Devices which 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 are referred to as lateral flow test. The tests can be used in various medical diagnostic tests such as for the point of care testing, home testing or even laboratory use which replaces costly and specialized equipment. The home pregnancy test is one of the commonly used lateral flow tests. In the test device, the capillary bed is usually made up of the microstructured polymer, pieces of porous paper or even sintered polymer that help in transporting fluids simultaneously.
There are two types of lateral flow tests which include the sandwich assays and the competitive assays. 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. When a second line appears at the test line in the sandwich assays it usually contains the antibodies that have picked the latex or the gold confirming a correct operation of the test. A sample moves through the test tube into the conjugate pad, to the nitrocellulose membrane till it gets to the absorbent pad in the lateral flow test. Easy interaction of the label in the test device with the antigens and antibodies leading to efficient and accurate results and this can be looked into during the label development.
At the sample pad, the sample will be absorbed and it may be having filters to ensure controlled and accurate flow of the given sample such as urine. At the conjugate pad, the sample is present and if the targeted analyte is present, it combines with the conjugated labels and antibodies as it moves along the test device. At the nitrocellulose membrane, the binding reagents will bind at the test line to the target. A coloured line whose density varies depending on the quantity of the analytes will appear. In order to get the right quantity and concentration of the present targets analytes, a reader can be incorporated on the lateral flow test. The excess sample is usually absorbed in the absorbent pad.
A lateral flow test reader is very effective in determining better ways to screen mycotoxins in food and the agricultural producers to prevent lethal effects likely to happen from contamination. It is quite fast to carry out these test as it just takes a few minutes. The sample needed to carry out the test do not require preparation of different reagents and the sample needed is quite minimal to provide accurate results.