Open Access

Lateral flow assay: a promising rapid point-of-care testing tool for infections and non-communicable diseases

Kumaravel Vealan
Kumaravel Vealan
, 
Narcisse Joseph
Narcisse Joseph
, 
Sharizah Alimat
Sharizah Alimat
, 
Anandi S. Karumbati
Anandi S. Karumbati
 and 
Karuppiah Thilakavathy
Karuppiah Thilakavathy
   | Dec 28, 2023
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Article Category: Review
Published Online: Dec 28, 2023
Page range: 250 - 266
DOI: https://doi.org/10.2478/abm-2023-0068
Keywords
© 2023 Kumaravel Vealan et al., published by Sciendo
This work is licensed under the Creative Commons Attribution 4.0 International License.

Figure 1.

Types of diagnostic methods.
Types of diagnostic methods.

Figure 2.

Components of lateral flow assays.
Components of lateral flow assays.

Figure 3.

Lateral flow assay designs. (A) Sandwich assay or not competitive assay: A visible signal produced at both the test line and control line indicates the positive result. The analyte is present in the sample and hybridized to the capturing molecule at the test line. The absence of analyte gave a negative result where the signal was only produced at the control line. The signal at the control line is a result of the hybridization of the capturing molecule at the control line region that is complementary to the free conjugate molecules. (B) Competitive assay: A visible signal only at the control line gave a positive result, indicating the competition of analytes with the capturing molecule and no aggregation of conjugated particles at the test line. However, the signal at both the test line and control line gave a negative result, indicating the absence of analytes in the sample and binding of conjugated particles to the capturing molecules at the test line.
Lateral flow assay designs. (A) Sandwich assay or not competitive assay: A visible signal produced at both the test line and control line indicates the positive result. The analyte is present in the sample and hybridized to the capturing molecule at the test line. The absence of analyte gave a negative result where the signal was only produced at the control line. The signal at the control line is a result of the hybridization of the capturing molecule at the control line region that is complementary to the free conjugate molecules. (B) Competitive assay: A visible signal only at the control line gave a positive result, indicating the competition of analytes with the capturing molecule and no aggregation of conjugated particles at the test line. However, the signal at both the test line and control line gave a negative result, indicating the absence of analytes in the sample and binding of conjugated particles to the capturing molecules at the test line.

Sensing modality, features, advantages, and disadvantages of various LFAs

Sensing modality Features Advantages Disadvantages References
Optical Colorimetric Colorimetric changes help to make a visual observation for result interpretation Sensitivity issues that lead to result inaccuracy [53]
Fluorescence Provides results with higher signal to noise ratio; higher sensitivity Fluorescent labels are not visible at low concentration; requires external reader for specific analysis [54]
SERS High sensitivity with very low detection limit; can be developed into ultiplex LFA for a wide range of detection Expensive [55]
Chemiluminescence High sensitivity when used together with metal nanoparticles; lower LOD; highly stable for immobilization Requires addition of enzymatic substrate; low shelf-life [56]
Thermal Thermal imaging Improved LOD and high sensitivity; no photo bleaching or photo instability The infrared image sensors are massive; expensive [57]
Laser speckle imaging Uses improved depth resolution reader that improves sensitivity Expensive and not suitable at resource-limited settings [58]
PA imaging PA imaging helps sample penetration deeper that improves the sensitivity of detection Strips need to be dried before analysis since acoustic waves travelling through water-interface is a challenge [44, 59]
Magnetic MPQ Low detection limit and highly sensitive Not suitable for multiplex detection when using high affinity variants [52, 60]
Electrochemical Amperometry, cyclic voltametric, impedimetric The ratio of applied voltage can be adjusted to increase the sensitivity of the detection; nanoparticle integration to improve LOD Requires expensive reagents and multistep procedure [44, 61]

Different properties of various POCT devices

Types Properties References
Qualitative strip–based handheld POCT devices

Immunochromatographic reaction

Signaling depends on the simple visualization of olorimetric changes.

Portable

Test usually done at the site of patients’ care.

E.g.: LFDs, ICSs, and multiplex LFDs

 [17, 18]
Quantitative strip or chip–based with unit use analyzers

Used for quantitative analysis

A reader is used to measure the reaction onto the strip.

Allows to measure the INR levels of certain metabolites or proteins in our body.

Test strips are for single use and disposed after the data collection.

Common for blood sugar and thrombin analysis
Bench top POCT analyzers

Requires sample containers, labelling and needed to be carried out in clinical settings.

Can be set up at different POC locations.

Miniaturized and increased computer processing.

Used for spectrophotometric enzyme-substrate measurement, hemagglutination, immunoassay, and blood gas analysis.

E.g.: agglutination assays, immunofiltration assays
Molecular biology–based/nucleic acid POCT devices

Used for detection of pathogenic diseases.

Rapidly quantifies nucleic acid from numerous infectious agents.

Incorporated molecular biology techniques such as isothermal amplification reaction
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