Jump to content

Holotomography

From Wikipedia, the free encyclopedia

This is an old revision of this page, as edited by Nemo bis (talk | contribs) at 13:47, 19 July 2019 (redundant URL). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.

Holotomography (HT) is a laser technique to measure three-dimensional refractive index (RI) tomogram of a microscopic sample such as biological cells and tissues. Because the RI can serve as an intrinsic imaging contrast for transparent or phase objects, measurements of RI tomograms can provide label-free quantitative imaging of microscopic phase objects. In order to measure 3-D RI tomogram of samples, HT employs the principle of holographic imaging and inverse scattering. Typically, multiple 2D holographic images of a sample are measured at various illumination angles, employing the principle of interferometric imaging. Then, a 3D RI tomogram of the sample is reconstructed from these multiple 2D holographic images by inversely solving light scattering in the sample.

The principle of HT is very similar to X-ray computed tomography (CT) or CT scan. CT scan measures multiple 2-D X-ray images of a human body at various illumination angles, and a 3-D tomogram (X-ray absorptivity) is then retrieved via the inverse scattering theory. Both the X-ray CT and laser HT shares the same governing equation – Helmholtz equation, the wave equation for a monochromatic wavelength. HT is also known as optical diffraction tomography.[1]

Applications

The applications of HT includes[2]

3D RI tomogram of a live cell (macrophage)

Cell biology

HT provides 3D dynamic images of live cells and thin tissues without using exogenous labeling agents such as fluorescence proteins or dyes. HT enables quantitative live cell imaging, and also provides quantitative information such as cell volume, surface area, protein concentration. HT provides following advantages over conventional 3D microscopic techniques.

  1. Label-free: Cellular membrane and subcellular organelles can clearly be imaged without using exogenous labeling agents. Thus, there are no issues of phototoxicity, photobleaching, and photodamaging.
  2. Quantitative imaging capability: HT directly measures cell’s 3D RI maps, which is intrinsic optical properties of materials. Because the measured RI can be translated into the mass density of a cell and using this information, mass of a cell can also be retrieved.
  3. Precise and fast measurements: HT provides the spatial resolution down to approximately 100 nm and the temporal resolution of a few to a hundred frames per second, depending on the numerical apertures of used objective lenses and the speed of an image sensor.

However, 3D RI tomography does not provide molecular specificity. Generally, the measured RI information cannot be directly related to information about molecules or proteins, except for notable cases such as gold nanoparties[3] or lipid droplets[4] that exhibit distinctly high RI values compared to cell cytoplams.

Experimental Laboratory

HT provide various quantitative imaging capability, providing morphological, biochemical, and mechanical properties of individuals cells. 3D RI tomography directly provides morphological properties including volume, surface area, and sphericity (roundness) of a cell. Local RI value can be translated into biochemical information or cytoplasmic protein concentration, because the RI of a solution is linearly proportional to its concentration.[5] In particular, for the case of red blood cells, RI value can be converted into hemoglobin concentration. Measurements of dynamic cell membrane fluctuation, which can also be obtained with a HT instrument, provides information about cellular deformability. Furthermore, these various quantitative parameters can be obtained at the single cell level, allowing correlative analysis between various cellular parameters. HT has been utilized for the study of red blood cells,[6] white blood cells,[7] malaria infection,[8] bebasia infection,[9] blood storage,[10] and diabetes.[11]

History

The first theoretical proposal was presented by Emil Wolf,[12] and the first experimental demonstration was shown by Fercher et al.[13] From 2000s, HT techniques had been extensively studied and applied to the field of biology and medicine, by several research groups including the MIT spectroscopy laboratory. Both the technical developments and applications of HT have been significantly advanced. During the mid 2010s, first commercial HT companies Nanolive and Tomocube were founded.

See also

References

  1. ^ Lauer, V (2002). "New approach to optical diffraction tomography yielding a vector equation of diffraction tomography and a novel tomographic microscope". Journal of Microscopy. 205 (2): 165–176. doi:10.1046/j.0022-2720.2001.00980.x.
  2. ^ Park, YongKeun (2018). "Quantitative phase imaging in biomedicine". Nature Photonics. 12 (10): 578–589. Bibcode:2018NaPho..12..578P. doi:10.1038/s41566-018-0253-x.
  3. ^ Kim, Doyeon (2016). "Label-free high-resolution 3-D imaging of gold nanoparticles inside live cells using optical diffraction tomography". bioRxiv 097113. {{cite bioRxiv}}: Check |biorxiv= value (help)
  4. ^ Kim, Kyoohyun (2016). "Three-dimensional label-free imaging and quantification of lipid droplets in live hepatocytes". Scientific Reports. 6: 36815. arXiv:1611.01774. Bibcode:2016NatSR...636815K. doi:10.1038/srep36815.
  5. ^ Baber, R. (1952). "Interference microscopy and mass determination". Nature. 169 (4296): 366–7. Bibcode:1952Natur.169..366B. doi:10.1038/169366b0. PMID 14919571.
  6. ^ Park, YongKeun (2010). "Measurement of red blood cell mechanics during morphological changes". PNAS. 107 (15): 6731–6. Bibcode:2010PNAS..107.6731P. doi:10.1073/pnas.0909533107. PMC 2872375. PMID 20351261.
  7. ^ Yoon, Jonghee (2015). "Label-free characterization of white blood cells by measuring 3D refractive index maps". Biomedical Optics Express. 6 (10): 3865–75. doi:10.1364/BOE.6.003865. PMC 4605046. PMID 26504637.
  8. ^ Park, YongKeun (2008). "Refractive index maps and membrane dynamics of human red blood cells parasitized by Plasmodium falciparum". PNAS. 105 (37): 13730–13735. Bibcode:2008PNAS..10513730P. doi:10.1073/pnas.0806100105. PMC 2529332. PMID 18772382.
  9. ^ HyunJoo, Park (2015). "Characterizations of individual mouse red blood cells parasitized by Babesia microti using 3-D holographic microscopy". Scientific Reports. 5: 10827. arXiv:1505.00832. Bibcode:2015NatSR...510827P. doi:10.1038/srep10827. PMC 4650620. PMID 26039793.
  10. ^ Park, Hyunjoo (2016). "Measuring cell surface area and deformability of individual human red blood cells over blood storage using quantitative phase imaging". Scientific Reports. 6: 34257. Bibcode:2016NatSR...634257P. doi:10.1038/srep34257. PMC 5048416. PMID 27698484.
  11. ^ Lee, SangYun (2017). "Refractive index tomograms and dynamic membrane fluctuations of red blood cells from patients with diabetes mellitus". Scientific Reports. 7 (1): 1039. Bibcode:2017NatSR...7.1039L. doi:10.1038/s41598-017-01036-4. PMC 5430658. PMID 28432323.
  12. ^ Wolf, Emil (1969). "Three-dimensional structure determination of semi-transparent objects from holographic data". Optics Communications. 1 (4): 153–156. Bibcode:1969OptCo...1..153W. doi:10.1016/0030-4018(69)90052-2.
  13. ^ Fercher, A.F.; Bartelt, H.; Becker, H.; Wiltschko, E. (1979). "Image formation by inversion of scattered field data: experiments and computational simulation". Applied Optics. 18 (14): 2427–39. Bibcode:1979ApOpt..18.2427F. doi:10.1364/AO.18.002427. PMID 20212679.
Retrieved from "https://en.wikipedia.org/w/index.php?title=Holotomography&oldid=906960091"