The index-mismatch between widely used quartz substrates (n ≈ 1.5) and aqueous buffers (n ≈ 1.33) can broaden the resonances and deteriorate the bulk sensitivity. [18] Although for sensing in aqueous buffers, one can find fluoropolymer (Cytop) with refractive index close to water to create a symmetric environment, [18,19] it is highly desirable to have a platform that can maintain high-quality resonances when subjected to a relatively large change in the bulk refractive index. (A symmetric refractive-index environment may not be required in a periodic structure with high-quality resonances of quasi-BIC type, for which the bulk sensitivity, however, is not high in the published literature. [7,8]) We recently reported that a hybrid system composed of low-index dielectric pillar arrays on a metal film can support This article reports refractometric sensing using two optical resonances of different types supported by TiO 2 nanopillar arrays on a gold film, which can be exposed to aqueous or organic environments. One lattice resonance, with enhanced electric fields extending into the surrounding environment, can maintain a quality factor Q > 200 when the bulk refractive index of the surrounding environment varies in a large range from 1.33 to 1.58. This lattice resonance exhibits not only sharp trans...

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“…A similar performance was achieved by Dey et al with an NHA configuration combined with an interferometric approach [31] where the interference between two spatially separated, orthogonally polarized beams was measured. Measuring the relative difference between two collinear beams, rather than the absolute change of an individual one, minimizes the impact of mechanical, thermal, and optical source noise, which we have recently shown to be advantageous also for protein measurements [43].…”

Section: Plasmonic Nanohole Arraysmentioning

confidence: 99%

Nanophotonics for bacterial detection and antimicrobial susceptibility testing

2020

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Photonic biosensors are a major topic of research that continues to make exciting advances. Technology has now improved sufficiently for photonics to enter the realm of microbiology and to allow for the detection of individual bacteria. Here, we discuss the different nanophotonic modalities used in this context and highlight the opportunities they offer for studying bacteria. We critically review examples from the recent literature, starting with an overview of photonic devices for the detection of bacteria, followed by a specific analysis of photonic antimicrobial susceptibility tests. We show that the intrinsic advantage of matching the optical probed volume to that of a single, or a few, bacterial cell, affords improved sensitivity while providing additional insight into single-cell properties. We illustrate our argument by comparing traditional culture-based methods, which we term macroscopic, to microscopic free-space optics and nanoscopic guided-wave optics techniques. Particular attention is devoted to this last class by discussing structures such as photonic crystal cavities, plasmonic nanostructures and interferometric configurations. These structures and associated measurement modalities are assessed in terms of limit of detection, response time and ease of implementation. Existing challenges and issues yet to be addressed will be examined and critically discussed.

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Common-path interferometric label-free protein sensing with resonant dielectric nanostructures

Cited by 60 publications

References 24 publications

Dielectric nanohole array metasurface for high-resolution near-field sensing and imaging

Dielectric nanohole array metasurface for high-resolution near-field sensing and imaging

Low‐Index‐Contrast Dielectric Lattices on Metal for Refractometric Sensing

Nanophotonics for bacterial detection and antimicrobial susceptibility testing

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