FRONT PAGES: Building A Better Dipstick Test

dWeb.News Article from Daniel Webster dWeb.News

dWeb.News Article from Daniel Webster dWeb.News

Newswise — LFAs (or lateral flow assays) have been an established point-of-care platform for decades and continue to grow in popularity, particularly in developing countries. These disposable, paper-based diagnostic devices are affordable, widely available, have a long shelf life, and they’re fast, typically delivering test results in less than 20 minutes. They are also very easy to use at home. A few drops of a sample, such as saliva, blood, urine, are added to one end of the dipstick. The results can be read at the opposite end within minutes.

This technology is widely used to detect biomarkers in people and contaminants in food or water. LFA technology is most commonly used to perform at-home pregnancy testing. And more recently, LFA technology has been used successfully in at-home tests for Covid-19.

” These tests have been very popular for many years due to their simplicity. These tests do not require you to send anything to the clinic or lab. This is an advantage,” stated Fatih Saiglu ,, an engineering researcher at the Georgia Institute of Technology. There is also a drawback. There are limitations to what they can do.”

Recognizing the widespread popularity and practicality of dipsticks, particularly in resource-limited settings, Sarioglu and his research team are overcoming those limitations with development of a flow control technology, turning these simple tests into complex biomedical assays.

They explain their research, and its emphasis on flow technology, in two recently published papers in the journals Science Advances and ACS Sensors. The one explains how they developed their technology, while the other uses the technology to diagnose both the coronavirus and influenza.

Controlling the Flow

LFAs utilize capillary liquid flow to detect analytes – capillary flow is the process of liquid passing through a narrow passageway (like a capillary); analytes are substances or chemicals of interest, such as an antibodies or proteins, in an analytical procedure (like an LFA).

Sarioglu stated that traditional LFAs are too cumbersome to perform multi-step assays. Instead, capillary flow makes it impossible for them to coordinate a complex process that involves multiple reagents being applied in a particular sequence and with specific delays.

The team has published studies that describe a method to control capillary flow. This involves imprinting roadblocks onto a laminated sheet of paper coated with water-insoluble ink. This allows the liquid to be blocked from flowing into a void at the interface between the laminated paper with ink and the polymer tape. Researchers can modify the roadblocks to control the formation of voids. This allows them to create timers that maintain capillary flow for the desired time.

“By strategically imprinting these timers, we can program the assays to coordinate different capillary flows,” said Sarioglu, professor in the School of Electrical and Computer Engineering. This allows multiple liquids to enter, as well as multi-step chemical reactions to take place, at optimal incubation times. We can thus perform complex, automated tests that would otherwise have to be done in labs. This takes us beyond the conventional LFA.”

Disposable Lab

For the user, the new dipstick test works the same way as the reliable standard – a sample is added at one end and the results present themselves minutes later in living color(s) at the other end. Sarioglu and his coworkers simply improved and extended the process.

They created immunoassays to detect pathogenic targets such as Zika virus, HIV, hepatitis B, and malaria.

The ACS sensors paper describes a PCR-based, point-of-care kit based on the laboratory’s flow technology. The assay runs a series of chemical reactions to detect SARS-2 (severe respiratory syndrome coronavirus 2), influenza A and B. An expensive and labor-intensive genetic test can now be performed on a disposable platform. This will allow for frequent self-testing which will help to fill a critical need to track outbreaks and control them.

The lab is currently studying the potential application of the technology to other assays that target other pathogens. Plans are to publish the results in the next months. Sarioglu is optimistic that the work will have implications in the current healthcare challenge with Covid-19, and beyond.

” We believe that this flow technology research has a wide impact.” he stated. “This kind of dipstick test is so commonly used by the public for biomedical testing, and now it can be translated into other applications that we do not traditionally consider to be cut out for these simple tests.”

The Georgia Institute of Technology, or Georgia Tech, is a top 10 public research university developing leaders who advance technology and improve the human condition. The Institute offers degrees in business, computing and engineering as well as liberal arts and sciences. Its nearly 40,000 students representing 50 states and 149 countries, study at the main campus in Atlanta, at campuses in France and China, and through distance and online learning. Georgia Tech, a world-class technological university, is a major engine for economic development in Georgia, the Southeast and the Nation. It conducts more than $1 billion annually in research for government, industry and society.

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