Lateral flow assays allow for the detection of target substances like proteins, hormones, nucleic acids, and antibodies in liquid samples using a simple, portable test strip format. The sample flows laterally along the test strip which contains attached reagents that produce a visible signal if the target is present. This allows for rapid, low-cost, and easy to use testing that can be performed anywhere. Various sample types can be analyzed including whole blood, urine, and food extracts. Lateral flow assays are well established in industries like food/agriculture and medical diagnostics for their ability to quickly screen for the presence of analytes.

1. Lateral Flow Assay
ROMANCE MANNA

2. What is Lateral Flow Assay?
• In a single word lateral flow assays or the immune-chromatographic
assays are the detection method for knowing presence of target
substance in a liquid sample like blood, urine, sputum etc. in a low
cost method and we can do it anywhere.

3. Common names for Lateral Flow
Immunoassay
• Lateral flow test
• Lateral flow device
• Lateral flow assay
• Lateral flow immune assay
• Dipstick
• Express test
• Pen-side test
• Quick test
• Rapid test
• Test strip

4. Types of lateral flow tests
• Sandwich assay- positive tests shows coloured line at the test line.
• Competitive assay- positive tests represented by absence of a colour
line at the test position.
• Multiplex detection assay -Multiplex detection format is used for
detection of more than one target species and assay is performed
over the strip containing test lines equal to number of target species
to be analyzed.

5. Types of sample matrices
• Milk
• Whole blood
• Serum
• Saliva
• Urine
• Tissue sample
• Food
• Drink
• Animal feed
• Plant material
• Water

6. How does lateral flow test work?
• The sample pad acts as the first stage of the absorption
process, and in some cases contains a filter, to ensure the
accurate and controlled flow of the sample.
• The conjugate pad, which stores the conjugated labels and
antibodies, will receive the sample. If the target is present,
the immobilised conjugated antibodies and labels will bind
to the target and continue to migrate along the test.

7. • As the sample moves along the device the binding reagents
situated on the nitrocellulose membrane will bind to the
target at the test line. A coloured line will form and the
density of the line will vary depending on the quantity of the
target present. Some targets may require quantification to
determine target concentration. This is where a rapid test
can be combined with a reader to provide quantitative
results.
• The sample will pass through the nitrocellulose membrane
into the absorbent pad. The absorbent pad will absorb the
excess sample. The specification of the absorbent pad will
have an impact on the volume of sample the test can
incorporate

8. Example and Diagram

10. New generation Lateral flow assay
• Nucleic acid lateral flow assays: PCR amplified products can
be detected.
• Biochips: Multiplex microarray lateral flow format
• Microfluidic chips: Lab on a chip: from sample extraction to
detection without human intervention

11. Summary
• It can be used for detection protein, happens, nucleic acid, amplicons
and as well as antibodies.
• It’s well established in the field of food, agriculture and medical
industries/diagnosis.
• The principle of an LFA is based on the movement of liquid sample on
a polymeric strip with attachment molecule that interact with the
sample molecule and providing a visual signal. Although the concept
is simple but the architecture of the device is complex.
• LFA is a fast, low cost, portable and easy to use assay which gives you
the mostly qualitative results. That result can be verified by farther
quantitative methods.

12. References
• Pedro Estrela, Katarzyna M. Koczula, Andrea Gallotta; Lateral flow
assays. Essays Biochem 30 June 2016; 60 (1): 111–120. doi:
• https://www.abingdonhealth.com/contract-services/what-is-a-
lateral-flow-immunoassay/

13. T H A N K
Y O U