Light-based device uses a few drops of saliva to effectively test COVID-
19 patients

Date:
February 22, 2022
Source:
ICFO-The Institute of Photonic Sciences
Summary:
Researchers report on the development of a low-cost, portable,
non- invasive device that uses light and saliva to test COVID-19
patients in less than 30 minutes. The results have shown that
the device can detect very low concentrations of SARS-CoV-2 with
a sensitivity of 91.2 percent and a specificity of 90 percent,
similar to that of PCR but as fast as an antigen test.



FULL STORY ==========================================================================
A team of researchers from ICFO and IrsiCaixa report on the development
of a low-cost, portable, non-invasive device that uses light and saliva
to test Covid-19 patients in less than 30 minutes. The results have
shown that the device can detect very low concentrations of SARS-CoV-2
with a sensitivity of 91.2% and a specificity of 90%, similar to that
of PCR but as fast as an antigen test.


==========================================================================
The breakout of Covid-19 became a game changer in the medical field
in 2020.

Studies bloomed and steered into full motion to try and find solutions
via different paths; on one hand, vaccinations to control the spread
of the disease, and on the other hand, seeking for testing techniques
that could be available and accessible to everyone around the globe. At
the beginning, PCRs were one of the few available techniques capable
of providing accurate results, but this technique was expensive and it
required specialized personnel and equipment to carry them out. Due to the increasing demand of tests, antigen testing then became an alternative
that was much faster and cheaper, but less reliable since it was less
sensitive than the former.

In a recent study published in Biomedical Optics Express, ICFO
researchers Rubaiya Hussain, Alfredo E. Ongaro, Ewelina Wajs, led by
ICREA Prof. Valerio Pruneri, in collaboration with researchers Maria
L. Rodriguez De La Concepcio'n, Eva Riveira-Mun~oz, Ester Ballana,
Julia` Blanco, Ruth Toledo, Anna Chamorro, Marta Massanella, Lourdes
Mateu, Eulalia Grau, Bonaventura Clotet, led by Jorge Carrillo from
IrsiCaixa AIDS Research Institute, have demonstrated and developed a
novel technology capable of providing fast and reliable detection of
SARS-CoV-2 in saliva samples for COVID-19 testing. The team achieved
a detection limit much lower than the antigen tests and when carried
out a blind test on more than 50 patients, they obtained results with
a sensitivity of 91.2% and a specificity of 90%.

The need Working daily with COVID-19 patients, Marisa Rodriguez
and Jorge Carrillo, researchers at IrsiCaixa, remember that "at the
beginning of the pandemic we knew it was really important to detect all
those infected individuals in order to control the virus spread. That's
why IrsiCaixa researchers, with Bonaventura Clotet at the helm of the initiative, got together and saw the need to find an alternative to PCR
and antigen tests that would combine the advantages of each of them, and
that would also detect SARS-CoV-2 infection from saliva samples as it
is much simpler and less invasive to obtain for most patients.." With
this idea in mind, they contacted ICFO seeking for the technology
for light-based imaging and diagnosis devices, developed by Valerio
Pruneri's team. Alfredo Ongaro, ICFO researcher, recalls vividly that "researchers from IrsiCaixa contacted us to see if we could come up with
a solution to the problem of testing and provide a new device that could
detect SARS-COV-2 from saliva, avoiding painful nasal swab sampling,
and achieve accurate results in short time scales, possibly as fast as
an antigen test" A flow virometer The team developed a flow virometer,
a device that uses light to detect the concentration of the virus in
a liquid that flows through a very small tube called a microfluidic
channel. As Rubaiya Hussain, ICFO researcher, explains "the device uses
a couple of drops of saliva and fluorescent light markers.

When saliva is collected from the saliva of a patient's mouth, we
introduce it in a solution that contains fluorescent antibodies. If
the saliva contains any presence of viral particles, the fluorescent
antibodies will attach to the virus." Then, "the reader collects
the sample and sends it into a microfluidic channel that will pass
through a laser illumination detection set-up. The laser illuminates
the sample and if there is presence of viral particles, they will emit
a unique enhancement of the fluorescence signal. In less than 1 minute,
the reading translates into peaks in our graph and alerts the system
that the sample is a positive." The team at ICFO carried out a blind
test with 54 samples provided by IrsiCaixa and were able to confirm
31 cases out of 34 positives with only 3 false negatives. In addition,
they measured 3834 viral copies per milliliter, which is at least three
orders of magnitude lower than that of commercially available rapid
antigen tests, meaning that the device is capable of detecting the
presence of virus at very low concentration levels.

A device used anywhere, by anyone Finally, Ewelina Wajs, ICFO researcher, points out that "Our device is very versatile. By selecting proper
antibodies, this technology could also be adapted for the detection of
other viruses, such as seasonal coronavirus or influenza virus, or even microorganisms in water, such as Legionella and E- coli, with a very
fast response time, with respect to gold standards relying on culture."
The researchers remark that a single device could carry out up to 2000
tests per day. The components that make up the device are low-cost, commercially available off-the-shelf, which allows their large-scale fabrication. In addition, this technique also implies reducing the need
of plastic packaging due to massive testing in one device, which favors
green environment policies.

Finally, due to its low cost and simple operational design, it could
be an excellent solution for diagnosis and spread control in low-income countries where there is limited access to healthcare and vaccines for
all the population. The fact that it does not have to be operated by specialized staff or be in a specialized lab could translate in being
used for mass screening of the population in crowded places such as restaurants, schools, offices, theatres, and cinemas.

========================================================================== Story Source: Materials provided by
ICFO-The_Institute_of_Photonic_Sciences. Note: Content may be edited
for style and length.


========================================================================== Journal Reference:
1. Rubaiya Hussain, Alfredo E. Ongaro, Maria L. Rodriguez de la
Concepcio'n,
Ewelina Wajs, Eva Riveira-Mun~oz, Ester Ballana, Julia` Blanco,
Ruth Toledo, Anna Chamorro, Marta Massanella, Lourdes Mateu, Eulalia
Grau, Bonaventura Clotet, Jorge Carrillo, Valerio Pruneri. Small
form factor flow virometer for SARS-CoV-2. Biomedical Optics
Express, 2022; 13 (3): 1609 DOI: 10.1364/BOE.450212 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/02/220222135429.htm

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