Nanosampling via Internal Reflection Spectroscopy

Harrick, N. J.

doi:10.1366/0003702874868052

Cited by 117 publications

(140 citation statements)

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“…[16][17][18] In this setup, the IR light is reflected at the interface of a crystal (most commonly diamond, ZnSe, or Ge) and the sample. Since, in this process, an evanescent wave penetrates only a few mm into the sample, the protein film can be much thicker than in the transmittance cell.…”

Section: Methodsmentioning

confidence: 99%

Proteins in Action Monitored by Time‐Resolved FTIR Spectroscopy

2005

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In the post genome era proteins coming into the focus of life sciences. X‐ray structure analysis and NMR spectroscopy are established methods to determine the geometry of proteins. In order to determine the molecular reaction mechanism of proteins, time‐resolved FTIR (trFTIR) difference spectroscopy emerges as a valuable tool. In this Minireview we describe the trFTIR difference spectroscopy and show its application on the light‐driven proton pump bacteriorhodopsin (bR), the photosynthetic reaction center and the GTPase Ras, which is crucial in signal transduction. The main principles of the technique are presented, including a summary of triggering techniques, scan modes and analysis.

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Section: Methodsmentioning

confidence: 99%

Proteins in Action Monitored by Time‐Resolved FTIR Spectroscopy

2005

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“…Absorption in the metal layer influences significantly the width of the reflectance dip ΔR [41][42][43]. Since the dissipation in metals is determined mainly by the imaginary part of the refractive index n mi , one may choose a metal type with low imaginary part to reduce the dissipation and consequently to obtain a narrower dip.…”

Section: Metal-layer Optimizationmentioning

confidence: 99%

Sensitivity‐enhancement methods for surface plasmon sensors

Shalabney

Abdulhalim

2011

Laser & Photonics Reviews

453

254

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Surface plasmon resonance (SPR) sensors have been a mature technology for more than two decades now, however, recent investigations show continuous enhancement of their sensitivity and their lower detection limit. Together with the recent investigations in localized SPR phenomena, extraordinary optical transmission through nanoapertures in metals, and surface-enhanced spectroscopies, drastic developments are expected to revolutionize the field of optical biosensing. Sensitivity-enhancement (SE) techniques are reviewed focusing both on the physical transduction mechanisms and the system performance. In the majority of cases the SE is associated with the enhancement of the electromagnetic field overlap integral describing the interaction energy within the analyte. Other important mechanisms are the interaction between plasmons and excitons and between the analyte molecules and the metal surface. The lower detection limit can be reduced significantly if systems with high signal-to-noise ratio are used such as common-path interferometry, ellipsometry or polarimetry systems.

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“…Since the evanescent field decays exponentially away from the interface, an ATR measurement only picks up signals within a few microns from the IRE, depending on angle of incidence and the ratio of the refractive index of the IRE and the contacting media. [5,8] Multiple-bounce ATR-FTIR spectroscopy increases the sensitivity by increasing the sampling area ( N enhancement for N multiple bounces). Recent developments of high-pressure contact ATR instruments using, for example, diamond IRE now allow for routine analysis of powders, fibres or textiles which otherwise have an inherently small contact area with flat IREs.…”

Section: Introductionmentioning

confidence: 99%

“…(7) and (8) in the Experimental Section], it is customary to introduce the surface concentration, G = (c s d)/1000 (mol cm À2 ), which is related to the integrated absorption as shown in Equation (3): [7,12,30] G…”

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confidence: 99%

A Novel ATR‐FTIR Approach for Characterisation and Identification of Ex Situ Immobilised Species

et al. 2007

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We demonstrate a novel method to analyse ex situ prepared protein chips by attenuated total reflection Fourier IR spectroscopy (ATR‐FTIR), which circumvents tedious functionalisation steps of internal reflection elements (IREs), and simultaneously allows for complementary measurements by other analytical techniques. This concept is proven by utilising immobilised metal affinity capture (IMAC™) chips containing about 10 μm thick films of copolymers coated with nitrilotriacetic acid (NTA) groups, which originally was manufactured for surface enhanced laser desorption ionisation (SELDI) spectrometry. Three immobilisation steps were analysed by ATR‐FTIR spectroscopy: 1) NTA complexation with nickel(II) ions 2) binding of two histidine (His)‐tagged synthetic peptides of 25 (25‐His6) and 48 (48‐His6) amino acids to the NTA‐groups and 3) attachment of a ligand, mesyl amide, to the surface‐bound 48‐His6. Despite interference from H2O, both amide I and II were well resolved. Utilising peptide adsorption in the thick copolymer matrix yields a high saturation peptide concentration of ≈100 mg mL−1 and a dissociation constant of 116±11 μM, as determined by a detailed analysis of the Langmuir adsorption isotherm. The mesyl amide ligand was directly seen in the raw ATR‐FTIR spectrum with specific peaks in the fingerprint region at 1172 and 1350 cm−1. Several aspects of the fine structure of the amide I band of the peptide were analysed: influences from secondary structure, amino side chains and competing contamination product. We believe that this approach has great potential as a stand‐alone or complementary analytical tool for determination of the chemical composition of functionalised surfaces. We emphasise further that with this approach no chemical treatment of IREs is needed; the chips can be regenerated and reused, and applied in other experimental set‐ups.

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Nanosampling via Internal Reflection Spectroscopy

Cited by 117 publications

References 1 publication

Proteins in Action Monitored by Time‐Resolved FTIR Spectroscopy

Proteins in Action Monitored by Time‐Resolved FTIR Spectroscopy

Sensitivity‐enhancement methods for surface plasmon sensors

A Novel ATR‐FTIR Approach for Characterisation and Identification of Ex Situ Immobilised Species

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