Colloidal Gold Immunochromatography is one of the most popular rapid tests that are based on gold nanoparticles as the immunochromatographic markers. This method is also referred to as the lateral flow immunoassay (LFIA) and is applied in point-of-care diagnosis. It gives a visible indication in the form of red or pink lines and does not require complex instruments for interpretation as is the case with most modern laboratory technologies such as colloidal gold.
In this article, the working principle of colloidal gold immunochromatography, its components, application, advantages, and some shortcomings and development tendencies will be introduced.
Colloidal gold immunochromatography also known as lateral flow assay is based on the reaction between antigens and antibodies in the sample which may be blood, urine, or saliva. The sample is applied on a test strip which is composed of several zones for sample application, reagent reaction, and result indication. The strip is typically composed of nitrocellulose, and the colloidal gold is labeled with antibodies to prepare the detection reagent.
If the target antigen is present in the sample, it reacts with the colloidal gold-labeled antibodies, and a complex forms. As the sample moves along the strip, this complex goes to particular regions where other antibodies are anchored. These antibodies bind to the antigen-colloidal gold complex and form a visible colored line on the test strip. This line shows the presence of the target antigen and in some cases gives qualitative or semi-quantitative results.
Some of the main elements of Colloidal Gold Immunochromatography include;
Colloidal gold is used in these assays because of its great optical characteristics which are easily observable even without the help of a microscope. Gold nanoparticles are generally spherical and their size varies between 5 and 50 nanometers. When conjugated with antibodies, they maintain stability and produce a red or pink coloration, thus making the detection process easy and fast.
The antibodies conjugated to colloidal gold nanoparticles enable these particles to serve as a carrier and a signal marker at the same time. When the sample that is being investigated is placed on the strip, any of the antigens present in the sample attach themselves to the antibodies which are linked to gold particles. During the migration of the sample along the strip, the antigen-antibody complex is captured at the test line by the antibodies that are bound to the strip and are specific to the antigen. More colloidal gold particles, which are not combined with the antigen, move along the strip to the control line to testify to the accuracy of the test.
Colloidal gold immunochromatography is an effective technique applied in different areas of knowledge. Below are some of its common applications: Below are some of its common applications:
Colloidal gold immunochromatography is used in most medical diagnostic tests and is particularly popular in rapid point-of-care testing. Some notable examples include:
Colloidal gold immunochromatography is also used in veterinary diagnostics for the diagnosis of disease in animals. These tests are essential in controlling disease in livestock and other animals, tracking zoonotic diseases, and quality of animal-derived products.
H2: Colloidal Gold Immunochromatography: The Perks of Its Utilization
Colloidal gold immunochromatography offers several advantages, making it a preferred diagnostic method in many applications: Colloidal gold immunochromatography has several advantages which make it a method of choice in many applications:
The other benefit of colloidal gold-based assays is the time that is taken to perform the assays. They usually take a few minutes to prepare and are therefore useful in situations where decisions are needed at the time of examination. Furthermore, the tests are easy to perform and the results can be understood without going through professional training.
One advantage of the tests is that the tests are not very elaborate and they can be easily transferred from one place to the other. This is so especially in the present world where resources are scarce as well as where there are no laboratory facilities to conduct tests.
This makes colloidal gold stable and therefore these tests have long shelf lives and are ideal for large-scale storage and distribution. They can be kept at normal temperatures and they are not in any way related to the climate change conditions.
Despite its numerous benefits, colloidal gold immunochromatography does have some limitations that need to be considered:
Even though the colloidal gold-based assays have high sensitivity for qualitative detection, they are less sensitive in comparison with the ELISA or PCR techniques. At times this detection limit may be relatively high such that it fails to detect analytes as is needed in some applications such as trace analysis.
Colloidal gold immunochromatography sometimes gives out a false positive or a false negative and has at times been misleading. This can be due to interference with the substances in the sample or even wrong handling of the test strip. Sometimes, it is necessary to repeat the tests with better accuracy and sensitivity of the laboratory techniques.
These tests yield results that are either qualitative or semi-quantitative, therefore they notify of the existence or otherwise of the target analyte but not its quantity. If there is a need to provide an accurate measurement, then other techniques have to be employed.
Colloidal gold immunochromatography is an effective and multi-functional method of diagnosis, which is appreciated for its usage, duration, and cost. Commonly applied in clinical diagnosis, food analysis, and ecological testing, this approach offers rapid, straightforward readouts at the point of need. However, it has some drawbacks and still, there is a constant development in nanotechnology and assay, which enhances its sensitivity and the number of uses. With the development of these technologies, colloidal gold immunochromatography will remain an important part of contemporary diagnostics, especially in cases when rapid on-site analysis is needed.
Colloidal gold immunochromatography operates based on gold nanoparticles that are conjugated to antibodies to identify the existence of particular antigens. When a sample is applied on the test strip, the colloidal gold which is conjugated to the target antigen migrates to the test line and forms a red or pink line.
Colloidal gold immunochromatography is applied in various fields such as medical diagnostics including pregnancy and infectious diseases, food safety for detecting bacterial pathogens such as Salmonellae, and in environmental monitoring including testing water for contaminants.
It is preferred and recommended to use colloidal gold because it has a distinguishable color that enhances the outcome to be read. It is highly stable and economical and can be used in all sorts of assays making it a very effective method to detect many kinds of analytes.
ANTITECK provide uncut sheet rapid test for immunochromatographic test manufacturing, contact us for more information via [email protected]
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