Lateral flow test are devices that are paper-based used to detect the presence or absence of an analyte targeted in a liquid matrix such as pathogens, contamination in a water supply system, animal feeds, foodstuffs or even biomarkers in animals or humans. The lateral flow test usually replaces the costly and highly specialized equipment used in the various medical diagnostic tests for point of care testing, home testing or even laboratory use. One of the commonly used lateral flow tests is the home pregnancy test. There are various capillary beds including micro-structured polymer, pieces of porous paper or even sintered polymer that help in transporting fluids simultaneously.
The sandwich assays and the competitive assays are the most common types of the lateral flow test. Both works differently where a positive test in sandwich assays will be known when a coloured line appears at the test line position while in competitive assays, a positive test will be indicated when a positive line does not appear at the test line position. A line that’s appears in the test position in sandwich assays is usually a second line and it usually contains the antibodies that have picked the latex or the gold confirming a correct operation of the test. The sample used in the lateral test flow usually moves through the test tube into the conjugate pad, to the nitrocellulose membrane till it gets to the absorbent pad. To ensure accuracy and efficiency in the results obtained, the labels during development should be made such that they enhance interaction easily with the antigens and antibodies.
The sample pad may have some filters added to ensure that there is accurate and controlled flow of the sample such as urine since it is where the sample is usually absorbed. If the targeted analyte are present in the sample as it moves through the conjugate pad, they will combine with the conjugated labels and antibodies and continue moving along the test device. At the nitrocellulose membrane, the binding reagents will bind at the test line to the target. A coloured line is formed where the density varies depending on the present target analytes. In order to know of the exact quantity of the analytes in the sample, a reader in the lateral flow test can be used. The excess sample is usually absorbed in the absorbent pad.
With a lateral flow reader, it is quite effective in testing the amount of mycotoxin present in food and other agricultural productions so as to prevent contamination in humans and animals. Few minutes are usually used to carry out the various test that makes use of the lateral flow tests. There are no reagents that need to be prepared to carry these tests and also very little amount of sample is needed.