Single wavelength reflectometry

from Wikipedia, the free encyclopedia
Reflectivity measurements can be implemented in different ways. 1 : About the change of an extreme point (minimum / maximum) in the x-direction over time. Biolayer Interferometry (BLI), RIfS 2 : About the change in the intensity of a single wavelength in the y-direction

Einwellenlängenreflektometrie ( English single color reflectometry - SCORE ), synonym imaging reflectometric interference (iRIf) and 1-lambda reflectometry is a physical method based on interference of monochromatic light in thin layers, is based. The main area of ​​application of SCORE is (bio) molecular interaction analysis, e.g. B. Protein-protein interactions . Time-resolved binding curves are obtained, which provide information about the kinetic and thermodynamic properties of the observed interaction (s) as well as about the concentration of the analyte used . These (bio) physical properties are of great importance in the pharmaceutical screening of pharmaceuticals and in the design of active ingredients , in biosensors and other biomedical applications, in diagnostics and in cell-based bioassays .

principle

The basic measuring principle corresponds to the Fabry-Pérot interferometer .

1: Monochromatic light is reflected at the phase boundary, 2: when a (bio) molecule is attached, the reflection conditions change, this leads to 3: an increase in intensity due to constructive interference.

realization

Monochromatic light is radiated vertically onto the back of a transparent multilayer system. The incident light is partly transmitted and partly reflected at each interface of the multilayer system . The superposition of the reflected partial beams leads to constructive and destructive interference (depending on the wavelength of the light used and on the materials of the multilayer system used). This interference effect can be recorded as a change in intensity using a photodiode, CCD or CMOS camera.

The sensitive layer on the multilayer system can (bio) chemically with receptor molecules , e.g. B. antibodies , modified. When ligands are specifically bound to these immobilized receptor molecules, the refractive index n and the physical layer thickness d of the sensitive layer change. The product of n and d gives the so-called optical layer thickness ( n · d ) of the sensitive layer.

Exemplary binding curve in the plot of intensity versus time

The change in the intensity of the reflected light during the (bio) molecular interaction over time can be recorded as a so-called binding curve. This contains information about:

  • the concentration of the ligand / analyte used
  • the kinetic constants (association and dissociation rate constants) of receptor-ligand binding
  • the strength of the bond ( affinity ) between receptor and ligand
  • the specificity of the interaction between receptor and ligand

Compared to Bio-Layer Interferometry (BLI), which uses the shift in the interference spectrum during the connection to generate the binding curves, SCORE only records the change in intensity of the reflected light using a photodiode, CCD or CMOS camera. It is therefore not only possible to observe one interaction at a time, but also to analyze up to 10,000 interactions per square centimeter in a spatially resolved manner in high-density arrays. Compared to surface plasmon resonance spectroscopy (SPR), which is limited by the penetration depth of the evanescent field , SCORE is limited in its penetration depth by the coherence wavelength of the light source used. This is usually a few micrometers. This is particularly relevant in bioassays in which whole, living cells are used. Furthermore, the SCORE technology (like the BLI) is not susceptible to interference from temperature changes during the measurement. The SPR technology, on the other hand, requires complex thermostatting, since it detects the change in the refractive index, which is highly temperature-dependent.

Each spot of a microarray results in a time-resolved binding curve.

Applications

This article or the following section is not adequately provided with supporting documents ( e.g. individual evidence ). Information without sufficient evidence could be removed soon. Please help Wikipedia by researching the information and including good evidence.

SCORE is mainly used as a detection method in bio and chemosensors. Like the RIfS, BLI and SPR, it is a label-free technology with which it is possible to detect the binding of analyte molecules to the sensor surface in a time-resolved manner without the need for fluorescence or radioactivity markers.

The SCORE technology was marketed and distributed by Biametrics GmbH, a device manufacturer based in Tübingen, Germany. In January 2020, Biametrics GmbH and its technology were taken over by BioCopy Holding AG, based in Aadorf, Switzerland.

See also

literature

  • Melanie Ewald, Peter Fechner, Günter Gauglitz: A multi-analyte biosensor for the simultaneous label-free detection of pathogens and biomarkers in point-of-need animal testing . In: Analytical and Bioanalytical Chemistry . tape 407 , no. 14 , 2015, ISSN  1618-2642 , p. 4005-4013 , doi : 10.1007 / s00216-015-8562-0 .
  • Oliver Bleher, Aline Schindler, Meng-Xin Yin, Andrew B. Holmes, Peter B. Luppa, Günter Gauglitz, Günther Proll: Development of a new parallelized, optical biosensor platform for label-free detection of autoimmunity-related antibodies . In: Analytical and Bioanalytical Chemistry . tape 406 , no. 14 , 2014, ISSN  1618-2642 , p. 3305-3314 , doi : 10.1007 / s00216-013-7504-y .
  • Aline R. Schindler, Oliver Bleher, Markus A. Thaler, Carmen J. Kocot, Udo Steigerwald, Günther Proll, Günter Gauglitz, Peter B. Luppa: Diagnostic performance study of an antigen microarray for the detection of antiphospholipid antibodies in human serum . In: Clinical Chemistry and Laboratory Medicine (CCLM) . tape 53 , no. 5 , 2015, ISSN  1437-4331 , doi : 10.1515 / cclm-2014-0569 .
  • Melanie Ewald, Alexander Fabian Le Blanc, Günter Gauglitz, Günther Proll: A robust sensor platform for label-free detection of anti-Salmonella antibodies using undiluted animal sera . In: Analytical and Bioanalytical Chemistry . tape 405 , no. 20 , 2013, ISSN  1618-2642 , p. 6461-6469 , doi : 10.1007 / s00216-013-7040-9 .
  • Rüdiger Frank, Bernd Möhrle, Dieter Fröhlich, Günter Gauglitz: A transducer-independent optical sensor system for the detection of biochemical binding reactions . tape 5993 . International Society for Optics and Photonics, 2005, p. 59930A , doi : 10.1117 / 12.633881 .
  • Juergen Burger, Christin Rath, Johannes Woehrle, Philipp A. Meyer, Nessim Ben Ammar, Normann Kilb, Thomas Brandstetter, Florian Pröll, Guenther Proll, Gerald Urban, Guenter Roth: Low-Volume Label-Free Detection of Molecule-Protein Interactions on Microarrays by Imaging Reflectometric Interferometry . In: SLAS TECHNOLOGY: Translating Life Sciences Innovation . tape 22 , no. 4 , 2016, p. 437-446 , doi : 10.1177 / 2211068216657512 .

Web links

Individual evidence

  1. ↑ Alice Mueller, Peter Fechner, Hans Michael Maric, Claus Schafer-Nielsen, Florian Pröll, Günther Proll: Simultaneous label-free analysis of 1485 antibody-antigen interactions . Poster. June 17, 2017 ( biametrics.com [PDF; accessed November 16, 2017]).