zero-mode waveguide is an
optical waveguide
An optical waveguide is a physical structure that guides electromagnetic waves in the optical spectrum. Common types of optical waveguides include optical fiber waveguides, transparent dielectric waveguides made of plastic and glass, liquid light ...
that guides light energy into a volume that is small in all dimensions compared to the
wavelength
In physics, the wavelength is the spatial period of a periodic wave—the distance over which the wave's shape repeats.
It is the distance between consecutive corresponding points of the same phase on the wave, such as two adjacent crests, tr ...
of the light.
Zero-mode waveguides have been developed for rapid parallel sensing of
zeptolitre sample volumes, as applied to
gene sequencing Gene Sequencing may refer to:
* DNA sequencing
* or a comprehensive variant of it: Whole genome sequencing
Whole genome sequencing (WGS), also known as full genome sequencing, complete genome sequencing, or entire genome sequencing, is the pr ...
, by
Pacific Biosciences
Pacific Biosciences of California, Inc. (aka PacBio) is an American biotechnology company founded in 2004 that develops and manufactures systems for gene sequencing and some novel real time biological observation. PacBio describes its platform ...
(previously named Nanofluidics, Inc.)
A waveguide operated at frequencies lower than its
cutoff frequency
In physics and electrical engineering, a cutoff frequency, corner frequency, or break frequency is a boundary in a system's frequency response at which energy flowing through the system begins to be reduced ( attenuated or reflected) rather tha ...
(wavelengths longer than its
cutoff wavelength
In physics and electrical engineering, a cutoff frequency, corner frequency, or break frequency is a boundary in a system's frequency response at which energy flowing through the system begins to be reduced ( attenuated or reflected) rather than ...
) and used as a precision
attenuator is also known as a "waveguide below-cutoff attenuator."
The zero-mode waveguide is made possible by creating circular or rectangular nanoapertures using
focused ion beam on an aluminium layer.
The zero-mode waveguide can also enhance fluorescence signals due to surface plasmon generated at metal-dielectric interfaces. Due to surface plasmon generation field is localized and enhanced as well as it changes the LDOS inside the cavity which leads to increase in Purcell Factor of analyte molecules inside the zero-mode waveguide
The zero-mode waveguide is very useful for Ultraviolet Auto-fluorescence spectroscopy on tryptophan-carrying proteins like beta-galactosidase
with further modification of the zero-mode waveguide with a conical reflector its possible to study the dynamic process of smaller proteins like streptavidin with 24 tryptophan.
,
The modified zero-mode waveguide with a conical reflector can be further optimized to enhance the Signal-to-noise ratio and reach the ultimate sensitivity of single tryptophan proteins like TNase.
See also
*
Single molecule real-time sequencing
References
Biophysics
Physical optics
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