by Lateral flow assays, also known as lateral flow immunochromatographic assays, are a common diagnostic testing method used to detect the presence or absence of targeted substances in biological samples like blood or urine. This testing method relies on selective biological interactions between the target substance, such as a protein, and its matching reagents or antibodies. The presence of target substances in a sample causes these interactive reactions to occur and produce a clearly visible signal on the assay strip, indicating a positive result.
Workings
Lateral Flow Assay utilize a porous membrane, usually made of nitrocellulose, as the solid support for the assay. This membrane is embedded with several interactive components through which the liquid sample flows across laterally via capillary action. The key components contained in a typical lateral flow assay include:
– Sample pad: This pad is located at one end of the strip and acts as a reservoir for adding the liquid sample. It helps distribute the sample uniformly onto the membrane.
– Conjugate pad: Located after the sample pad, this pad contains an antigen or antibody that is conjugated to detection particles like colloidal gold, colored latex beads or carbon. This conjugate acts as a detectable label.
– Membrane: The porous membrane, located between the conjugate and absorbent pads, contains a test line and control line. The test line contains a highly specific capturing antigen/antibody for the target analyte. The control line contains an antibody that reacts with the labeled conjugate particles.
– Absorbent pad: Situated at the end of the membrane, this pad absorbs and halts the liquid sample flow, completing the assay.
When the liquid sample is added to the sample pad, it moves across the conjugate pad where pre-coated antibodies conjugated to detectable labels bind to any target antigens present in the sample. The labeled conjugate-antigen complex then flows laterally across the membrane where they are captured by immobilized matching antibodies present on the test line. This leads to the formation of a colored test line, indicating a positive result. Excess labeled conjugates continue flowing and get captured by antibodies on the control line, forming a second colored line. This ensures procedural validity even if no target antigen is present.
Key Advantages of Lateral Flow Assays
– Simple design and easy-to-use format: LFAs do not require any specialized equipment or technical training for performing the test and reading results. The entire assay can be completed within 10-30 minutes.
– High sensitivity and specificity: Modern LFAs can achieve detection limits on par with standard laboratory tests using advanced conjugate labels, capturing antibodies and membrane materials.
– Rapid results: Being a simple benchtop assay, LFAs provide results in minutes compared to standard laboratory tests requiring hours or days.
– Low cost: These assays have a very low material and production cost, making them affordable for point-of-care and home-based testing.
– Stable shelf life: If designed and stored properly, LFAs demonstrate long stability of 6-24 months without requiring refrigeration.
– Diverse applications: Due to their versatility, lateral flow assays are used for detecting various analytes like proteins, antibodies, hormones, drugs, toxins, and infectious pathogens.
Applications of Lateral Flow Assay Technology
Pregnancy Testing
Lateral flow immunoassays are the most widely used technology for detecting human chorionic gonadotropin (hCG) for pregnancy testing using urine samples. These over-the-counter tests provide reliable results within 3-5 minutes. The presence of hCG in a pregnant woman’s urine results in the formation of a distinct test line on the assay strip.
Infectious Disease Testing
Rapid infectious disease diagnosis using LFAs helps initiate early treatment and control the spread of epidemics/pandemics. Popular applications include testing for HIV, respiratory viruses, malaria, tuberculosis, and more recently SARS-CoV-2. These tests are deployable at POC facilities, homes or field conditions in resource-limited settings.
Cardiac Marker Testing
Cardiac biomarker levels are measured using LFAs to aid in the rapid diagnosis of acute myocardial infarction and other heart conditions. Common analytes detected are myoglobin, troponin I and T during the early stages of cardiac injury.
Drugs of Abuse Testing
Lateral assays provide a convenient method for testing urine or oral fluid samples to detect the presence of illicit/recreational drugs. Workplaces, law enforcement agencies and drug rehabilitation centers employ drug testing assays to monitor drug use.
Future Advancements
Advancements in nanotechnology, bioconjugation methods and materials science are enabling the development of more sensitive, multiplexed and automated lateral assays. Research efforts are focused on integrating lateral flow strips with smartphone readers for quantitative, real-time analysis. This would increase adoption of LFAs not just for screening but also for confirmatory diagnosis and disease monitoring applications. Connecting test results to centralized diagnostic networks can boost telehealth opportunities globally. Overall, rapid progress in LFA technology promises wider diagnostic access and affordable healthcare for all.
*Note:
1. Source: Coherent Market Insights, Public Source, Desk Research
2. We have leveraged AI tools to mine information and compile it.
About Author - Ravina Pandya
Ravina Pandya,a content writer, has a strong foothold in the market research industry. She specializes in writing well-researched articles from different industries, including food and beverages, information and technology, healthcare, chemicals and materials, etc. With an MBA in E-commerce, she has expertise in SEO-optimized content that resonates with industry professionals. LinkedIn Profile
