Background-Free Bottom-Up Plasmonic Arrays with Increased Sensitivity, Specificity and Shelf Life for SERS Detection Schemes

Yüksel, Sezin; Ziegler, Mario; Goerke, Sebastian; Hübner, Uwe; Pollok, Kilian; Langenhorst, F.; Weber, Karina; Cialla‐May, Dana; Popp, Jürgen

doi:10.1021/acs.jpcc.5b01389

Cited by 23 publications

(17 citation statements)

References 49 publications

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“…It is known that the SERS activity can deteriorate due to surface oxidation of the silver surface [ 88 ]. For increasing the long-term stability of SERS active silver films we have studied a thin layer of dielectric Al 2 O 3 as protective coating [ 89 ]. A 1 nm thick Al 2 O 3 film was deposited on top of the nanoporous silver film by ALD before adding the probe molecule RhB.…”

Section: Resultsmentioning

confidence: 99%

Controlling surface morphology and sensitivity of granular and porous silver films for surface-enhanced Raman scattering, SERS

Okeil¹,

Schneider²

2018

Beilstein J. Nanotechnol.

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The design of efficient substrates for surface-enhanced Raman spectroscopy (SERS) for large-scale fabrication at low cost is an important issue in further enhancing the use of SERS for routine chemical analysis. Here, we systematically investigate the effect of different radio frequency (rf) plasmas (argon, hydrogen, nitrogen, air and oxygen plasma) as well as combinations of these plasmas on the surface morphology of thin silver films. It was found that different surface structures and different degrees of surface roughness could be obtained by a systematic variation of the plasma type and condition as well as plasma power and treatment time. The differently roughened silver surfaces act as efficient SERS substrates showing greater enhancement factors compared to as prepared, sputtered, but untreated silver films when using rhodamine B as Raman probe molecule. The obtained roughened silver films were fully characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron (XPS and Auger) and ultraviolet–visible spectroscopy (UV–vis) as well as contact angle measurements. It was found that different morphologies of the roughened Ag films could be obtained under controlled conditions. These silver films show a broad range of tunable SERS enhancement factors ranging from 1.93 × 102 to 2.35 × 105 using rhodamine B as probe molecule. The main factors that control the enhancement are the plasma gas used and the plasma conditions, i.e., pressure, power and treatment time. Altogether this work shows for the first time the effectiveness of a plasma treatment for surface roughening of silver thin films and its profound influence on the interface-controlled SERS enhancement effect. The method can be used for low-cost, large-scale production of SERS substrates.

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Section: Resultsmentioning

confidence: 99%

Controlling surface morphology and sensitivity of granular and porous silver films for surface-enhanced Raman scattering, SERS

Okeil¹,

Schneider²

2018

Beilstein J. Nanotechnol.

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“…Enzymatically generated nanoparticles (EGNPs), formed out of flat plates of silver crystals, show a desert‐rose‐ or flower‐like structure and are noted as powerful bottom‐up SERS substrates . These structures have great capability in bioanalytics, e.g., the label‐free detection of plant pathogens or the detection of Sudan III in food matrixes, as shown recently.…”

Section: Resultsmentioning

confidence: 99%

TopUp Plasmonic Arrays for Surface‐Enhanced Raman Spectroscopy

Patze

Huebner

Weber

et al. 2016

Adv Materials Inter

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III in paprika powder, [ 11 ] azorubine in drinks, [ 12 ] or melamine in milk. [ 13 ] In clinical application schemes, SERS shows high potential as a point-of-care method for the online monitoring of morphine, methadone, or dopamine [ 14 ] in intravenous delivery tubing or of levofl oxacin in urine. [ 15 ] Moreover, the detection of environmentally relevant and harmful substances, i.e., arsenic (III) in lake water samples [ 16 ] or veterinary drugs such as metronidazole and ronidazole in various water sources, [ 17 ] extends the application fi eld of SERS. All of the above-mentioned application examples share the enhancement of the naturally weak Raman signal by employing nanostructured metal surfaces, so-called SERS substrates.The applied nanostructured SERS substrates are commonly generated via wet chemistry [ 18 ] and bottom-up [ 19 ] or topdown [ 20,21 ] approaches. Metal colloids can be prepared in large quantities via wet chemical reactions, e.g., the reduction of silver or gold salts to the pure metal. In general, metallic nanoparticle suspensions are characterized by easy handling and fast production in high quantities. In contrast, limitations are related to their low time stability, poor batch-to-batch reproducibility, and spectral interference originating from the reaction participants. As an alternative, laser ablation techniques are employed to fabricate metal nanoparticles without stabilization agents on their surfaces. [ 22 ] Moreover, planar substrates produced by immobilization of metallic nanoparticles based on a bottom-up technique are characterized by low homogeneity across a large area and low batch-to-batch quality.Top-down techniques can overcome some of the above-mentioned limitations by structuring thin metal layers using lithographic techniques, e.g., electron beam lithography (EBL) [ 21,23 ] or nanoimprint lithography (NIL). [ 24 ] These procedures lead to highly homogenous planar substrates with well-defi ned structures and plasmonic resonance tunabilities. However, due to the multiple processing steps required for top-down techniques, the manufacturing time for a given structure is extensive and the process is expensive. Thus, the top-down production of SERS active substrates is realized in small quantities.By an appropriate combination of bottom-up and top-down techniques, the creation of a SERS active substrate that uses the advantages and avoids the drawbacks of each applied fabrication technique becomes feasible. In principle, a sophisticated top-down approach is improved by a fast and easy bottom-up method. As an example, particle-in-cavity structures [ 25 ] were created for which the template (the cavity structure) is fabricated by nanosphere lithography (NSL) [ 25 ] following a porous By combining a bottom-up process with top-down fabricated templates, the benefi ts of both methods are joined by creating so-called TopUp plasmonic arrays for surface-enhanced Raman spectroscopy (SERS). The morphological and optical characterization of the TopUp substrates illustrates exceptional...

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“…with a 10 nm thick Al 2 O 3 protection layer using atomic layer deposition. 39 Preliminary simulations and measurements showed that this layer had negligible influence on the optical properties of the nanoboomerangs, i.e., on the hybridization of the LSPRs. For comparison, we also fabricated elements of a pMS structure using a lift-off process, resulting in nanostructures with a metal strip width of approximately 110 nm and various opening angles and arm lengths.…”

Section: Fabrication and Measurementmentioning

confidence: 97%

Nanoboomerang-based inverse metasurfaces—A promising path towards ultrathin photonic devices for transmission operation

et al. 2017

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Ultra-compact visible chiral spectrometer with meta-lenses APL Photonics 2, 036103 (2017) Metasurfaces have revolutionized photonics due to their ability to shape phase fronts as requested and to tune beam directionality using nanoscale metallic or dielectric scatterers. Here we reveal inverse metasurfaces showing superior properties compared to their positive counterparts if transmission mode operation is considered. The key advantage of such slot-type metasurfaces is the strong reduction of light in the parallel-polarization state, making the crossed-polarization, being essential for metasurface operation, dominant and highly visible. In the experiment, we show an up to four times improvement in polarization extinction for the individual metasurface element geometry consisting of deep subwavelength nanoboomerangs with feature sizes of the order of 100 nm. As confirmed by simulations, strong plasmonic hybridization yields two spectrally separated plasmonic resonances, ultimately allowing for the desired phase and scattering engineering in transmission. Due to the design flexibility of inverse metasurfaces, a large number of highly integrated ultra-flat photonic elements can be envisioned, examples of which include monolithic lenses for telecommunications and spectroscopy, beam shaper or generator for particle trapping or acceleration or sophisticated polarization control for microscopy. © 2017 Author (s)

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Background-Free Bottom-Up Plasmonic Arrays with Increased Sensitivity, Specificity and Shelf Life for SERS Detection Schemes

Cited by 23 publications

References 49 publications

Controlling surface morphology and sensitivity of granular and porous silver films for surface-enhanced Raman scattering, SERS

Controlling surface morphology and sensitivity of granular and porous silver films for surface-enhanced Raman scattering, SERS

TopUp Plasmonic Arrays for Surface‐Enhanced Raman Spectroscopy

Nanoboomerang-based inverse metasurfaces—A promising path towards ultrathin photonic devices for transmission operation

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