Lateral Flow Tests
NanoRepro AG specializes in the development and commercialization of immunochromatographic lateral flow tests (LFTs) for the diagnostic detection of biomarkers. LFTs are cost-effective and easy-to-use rapid tests that are increasingly used in point-of-care medicine. LFTs are used in growing numbers in home care, in clinical diagnostics and in countries with a low medical infrastructure due to the reliable testing system, the cost-effective materials, the low need for personnel training and the high specificity of the test results.
How the test system works
Lateral flow tests can usually be performed with a single sample application of human origin (for example urine, blood, faeces or sperm) and provide a reliable test result within a short period of time (5-30 minutes). They are based on the use of naturally occurring antibodies in the human body, whose high specificity and precision can be utilized for LFTs. Antibodies are part of the body's own immune system and are used to identify substances foreign to or dangerous for the body and to flag them for degradation or attack by the immune system. In the case of viruses, bacteria and other pathogens, this process is desirable, necessary and intended, but in the case of allergies, the body recognizes in this way actually harmless substances, or depending on the disease even body structures as dangerous and reacts with a defensive reaction.
The antibodies used in the LFTs are mostly monoclonal antibodies. This means that they always recognize and bind exactly one structure (epitope) of a target molecule. On the other hand, there are polyclonal antibodies. This is a mixture of different antibodies which are all directed against different epitopes of an antibody-generating substance (antigen).
For the LFT method it is also of advantage that antibodies can be coupled to various nanoparticles (e.g., gold or latex) and thus produce a colored reaction.
The design of a lateral flow test is based on a carrier card (the backing card). A sample pad, a conjugate pad, a test zone and an absorbent pad are applied to this card. The conjugate pad contains antibodies labeled with a colored substance which specifically bind and recognize the substance (the analyte) to be detected. Two different types of antibodies are usually applied to the test zone. In the region of the T-line, which appearance generally indicates a positive test result, antibodies against the analyte to be detected are applied stationary. These, however, bind to a different epitope than the color-labeled antibody from the conjugate pad. In the region of the C line, whose appearance as an internal reference indicates a correct test procedure, antibodies are plotted which are directed against the antibodies present in the conjugate pad.
If the sample is now applied to the sample pad, it migrates through the backing card by capillary forces. The antibodies which are applied to the conjugate pad react with the analyte present in the sample. When the sample continues to migrate across the backing card, the analyte, which now binds the color-labeled antibodies on the one hand, reacts with the stationary antibodies in the region of the T-line. The formation of an antibody - analyte - antibody structure is called a sandwich complex. Excess antibodies from the conjugate pad which have not bound to an analyte and therefore do not remain on the T-line continue to migrate over the backing card until they reach the region of the C line and are bound there. A colored C-line appears, which indicates a proper test procedure.
Application of lateral flow tests
NanoRepro AG offers lateral flow tests for various applications. In the area of family planning, we can offer the customer tests for determining pregnancy, ovulation, sperm count in male ejaculate and assessment of the occurrence of menopause.
In the area of prevention and allergy detection, NanoRepro AG offers tests for the detection of allergies to grasses, house dust mites, cat hair, gluten, egg or milk (a milk allergy is however not to be confused with a lactose intolerance).
The product portfolio is complemented by the rapid tests for the presence of a Helicobacter pylori infection of the stomach, a vaginal infection by the Candida pathogen, the presence of a possible iron deficiency and the presence of occult blood in the stool. Furthermore, NanoRepro AG offers rapid tests on the concentration of breath alcohol and the presence of metabolic products which indicate the use of drugs (controlled or illegal substances).