2 Interferometric Scattering (iSCAT) Microscopy and Related Techniques
57
way phases, path difference, and index modulations are introduced in the problem.
The main focus of the book chapter has been to discuss the latest developments
of interferometric scattering (iSCAT) microscopy upon the past decade and a half
for detecting, sensing, imaging and tracking nanoparticles [73, 113–116]. Although
the equation describing iSCAT uses very much the same interference expression
known in conventional interferometric microscopy, its application to nanoparticles
was indeed new and has led to a wealth of recent studies. These have often been presented under new acronyms inspired by variations of the illumination and detection
schemes. In this work, we have aimed at unifying these efforts under a common theoretical and experimental roof and have attempted to present a concise discussion of
some case studies and various implementations of iSCAT that are rapidly emerging.
While in its infancy, we believe that iSCAT microscopy stands as an exciting
next-generation tool for uncovering the nanobiology of the cell membrane as well
as advanced diagnostics and laboratory analytics applications. The sensitivity and
performance of iSCAT is only limited by the signal-to-noise ratio, which in turn
depends on factors such as the choice of detector and background fluctuations that
result from specimen dynamics. Advances in detector technologies, image processing
and machine learning, as well as optical techniques for imaging through scattering
media, promise to pave the way to these goals. Thus, we are convinced that the
limits of iSCAT will be continually pushed in the near future, exploring unlabeled
proteins well under 20 kDa not only in a biosensor geometry but also in the living cell
membrane. The simplicity of an iSCAT microscope lends itself to miniaturization into
a compact instrument as well as integration into existing microscope stations such as
a laser scanning confocal microscope, thus providing prospects of very widespread
use.
Acknowledgements We are grateful to a large number of fantastic group members, former and
present, who have contributed to the advances of iSCAT in our laboratories. We also thank the
Alexander von Humboldt Foundation for their generous support in the context of a Humboldt Professorship (VS) and Postdoctoral Fellowship (RWT) as well the Max Planck Society for continuous
support.
References
1. M. Fernández-Suárez, A.Y. Ting, Fluorescent probes for super-resolution imaging in living
cells. Nat. Rev. Mol. Cell Biol. 9(12), 929–943 (2008)
2. E. Abbe, Beiträge zur Theorie des Mikroskops und der mikroskopischen Wahrnehmung. Arch.
Mikrosk. Anat. 9(1), 413–418 (1873)
3. J. Steinhardt, Intensity discrimination in the human eye: I. The relation of I/I to intensity. J.
Gen. Physiol. 20(2), 185–209 (1936)
4. L.C. Martin, B.K. Johnson, Practical Microscopy (Blackie & Son Limited, 1931)
5. J.J. Lister, On some properties in achromatic object-glasses applicable to the improvement of
the microscope. Philos. Trans. R. Soc. Lond. 120, 187–200 (1830)
6. S.H. Gage, Modern dark-field microscopy and the history of its development. Trans. Am.
Microsc. Soc. 39(2), 95–141 (1920)
57
way phases, path difference, and index modulations are introduced in the problem.
The main focus of the book chapter has been to discuss the latest developments
of interferometric scattering (iSCAT) microscopy upon the past decade and a half
for detecting, sensing, imaging and tracking nanoparticles [73, 113–116]. Although
the equation describing iSCAT uses very much the same interference expression
known in conventional interferometric microscopy, its application to nanoparticles
was indeed new and has led to a wealth of recent studies. These have often been presented under new acronyms inspired by variations of the illumination and detection
schemes. In this work, we have aimed at unifying these efforts under a common theoretical and experimental roof and have attempted to present a concise discussion of
some case studies and various implementations of iSCAT that are rapidly emerging.
While in its infancy, we believe that iSCAT microscopy stands as an exciting
next-generation tool for uncovering the nanobiology of the cell membrane as well
as advanced diagnostics and laboratory analytics applications. The sensitivity and
performance of iSCAT is only limited by the signal-to-noise ratio, which in turn
depends on factors such as the choice of detector and background fluctuations that
result from specimen dynamics. Advances in detector technologies, image processing
and machine learning, as well as optical techniques for imaging through scattering
media, promise to pave the way to these goals. Thus, we are convinced that the
limits of iSCAT will be continually pushed in the near future, exploring unlabeled
proteins well under 20 kDa not only in a biosensor geometry but also in the living cell
membrane. The simplicity of an iSCAT microscope lends itself to miniaturization into
a compact instrument as well as integration into existing microscope stations such as
a laser scanning confocal microscope, thus providing prospects of very widespread
use.
Acknowledgements We are grateful to a large number of fantastic group members, former and
present, who have contributed to the advances of iSCAT in our laboratories. We also thank the
Alexander von Humboldt Foundation for their generous support in the context of a Humboldt Professorship (VS) and Postdoctoral Fellowship (RWT) as well the Max Planck Society for continuous
support.
References
1. M. Fernández-Suárez, A.Y. Ting, Fluorescent probes for super-resolution imaging in living
cells. Nat. Rev. Mol. Cell Biol. 9(12), 929–943 (2008)
2. E. Abbe, Beiträge zur Theorie des Mikroskops und der mikroskopischen Wahrnehmung. Arch.
Mikrosk. Anat. 9(1), 413–418 (1873)
3. J. Steinhardt, Intensity discrimination in the human eye: I. The relation of I/I to intensity. J.
Gen. Physiol. 20(2), 185–209 (1936)
4. L.C. Martin, B.K. Johnson, Practical Microscopy (Blackie & Son Limited, 1931)
5. J.J. Lister, On some properties in achromatic object-glasses applicable to the improvement of
the microscope. Philos. Trans. R. Soc. Lond. 120, 187–200 (1830)
6. S.H. Gage, Modern dark-field microscopy and the history of its development. Trans. Am.
Microsc. Soc. 39(2), 95–141 (1920)