Choose the right lateral flow approach for your workflow

Lateral flow assays are used across two main workflows: developing custom assays and using ready-to-run tests. Understanding which approach you need can help you select
the right reagents and streamline your workflow.

For assay developers

• Build and optimize custom lateral flow assays
• Conjugate antibodies to detection labels
• Select membranes, pads, and assay components

For end users

• Use ready-to-run lateral flow assays for rapid detection
• Focus on ease of use, speed, and reproducibility
• Typically applied in point-of-care testing, screening, or routine analysis

Explore our range of lateral flow solutions to support both assay development and rapid testing workflows.

Overview of lateral flow assays

Lateral flow assays have traditionally relied on the use of antibodies that have been conjugated to colored detection moieties such as gold nanoparticles or latex beads. Colorimetric readouts allow rapid visual assessment of the assay result, however, despite the extensive and well-documented use of colorimetric detection methods, many researchers are instead turning to fluorescent labels such as fluorescent dyes, fluorescent proteins or Europium particles, since these offer several advantages:

• Greater assay sensitivity
• Quantitative readout
• Possibility of multiplexing

Colloidal gold lateral flow assays

Colloidal gold nanoparticles are the most widely used detection method in lateral flow assays, enabling simple, rapid, and equipment-free visual readouts.

Gold-based assays produce a visible colored line at the test region, making them ideal for point-of-care and field-based applications.

Key advantages

• No instrumentation required
• Rapid visual results
• Cost-effective and scalable
• Well-established and widely validated

Typical applications

• Infectious disease testing
• Pregnancy and hormone detection
• Food safety screening
• Environmental monitoring

Gold nanoparticles and conjugation kits are commonly used during assay development to generate stable antibody-label conjugates for colorimetric detection.

Explore our gold nanoparticles

Explore our gold conjunction kits

Point-of-care and rapid testing applications

Lateral flow assays play a key role in point-of-care (POC) and rapid testing environments due to their speed and simplicity.

These assays are designed to deliver results in minutes, making them suitable for both laboratory and non-laboratory settings.

Common application areas

• Infectious disease detection
• Food safety testing
• Environmental monitoring
• Veterinary diagnostics

Their ease of use and minimal equipment requirements make them particularly valuable for decentralized testing.

Fluorescent and advanced detection methods

Expedeon offers a wide range of products to support this, including kits for producing fluorescently labeled reagents.

Lightning-Link^® for the production of fluorescently-labeled antibodies

Our Lightning-Link® technology enables the direct labeling of antibodies, proteins, peptides, or any other biomolecule with free amine groups. The product range includes kits for labeling biomolecules with a wide range of fluorophores, covering the spectrum from UV to far infra-red, and is therefore ideally suited to the production of reagents for use in lateral flow assays which require an immunofluorescent readout.

The Lightning-Link^® kits are extremely quick and easy to use. The conjugation reaction is initiated simply by adding the biomolecule to a vial of the lyophilized mixture which contains the label of interest and incubating.

• No separation steps
• 100% material recovery
• Stable covalent conjugates

Although it is possible to visualize many fluorescently-labeled antibody conjugates by eye (provided the antibody conjugate is present at a suitable concentration), it is more common to use a specialized strip reader for fluorometric detection. This should be fitted with the relevant filters for detection of the fluorophore and, if a multiplexed lateral flow assay is performed, the properties of each fluorophore should be carefully considered.

Lateral flow strip reader compatibility

Fluorescent and Europium-based lateral flow assays typically require a compatible strip reader for detection and quantification.

Key considerations:

• Excitation and emission compatibility with fluorophore
• Detection sensitivity and dynamic range
• Multiplex detection capability

Specialized lateral flow strip readers or fluorescence readers equipped with appropriate filters are commonly used.

Euporium conjugation kits

For lateral flow assays that require an even higher degree of sensitivity, we offer our Europium Conjugation kit (ab269889). These allow direct labeling of antibodies, proteins, peptides, or any other biomolecule with free amine groups to 200 nm Europium (Eu) chelate microspheres. Our Europium particles have a specially treated surface, allowing the generation of highly stable, covalent conjugates which are resistant to aggregation and require no extensive pH optimization

Labeling with Europium particles provides up to 15-fold higher sensitivity compared with other particle-based assays, in part due to Europium’s large Stokes shift.

• Max absorbance: 365 mm
• Max emission: 610 mm
• Long fluorescence lifetime (µseconds)

These properties enable time-resolved fluorescence and reduced background signal.

Sensitivity comparison of detection methods

Different detection strategies offer varying levels of sensitivity and performance.

Lateral flow assay components and membrane selection

Understanding the role of each component is essential for effective lateral flow assay design.

Key components

• Sample pad – prepares and distributes sample
• Conjugate pad – stores labeled antibodies
• Nitrocellulose membrane – contains test and control lines
• Absorbent pad – drives capillary flow

Membrane selection factors

• Flow rate
• Binding capacity
• Signal-to-noise ratio

Optimizing these components is critical for assay sensitivity and reproducibility.

Conjugation check kits to confirm successful antibody conjugation

Our conjugation check kits can be used to confirm the successful conjugation of an IgG antibody to a colored label. It is compatible with antibody conjugates produced using:

• Lightning-Link ® kits
• Colloidal gold
• Latex conjugation kits

^{Conjugate Check&Go! evaluation of antibody conjugates generated using Lightning-Link®. Conjugate Check&Go! was used to confirm successful conjugation of an IgG to a fluorescent protein (RPE), tandem dye (APC/Cy5.5), or fluorescent dye labels (Fluorescein, Cy5.5). The line intensity varies according to the choice of label, with fluorescent dyes requiring a higher concentration of the antibody conjugate to produce a visible line compared to fluorescent proteins and tandem dyes. The intensity of the line is also dependent on the color of the label.}

Dipstick lateral flow assay

During a dipstick assay, the conjugated antibody is added directly to a solution containing the target analyte. The lateral flow test strip is then dipped into the solution.

The analyte becomes bound at a test line, while the control line confirms assay validity.

^{Dipstick lateral flow assay for evaluation of an antibody-Europium particle conjugate. The schematic represents the assay format: an anti-CRP antibody was conjugated to Europium particles using Innova’s Europium Conjugation Kit, and the conjugate was added to a solution containing a known concentration of CRP. A dipstick lateral flow test strip, consisting of a nitrocellulose membrane and a wicking pad, was dipped in to the solution. A positive result at the Test line indicates the presence of CRP. The image of the lateral flow strips shows data obtained from the UV transilluminator, demonstrating low background, no signs of aggregation, and a sensitivity of 0.25–0.5 ng/mL. The graph shows the same data obtained from the lateral flow strip reader, with a sensitivity of 0.063 ng/mL. Please note that a Control line was not included in this instance.}

Strip test lateral flow assay

The main difference between a dipstick assay and a strip test assay is that a strip test includes a conjugate release pad, where the conjugated antibody has been dried.

The sample flows through the strip, interacting with reagents before binding at the test and control lines.

Applications and use cases

Lateral flow assays are commonly used across research and applied testing environments, including:

• Rapid diagnostics and screening
• Biomarker detection
• Food safety testing
• Environmental monitoring
• Assay development and optimization

^{Strip test lateral flow assay for evaluation of an antibody-Europium particle conjugate. The schematic represents the assay format: an anti-CRP antibody was conjugated to Europium particles using Expedeon’s Europium Conjugation Kit, and dried in to the conjugate release pad. A solution containing a known concentration of CRP, spiked in to CRP-depleted 100% serum, was then added to the sample application pad. A positive result at the Test line indicates the presence of CRP in the serum. The graph shows data obtained from the lateral flow strip reader, demonstrating low background and high sensitivity. Please note that a Control line was not included in this instance.}