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

Vealan, Kumaravel; Joseph, Narcisse; Alimat, Sharizah; Karumbati, Anandi S.; Thilakavathy, Karuppiah

doi:10.2478/abm-2023-0068

Figures & Tables

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

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

Figures & Tables

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

Different properties of various POCT devices

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