What is a lateral flow test – Here is all you need to know.

It is explained in detail in the following article what a lateral flow test is and how it may be used. Additionally, the article discusses how lateral flow tests are performed and the many parts used throughout the manufacturing process.

Lateral flow test common names

Lateral flowflex covid test has become associated with the COVID-19 standardization process (SARS-CoV-2). On the other hand, lateral flow technology has been around far longer than COVID. As a result, various industrial sectors and nations use different languages to define what lateral flow tests are and how they work. The following are examples of familiar names:

• (LFT) Lateral flow test 
• (LFD) Lateral flow device
• (LFA) Lateral flow assay 
• (LFIA) Lateral flow immunoassay 
• Rapid test
• Immunochromatographic assays Lateral flow 
• Test strip
• Dipstick
• Pen-side test
• Quick test
• Express test

An immunoassay that uses lateral flow is called what?

In other words, what does the term “lateral flow immunoassay” mean? With this equipment, many other types of analytes, such as pathogens, biomarkers, and pollutants in water, food, and animal feed, may be tested for. The pregnancy test is the most well-known form of lateral flow fast test strip.

In addition to one or more target or test lines, LFAs often include a control line to verify that the test is functioning correctly. They are meant to be simple and need little or no training. If paired with reader technology, including AppDx®, they may offer quantitative data.

Many industries use lateral flow tests for point-of-care testing. Professionals, skilled lay users, or patients may all utilize them, and they can be used in a variety of locations, including the laboratory, clinic, or at home. There are stringent regulations in the medical diagnostic sector that all goods must follow.

Aside from the pharmaceutical business, lateral flow quick tests are also employed in the environmental testing and animal health industries and the food and feed industry.

How does a lateral flow test work?

Results from LFDs are commonly obtained by the use of the immunoassay technique based on nitrocellulose membrane, antibodies, and colored nanoparticles (or labels).

Flowing through a conjugate pad into a nitrocellulose membrane, the sample is transferred to the absorbent pad when a sample is inserted. A sandwich assay’s steps are outlined in the following bullet points. 

• This pad is the initial step in the absorbance process and may incorporate a filter to guarantee that the sample flows accurately and precisely.

• The sample will be sent to the conjugation pad, which has the conjugated labels & antibodies. As long as the target is there, the antibodies and labels that have been immobilized will continue to travel along with the test.

• Binding reagents located on the nitrocellulose membrane would bind to the target at the test line as the sample passes along the device in transit. A colored line will appear, and the density of a line will change based on the amount of the target. Quantification may be necessary for specific targets to establish their concentration. The combination of a reader with a fast test may provide quantifiable findings.

• The sample will be absorbed into the absorbent pad after passing through the nitrocellulose membrane. The absorbent pads will absorb the different samples. The amount of samples that may be tested depends on the absorbent pad’s specification.

Types of the Lateral flow test 

Lateral flow assays are available in both dipstick and cassette formats. Dipsticks & housed tests both perform the same functions; the best format for a given industry, sample matrices, and market demands will be determined by these factors.

Sandwich assays:

Such a colored line just at the test line indicates a positive test.

Competitive assays:

A colored line just at the test location is not present in a positive test.

Sample Matrices

The sample utilized in the test will be determined by the target analyte & the market needs. Animal feed, for example, necessitates the use of a running buffer to facilitate sample delivery. Dilution buffers may be used to dilute blood and other bodily fluids that may be used straight to a test without further preparations.

Whole blood and a buffer are used in the AbC-19TM COVID-19 fast antibody test, identifying IgG neutralizing antibodies directed against the SARS-CoV-2 spike protein. Plant disease tests, such as those offered by Pocket Diagnostic, require that the user mix plant material samples with a running buffer to identify economically harmful plant diseases.

Label Types

Carbon, conjugated gold, or colored latex nanoparticles are commonly used in lateral flow assays. Beads made of magnets or colored polystyrene can also be used as labels. It doesn’t matter what kind of label you use; all of them perform the same function: to create a three-way bond between antibodies, targets, and control and test lines.

Several factors, such as the target, matrix, sample, and antibody, will influence the label selection during lateral flow development. Antibody and antigen labels must interact correctly for results to be accurate and efficient. Transfer & scale-up into routine manufacturing can’t happen without this. It’s crucial.

Lateral Multiplexed Flow Assays

One or more test lines may be included in sandwich and competitive assays. For example, in our PCRD nucleic acid lateral flow immunoassay, we have two test lines and one control line. Sandwich & competitive multiplexed assays, which use complementary reader technology, can also yield quantitative results.

Possible applications for a multiplexed assay

The following are possible applications for a multiplexed assay:

• Instead of doing several separate tests, a single test might identify multiple targets. A multiplex assay is an excellent tool to have to make the most of a limited sample amount.
• To aid in the detection of diseases if many indicators are present;
• High-volume food & feed testing to confirm the presence of numerous pollutants;
• End-users may save money in the lab or on the job site by running many tests simultaneously.
• There are instances where resources are limited, and multiplexed testing may save time.