Researchers detect coronavirus particles with 'slow light'
The novel detection platform is fast, accurate, and performs label-free imaging of virus particles by slowing down light

Date:
April 21, 2022
Source:
GIST (Gwangju Institute of Science and Technology)
Summary:
Existing methods for detecting and diagnosing COVID-19 are either
expensive and complex or inaccurate. Now, scientists have developed
a novel biosensing platform to detect and quantify viral particles
using a simple optical microscope and antibody proteins. Their
versatile approach, based on slowing down light, could pave the
way to new diagnostic tools and next-generation detection platforms
that are fast, accurate, and low-cost.



FULL STORY ========================================================================== Existing methods for detecting and diagnosing COVID-19 are either
expensive and complex or inaccurate. Now, scientists from the Gwangju
Institute of Science and Technology have developed a novel biosensing
platform to detect and quantify viral particles using a simple optical microscope and antibody proteins. Their versatile approach, based on
slowing down light, could pave the way to new diagnostic tools and next-generation detection platforms that are fast, accurate, and low-cost.


========================================================================== Despite all the bad news the COVID-19 pandemic brought upon the world,
it has helped us gain a better perspective of our readiness to fend off
highly contagious diseases. Rapid diagnostic test kits and PCR testing
quickly became essential tools when the pandemic hit, helping with timely diagnoses. However, these tools have inherent limitations. PCR tests are complex and require expensive equipment while rapid diagnostic test kits
have lower accuracy.

Against this backdrop, a research group led by Professor Young Min Song
of the Gwangju Institute of Science and Technology in Korea has recently developed a new technique to easily visualize viruses using an optical microscope. A recent study explains in detail the operating principle of
their detection platform, called the "Gires-Tournois immunoassay platform" (GTIP). This paper was made available online on March 22, 2022, and was published in the journal Advanced Materials on March 26, 2022.

The key element of GTIP is the Gires-Tournois "resonance structure," a
film made from three stacked layers of specific materials that produce a peculiar optical phenomenon called "slow light." Because of how incident
light rebounds inside the resonant layers before being reflected, the
color of the platform seen through an optical microscope appears very
uniform. However, nanometer- sized virus particles affect the resonance frequency of GTIP in their immediate vicinity by slowing down the light
that gets reflected around them. The "slow light" manifests as a vivid
color change in the reflected light so that, when viewed through the microscope, the virus particle clusters look like "islands" of a different color compared to the background.

To ensure that their system only detects coronavirus particles, the
researchers coated the top layer of GTIP with antibody proteins specific
to SARS-CoV-2.

Interestingly, not only did the system enable the detection of viral
particles, but, by using colorimetric analysis techniques, the researchers could even effectively quantify the number of virus particles present
in different areas of a sample depending on the color of the light
reflected locally.

The overall simplicity of the design is one of the main selling points
of GTIP.

As Prof. Song explains, "Compared to existing COVID-19 diagnostic
methods, our approach enables rapid detection and quantification of
SARS-CoV-2 without needing extra sample treatments, such as amplification
and labeling." Given that optical microscopes are available in most laboratories, the method developed by the group could become a valuable
and ubiquitous diagnostic and virus research tool.

Furthermore, GTIP is not limited to detecting viruses or strictly
dependent on antibodies; any other binding agent works as well, helping visualize all kinds of particles that interact with light. "Our strategy
can even be applied for a dynamic monitoring of target particles sprayed
in the air or dispersed on surfaces. We believe that this approach could
be the basis for next-generation biosensing platforms, enabling simple
yet accurate detection," concludes Prof.

Song.


========================================================================== Story Source: Materials provided by GIST_(Gwangju_Institute_of_Science_and_Technology). Note: Content may
be edited for style and length.


========================================================================== Journal Reference:
1. Young Jin Yoo, Joo Hwan Ko, Gil Ju Lee, Jiwon Kang, Min Seok Kim,
Stefan
G. Stanciu, Hyeon‐Ho Jeong, Dae‐Hyeong Kim, Young
Min Song.

Gires-Tournois Immunoassay Platform for Label‐Free
Bright‐Field Imaging and Facile Quantification of
Bioparticles.

Advanced Materials, 2022; 2110003 DOI: 10.1002/adma.202110003 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/04/220421094151.htm

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