LAMP for point-of-care and point-of-use testing: bringing molecular diagnostics closer to the sample
A molecular result is most useful when it arrives while a decision can still be made.
In many molecular testing workflows, sample collection and analysis happen in different places. The sample travels to a central laboratory, then moves through preparation, amplification, detection and interpretation.
Point-of-care (POC) and point-of-use (POU) testing bring targeted molecular analysis closer to where the sample is collected. Depending on the application, that could mean a healthcare research setting, veterinary facility, food production site or environmental monitoring location.
Loop-mediated isothermal amplification, or LAMP, is particularly suited to this type of decentralized molecular testing. It amplifies nucleic acids at a constant temperature, reducing the thermal requirements of the amplification step and supporting compact detection systems [1,2].
But the amplification chemistry is only one part of the workflow. For LAMP to work effectively at the point of need, sample preparation, assay design, controls, detection and result interpretation all have to fit the environment where testing takes place.
What is LAMP?
Loop-mediated isothermal amplification is a nucleic acid amplification method first described by Notomi and colleagues in 2000 [1].
Unlike PCR, which repeatedly cycles through different temperatures, LAMP amplification takes place at a constant temperature, commonly around 60 to 65°C depending on the assay and enzyme system.
The method uses a strand-displacing DNA polymerase together with multiple primers designed to recognise several regions within the target sequence. The original LAMP method uses 4 primers recognising 6 target regions, while loop primers can be added to increase reaction speed [1,2]. Once the reaction starts, amplification can proceed rapidly without repeated heating and cooling cycles.
For laboratory PCR, precise thermal cycling is routine. At the point of use, removing that requirement can make a substantial difference to instrument design, power requirements and physical footprint.
Why LAMP fits point-of-care and point-of-use testing
A decentralized molecular test has to work under different constraints from a central laboratory assay.
Equipment may need to be small. Users may have less time for manual processing. Results may be required during the same visit, sampling round or operational shift.
LAMP addresses several of these constraints. Constant-temperature amplification can reduce the complexity of the heating system. Amplification can often be completed within tens of minutes. And LAMP can be combined with several detection formats, including fluorescence, turbidity and colorimetric readouts [2,3].
Colorimetric detection is particularly relevant to compact molecular systems. Changes produced during amplification can be monitored optically without relying on the fluorescence architecture commonly associated with real-time PCR instruments.
Together, these characteristics make LAMP an attractive technology for rapid molecular testing outside conventional centralized laboratories.
The practical performance of a system still depends on much more than amplification speed.
Sample preparation can determine the entire workflow
A 30-minute amplification reaction has limited value if preparing the sample requires another hour of laboratory work.
Biological, food and environmental samples contain very different mixtures of cells, proteins, salts, polysaccharides and other substances. Some can interfere with nucleic acid amplification.
LAMP has shown tolerance to several amplification inhibitors, which has encouraged research into simplified and direct testing workflows [3]. The degree of tolerance varies with the assay, target and sample matrix. This makes sample preparation one of the key design questions for point-of-use molecular testing.
A workflow intended for decentralized use may need to reduce centrifugation, manual liquid handling or lengthy nucleic acid purification. It also has to release enough target nucleic acid for reliable detection while controlling substances that could affect the reaction.
The practical unit therefore becomes the sample-to-result workflow, rather than the amplification reaction alone.
Where is LAMP used for point-of-need testing?
Research into LAMP-based point-of-care testing has expanded across infectious disease detection, with assays developed for bacterial, viral and parasitic targets [3,4].
The same technical characteristics are relevant beyond human health.
Veterinary testing
Animal samples are often collected away from centralized molecular laboratories. Portable or compact LAMP systems can support targeted molecular testing closer to veterinary clinics, farms and other animal health settings.
Food testing
Food laboratories and production environments frequently need targeted answers within operational timeframes. Isothermal amplification can support molecular screening approaches where sending every sample through a centralized workflow may add unwanted delay.
Environmental monitoring
Water and wastewater surveillance involve distributed sampling locations and large numbers of samples. LAMP-based methods can support targeted screening closer to sampling sites or local testing facilities, depending on the analytical question and sample preparation requirements.
Across these applications, the same principle applies: shorten the distance between sample collection and molecular information.
What are the limitations of LAMP?
LAMP simplifies one important part of molecular testing, but careful assay design remains essential.
The method uses several primers that recognise multiple regions of the target sequence. This can provide high sequence specificity, while also making primer design more demanding than for many conventional PCR assays [1,2].
Non-specific amplification and carryover contamination also require attention. High amplification efficiency can produce large amounts of DNA, so closed reaction formats and appropriate workflow controls become especially important.
Multiplex testing adds another technical challenge. A single LAMP reaction can be designed around a specific target, but detecting several targets from one sample requires a system that can separate reactions, signals or both. The practical multiplexing strategy therefore depends on the assay format and detection system.
These considerations matter when moving molecular testing closer to the point of use. A simpler instrument still needs carefully designed chemistry, controls and interpretation.
From LAMP chemistry to a decentralized molecular workflow
This sample-to-result thinking sits behind the InviDx® System.
InviDx® is a compact molecular testing platform developed for applications in decentralized testing, research and surveillance environments. The system combines LAMP amplification with colorimetric detection and automated qualitative result interpretation.
Compatible test kits use prefilled 12-well reaction strips containing lyophilized, predefined LAMP reaction mixes. Depending on the test panel, a strip can analyse up to 10 predefined target reactions from one sample, alongside positive and negative controls.
Amplification and detection typically take 30 to 45 minutes. Applicable workflows are designed to move from sample collection to result in less than 60 minutes.
Results are processed through the InviDx® Hub, a web-based application that applies assay-specific analysis rules and provides standardized qualitative interpretation.
Current applications include the InviScreen® UTI Pathogen Panel, which targets 10 predefined bacterial targets associated with urinary tract infections, and the InviScreen® AMR Gene Panel, designed to detect selected antimicrobial resistance-associated genes from previously isolated DNA across One Health research and surveillance contexts.
Bringing molecular testing closer to the sample
LAMP gives developers a practical route towards smaller molecular testing systems and shorter testing workflows.
Its constant-temperature amplification reduces thermal demands. Different optical readouts can support compact detection formats. And reaction times can fit applications where waiting for a conventional centralized workflow would delay the information being sought.
The strongest point-of-care and point-of-use systems treat LAMP as one part of a complete process.
Sample preparation has to suit the matrix. Controls have to work in the same format. Results need consistent interpretation. And the entire workflow has to make sense in the environment where the sample is collected.
When those pieces come together, molecular testing can move considerably closer to the point where the result becomes useful.
[1] Notomi T, Okayama H, Masubuchi H, et al. Loop-mediated isothermal amplification of DNA. Nucleic Acids Research. 2000;28(12):e63. doi:10.1093/nar/28.12.e63.
[2] Becherer L, Borst N, Bakheit M, Frischmann S, Zengerle R, von Stetten F. Loop-mediated isothermal amplification (LAMP): review and classification of methods for sequence-specific detection. Analytical Methods. 2020;12:717–746. doi:10.1039/C9AY02246E.
[3] Moehling TJ, Choi G, Dugan LC, Salit M, Meagher RJ. LAMP diagnostics at the point-of-care: emerging trends and perspectives for the developer community. Expert Review of Molecular Diagnostics. 2021;21(1):43–61. doi:10.1080/14737159.2021.1873769.
[4] Park JW. Principles and applications of loop-mediated isothermal amplification to point-of-care tests. Biosensors. 2022;12(10):857. doi:10.3390/bios12100857.