Tip-enhanced Raman spectroscopy and related techniques in studies of biological materials

Schmid, Thomas; Sebesta, Aleksandar; Stadler, Johannes; Opilik, Lothar; Balabin, Roman M.; Zenobi, Renato

doi:10.1117/12.845471

Cited by 14 publications

(14 citation statements)

References 43 publications

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“…In the actual combination of objective lens and laser scanner, the measurement area for Raman imaging is restricted to 76 × 76 µm 2 . Because of an 80‐µm‐wide confocal pinhole in front of the spectrometer, the detected spectra originate from a sample volume restricted to <1 µm 3 (approximately 500 nm lateral and 1 µm depth resolution) even in cases where light scattering blurs the laser spot. For the shown spectra, no background correction or any other form of data processing has been performed.…”

Section: Methodsmentioning

confidence: 99%

Determination and imaging of binder remnants and aggregates in historic cement stone by Raman microscopy

Schmid

Dariz

2013

J Raman Spectroscopy

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We present to our knowledge the first application of Raman microscopic imaging to cementitious materials. This technique yielded the composition and phase distribution (spatial resolution % 500 nm) in samples of cement stone taken from façade elements of four Swiss buildings covering the period of 1892-1924. Raman maps of Roman cement, a predecessor of modern Portland cement, reveal the chemical heterogeneity of clinker remnants consisting of various crystalline, polymorphic, and amorphous phases and visualize different crystal orientations. Our findings include the observation of the g-polymorph of Ca 2 SiO 4 -previously, only detected in Portland cement -and Raman spectra of calcium aluminate (ferrite) interstitial phases in Roman cement showing significant differences to the corresponding phases in Portland cement clinker. Furthermore, calcite, vaterite, gypsum, and ettringite were identified in the rim of a nonhydrated residual nodule. Beyond binder remnants, aggregates in the form of spherical (≤500 mm diameter) slag and irregularly shaped pigment particles were analyzed. Here, we focused on the unambiguous identification of compounds in complex matrices by comparing sample spectra with database and own reference spectra. A Raman map collected on blast furnace slag in cement stone shows the spatial distribution of calcite, quartz glass and pyrite. Furthermore, several Fe-containing, Si-containing, and Pb-containing phases were identified. The analysis of pigments partly confirmed and partly contradicted the bequeathed historic recipe of a cement stone façade. These results have direct implications in the field of conservation and restoration and generally demonstrate the potential of Raman imaging to provide deeper understanding of (historic) building materials.

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Section: Methodsmentioning

confidence: 99%

Determination and imaging of binder remnants and aggregates in historic cement stone by Raman microscopy

Schmid

Dariz

2013

J Raman Spectroscopy

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“…Raman microscopy analyses (Schmid et al, 2010) were carried out on ultrathin sections previously studied by TEM, using an upright NTegra SPECTRA system (NT-MDT, Zelenograd ⁄ Moscow, Russia) equipped with a white-light microscope module for sample observation and a confocal laser microscope. Measurements were performed using a 632.8-nm laser for excitation (laser powers at the sample: 0.1-1 mW).…”

Section: Methodsmentioning

confidence: 99%

Cretaceous black shale: a window into microbial life adaptation

et al. 2011

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Terra Nova, 23, 362–368, 2011 Abstract As bacteria are usually incompletely preserved in the geological record, their recognition can only be based on their degradation‐resistant cell walls. However, the latter provide no indication about conditions occurring before the death of the bacteria. In this article, we attempt to demonstrate the syngenecity of bacteria found in the Albian oceanic anoxic event (OAE1b) from the Urbino level and highlight their physiology from their possible intracellular components. Dark storage inclusions have been identified as inorganic polyphosphate, in addition to carotenoids which have been encountered in the cell. Before death, stress and deprivation resulted in drastic changes in physiology generating properties such as regulatory functions of polyphosphates and the ability of carotenoids to rigidify membranes. Therefore, this starvation strategy induced a more resistant state possibly enhancing the preservation of these bacteria. These results demonstrate the potential for exploring indications of past microbial life in other black shales.

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“…Both excitation and collection of backscattered light are performed with a 100× long-working-distance objective with a numerical aperture (NA) of 0.7. A 532 nm diode pumped solid state laser is used for Raman microscopy and spectroscopy [19,24]. The applied laser power depends on the sample.…”

Section: Instrumentationmentioning

confidence: 99%

“…Most reports indicate that Au-or Agmetalized AFM tips enhance Raman signals by times up to 3.5 [5,18]. Meanwhile, the chemical sensitivity and reproducibility of AFM-TERS needs to be further improved in virtue of amelioration of metalized AFM tip [19,20]. This remains a challenging work [9,21].…”

Section: Introductionmentioning

confidence: 96%

Si@Cu@Au AFM tips for tip-enhanced Raman spectrum

Lü

Wang

et al. 2015

Sci. China Chem.

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Tip-enhanced Raman spectrum (TERS) is a scanning probe technique for acquiring chemical information at high spatial resolution and with high chemical sensitivity. The sensitivity of TERS with atomic force microscopy (AFM) system is mainly determined by the metalized tips. Here, we report a fabrication protocol for AFM-TERS tips that incorporate a copper (Cu) primer film between a gold (Au) layer and a Si AFM tips. They were fabricated by coating the Si tip with a 2 nm Cu layer prior to adding a 20 nm Au layer. For top illumination TERS experiments, these tips exhibited superior TERS performance relative to that observed for tips coated with Au only. Samples included graphene, thiophenol and brilliant cresyl blue. The results may derive from the surface roughness of the tip apex and a Cu/Au synergism of local surface plasmon resonances. tip enhanced Raman spectrum, metalized tip, graphene, thiophenol, brilliant crystal blue

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Tip-enhanced Raman spectroscopy and related techniques in studies of biological materials

Cited by 14 publications

References 43 publications

Determination and imaging of binder remnants and aggregates in historic cement stone by Raman microscopy

Determination and imaging of binder remnants and aggregates in historic cement stone by Raman microscopy

Cretaceous black shale: a window into microbial life adaptation

Si@Cu@Au AFM tips for tip-enhanced Raman spectrum

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