Performing tip‐enhanced Raman spectroscopy in liquids

Schmid, Thomas; Yeo, Boon Siang; Leong, Grace; Stadler, Johannes; Zenobi, Renato

doi:10.1002/jrs.2387

Cited by 159 publications

(185 citation statements)

References 53 publications

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“…Thus, electromagnetic enhancement is resulted for the incident excitation field and the emitted Raman signal for R6G molecules in close vicinity to the Ag surface. The AEF value of 2 Â 10 4 achieved in case of the Ag coated microneedle is comparable to that reported [21] in a different experimental setup in which about an enhancement factor of 10 4 was achieved using a Agcoated tip. Our Ag-coated microneedle-based SERS probe allows direct SERS measurements of analyte molecules in phantoms without the introduction of nanoparticles or the requirement of removing the needle for testing, although at an expense of a reduced AEF due to light absorption and scattering in the phantom layers.…”

Section: Resultssupporting

confidence: 85%

Towardsin vivointradermal surface enhanced Raman scattering (SERS) measurements: silver coated microneedle based SERS probe

Yuen

Liu

2013

Journal of Biophotonics

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Journal of BIOPHOTONICSWe propose a microneedle coated with silver (Ag) to detect analytes at low concentrations positioned at a depth of more than 700 mm below the surface of a skin phantom with absorbers and scatterers for mimicking the intradermal surface-enhanced Raman scattering (SERS) measurements. The Ag layer in the Ag-coated microneedle-based probe is found to be the key to the effective detection of analytes buried inside the aforesaid phantom. Glucose concentrations ranging from 5 to 150 mM inside phantoms can be estimated with a root mean square error (RMSE) of 3.3 mM. This work shows the potential of using microneedles for simple in vivo intradermal SERS measurements of analytes with clinical relevance.SERS spectra of R6G molecules positioned inside the bottom layer of an agar phantom at a depth of 760 mm below the surface (inset) measured by using Ag-coated microneedle (conc: 10 -4 M; P EX : 5 mW), microneedle (conc: 10 -2 M; P EX : 5 mW), and ordinary Raman (conc: 10 -2 M; P EX : 100 mW). P EX means the excitation power and conc means concentration of R6G in the bottom layer.

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Section: Resultssupporting

confidence: 85%

Towardsin vivointradermal surface enhanced Raman scattering (SERS) measurements: silver coated microneedle based SERS probe

Yuen

Liu

2013

Journal of Biophotonics

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“…TERS has also been attempted in liquids, which would be very beneficial for measuring biological systems in more realistic environments [377]. TERS in liquid may actually solve some problems such as providing a heat-sink for tip-induced sample heating.…”

Section: Applicationsmentioning

confidence: 99%

Raman spectroscopy: techniques and applications in the life sciences

Shipp¹,

Sinjab²,

Notingher³

2017

Adv. Opt. Photon.

232

180

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Raman spectroscopy is an increasingly popular technique in many areas including biology and medicine.It is based on Raman scattering, a phenomenon in which incident photons lose or gain energy via interactions with vibrating molecules in a sample. These energy shifts can be used to obtain information regarding molecular composition of the sample with very high accuracy. Applications of Raman spectroscopy in the life sciences have included quantification of biomolecules, hyperspectral molecular imaging of cells and tissue, medical diagnosis, and others. This review briefly presents the physical origin of Raman scattering explaining the key classical and quantum mechanical concepts. Variations of the Raman effect will also be considered, including resonance, coherent, and enhanced Raman scattering. We discuss the molecular origins of prominent bands often found in the Raman spectra of biological samples. Finally, we examine several variations of Raman spectroscopy techniques in practice, looking at their applications, strengths, and challenges. This review is intended to be a starting resource for scientists new to Raman spectroscopy, providing theoretical background and practical examples as the foundation for further study and exploration.

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“…The tip stability over time was not the aim of their studies, however, they showed that SAMs can provide protection against carbon and other tip contaminants. They also determined that the enhancement dropped by approximately a factor of 5 due to the coating [8].…”

Section: Introductionmentioning

confidence: 99%

“…To the best of our knowledge, the Zenobi group [7,8] have provided the only successful report in TERS literature regarding self-assembled monolayers (SAMs) utilized of ethanethiol and thiophenol on the tips. They employed ethanethiol SAMs to protect the surface of a silver probe for TERS in liquid conditions.…”

Section: Introductionmentioning

confidence: 99%

Chemical stability of plasmon-active silver tips for tip-enhanced Raman spectroscopy

Kalbacova¹,

Rodriguez²,

Desale³

et al. 2015

Nanospectroscopy

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Silver nanostructures are used in tip- and surface-enhanced Raman spectroscopy due to their high electric field enhancement over almost the entire visible spectral range. However, the low chemical stability of silver, compared to other noble metals, promotes silver sulfide and sulfate formation which decreases its plasmonic activity. This is why silver tips are usually prepared on the same day of the experiments or are disregarded in favour of gold that is chemically more stable. Since silver degradation cannot be avoided, we hypothesized that a protection layer may be able to minimize or control degradation. In this contribution, we report the successful preparation of 4-biphenylthiol and 4’-nitro-4-biphenylthiol self-assembled monolayers on silver tips in order to protect them against tarnishing and to investigate the effect on the life-time of the plasmonic activity. The electrochemically etched wire surface was probed via Raman spectroscopy and scanning electron microscopy. The best long term stability and resistance against corrosion was shown by a monolayer of 4-biphenylthiol formed from dimethylformamide which did not display any degradation of the metallic tip during the observed period. Here, we demonstrate an easy and straightforward approach towards increasing the chemical stability of silver TERS-active probes.

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Performing tip‐enhanced Raman spectroscopy in liquids

Cited by 159 publications

References 53 publications

Towardsin vivointradermal surface enhanced Raman scattering (SERS) measurements: silver coated microneedle based SERS probe

Towardsin vivointradermal surface enhanced Raman scattering (SERS) measurements: silver coated microneedle based SERS probe

Raman spectroscopy: techniques and applications in the life sciences

Chemical stability of plasmon-active silver tips for tip-enhanced Raman spectroscopy

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