Tag Archives: Wei Liu

Gold nanoparticles make a new promise: a non-invasive COVID-19 breathalyser

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I believe that swab they stick up your nose to test for COVDI-19 is 10 inches long so it seems to me that discomfort or unpleasant are not the words that best describe the testing experience .

Hopefully, no one will have to find inadequate vocabulary for this new COVID-19 testing assuming that future trials are successful and they are able to put the technology into production. From an August 19, 2020 news item on Nanowerk,

Few people who have undergone nasopharyngeal swabs for coronavirus testing would describe it as a pleasant experience. The procedure involves sticking a long swab up the nose to collect a sample from the back of the nose and throat, which is then analyzed for SARS-CoV-2 RNA [ribonucleic acid] by the reverse-transcription polymerase chain reaction (RT-PCR).

Now, researchers reporting in [American Chemical Society] ACS Nano (“Multiplexed Nanomaterial-Based Sensor Array for Detection of COVID-19 in Exhaled Breath”) have developed a prototype device that non-invasively detected COVID-19 in the exhaled breath of infected patients.

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An August 19, 2020 ACS news release (also received via email and on EurekAlert), which originated the news item, provides more technical details,

In addition to being uncomfortable, the current gold standard for COVID-19 testing requires RT-PCR, a time-consuming laboratory procedure. Because of backlogs, obtaining a result can take several days. To reduce transmission and mortality rates, healthcare systems need quick, inexpensive and easy-to-use tests. Hossam Haick, Hu Liu, Yueyin Pan and colleagues wanted to develop a nanomaterial-based sensor that could detect COVID-19 in exhaled breath, similar to a breathalyzer test for alcohol intoxication. Previous studies have shown that viruses and the cells they infect emit volatile organic compounds (VOCs) that can be exhaled in the breath.

The researchers made an array of gold nanoparticles linked to molecules that are sensitive to various VOCs. When VOCs interact with the molecules on a nanoparticle, the electrical resistance changes. The researchers trained the sensor to detect COVID-19 by using machine learning to compare the pattern of electrical resistance signals obtained from the breath of 49 confirmed COVID-19 patients with those from 58 healthy controls and 33 non-COVID lung infection patients in Wuhan, China. Each study participant blew into the device for 2-3 seconds from a distance of 1¬-2 cm. Once machine learning identified a potential COVID-19 signature, the team tested the accuracy of the device on a subset of participants. In the test set, the device showed 76% accuracy in distinguishing COVID-19 cases from controls and 95% accuracy in discriminating COVID-19 cases from lung infections. The sensor could also distinguish, with 88% accuracy, between sick and recovered COVID-19 patients. Although the test needs to be validated in more patients, it could be useful for screening large populations to determine which individuals need further testing, the researchers say.

The authors acknowledge funding from the Technion-Israel Institute of Technology.

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Here’s a link to and a citation for the paper,

Multiplexed Nanomaterial-Based Sensor Array for Detection of COVID-19 in Exhaled Breath by Benjie Shan, Yoav Y Broza, Wenjuan Li, Yong Wang, Sihan Wu, Zhengzheng Liu, Jiong Wang, Shuyu Gui, Lin Wang, Zhihong Zhang, Wei Liu, Shoubing Zhou, Wei Jin, Qianyu Zhang, Dandan Hu, Lin Lin, Qiujun Zhang, Wenyu Li, Jinquan Wang, Hu Liu, Yueyin Pan, and Hossam Haick. ACS Nano 2020, XXXX, XXX, XXX-XXX DOI: https://doi.org/10.1021/acsnano.0c05657 Publication Date:August 18, 2020 Copyright © 2020 American Chemical Society

This paper is behind a paywall.

An easier, cheaper way to diagnose Ebola

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A Sept. 9, 2015 news item on Nanotechnology Now highlights a new technology for diagnosing the Ebola virus,

A new Ebola test that uses magnetic nanoparticles could help curb the spread of the disease in western Africa. Research published in Biosensors and Bioelectronics shows that the new test is 100 times more sensitive than the current test, and easier to use. Because of this, the new test makes it easier and cheaper to diagnose cases, enabling healthcare workers to isolate patients and prevent the spread of Ebola.

The authors of the study, from the Chinese Academy of Sciences, say their new technology could be applied to the detection of any biological molecules, making it useful to diagnose other infectious diseases, like flu, and potentially detect tumors and even contamination in wastewater.

A Sept. 9, 2015 Elsevier press release, which originated the news item, provides more detail,

The Ebola virus causes an acute illness that is deadly in half of all cases, on average. The current outbreak of Ebola, which started in March 2014, affects countries in west Africa. In the most severely affected countries, like Guinea, Liberia and Sierra Leone, resources are limited, making control of the outbreak challenging. There is no vaccine for Ebola, so detecting the virus is key to controlling the outbreak: with an accurate diagnosis, patients can be isolated and treated properly, reducing the risk of spread.

“In west Africa, resources are under pressure, so complicated, expensive tests are not very helpful,” said Professor Xiyun Yan, one of the authors of the study from the Chinese Academy of Sciences. “Our new strip test is a simple, one-step test that is cheap and easy to use, and provides a visible signal, which means people don’t need training to use it. We think it will be especially helpful in rural areas, where technical equipment and skills are not available.”

Currently there are two ways to test for the Ebola virus: using a method called polymerase chain reaction (PCR), which makes copies of the molecules for detection, and with antibody-capture enzyme-linked immunosorbent assay (ELISA), which gives a visual indication when a given molecule is in a sample. PCR is very sensitive, but is expensive and complicated, requiring special skills and technical equipment. The ELISA – or gold strip test – is cheaper but sensitivity is very low, which means it often gives the wrong results.

The new test, called the nanozyme test, uses magnetic nanoparticles, which work like enzymes to make the signal stronger, giving a clearer result you can see with the naked eye. The test can detect much smaller amounts of the virus, and is 100 times more sensitive than the gold strip test.

“People have loved the strip test for many years, but it has a major weakness: it’s not sensitive enough. We’re very excited about our new nanozyme test, as it is much more sensitive and you don’t need any specialist equipment to get a quick, accurate result,” said Dr. Yan.

Strip tests work by attaching molecules called antibodies to gold particles to look for a particular molecule in a sample. When they attach to the molecule you’re looking for, in this case a virus, they produce a signal, such as a color change. In order to find the virus, the particles need to be labelled with enzymes, which speed up detection and signalling.

With the new nanozyme test, the researchers applied magnetic nanoparticles as a nanozyme probe in place of gold nanoparticles. After labeling with an antibody that attaches to the Ebola virus, this novel probe is able to recognize and separate the virus in a sample. The nanoparticles are magnetic, so to concentrate the virus particles in a sample, all you need to do is hold the sample against a magnet; no expensive equipment is needed.

The nanozyme test is 100 times more sensitive than the gold strip test, detecting molecules called glycoproteins on the surface of the Ebola virus at concentrations as low as 1 nanogram per milliliter.

The researchers have applied for a patent for the new test, which is currently being taken to west Africa by the CDC to use in the field. The researchers are also collaborating with clinical teams to apply the technology to other diseases, and with a company that treats wastewater to see if it can help remove environmental contamination.

Here’s a link to and a citation for the paper,

Nanozyme-strip for rapid local diagnosis of Ebola by Demin Duan, Kelong Fan, Dexi Zhang, Shuguang Tan, Mifang Liang, Yang Liu, Jianlin Zhang, Panhe Zhang, Wei Liu, Xiangguo Qiu, Gary P. Kobinger, George Fu Gao, Xiyun Yan. Biosensors and Bioelectronics Volume 74, 15 December 2015, Pages 134–141 doi:10.1016/j.bios.2015.05.025

This paper appears to be open access.