Multiplex Lateral Flow Assays: Paving the Way for High-throughput Point-of-Care Testing

A patient rushes into the emergency room displaying symptoms of sepsis—a fast diagnosis is crucial. Here, multiplex lateral flow assays (LFAs) become lifesavers, allowing clinicians to quickly detect multiple sepsis biomarkers. But making these tools widely available requires addressing both performance issues as well as the cost of development.

^{This article is posted on our Science Snippets Blog}

LFAs and the allure of multiplexing 

LFAs are convenient, portable devices designed for quick diagnostic tests right at the hospital bedside or even at home. They operate on immunoassay principles, capturing target molecules as they move across a porous membrane by capillary action.  

Each LFA device includes this active membrane, along with extra layers that help introduce the sample and soak up any excess, all within a sturdy frame that delivers reliable results every time. The probe, typically coupled with micro- or nanoparticles, provides the visual readout. 

Multiplexing in an LFA is a game-changer, allowing a single sample to be screened for multiple targets in one go. It saves time and simplifies the whole testing process. Plus, it's more economical for point-of-care testing scenarios, cutting down on the amount of sample and reagents needed. 

The Challenge of Sensitivity and Affordability

A major challenge in point-of-care testing is finding the right balance between sensitivity and cost-effectiveness. For multiplex LFAs, the goal is to use fewer costly materials, such as antibodies, without sacrificing the test's performance. Obtaining patient samples is not always easy or inexpensive, so tests that yield more data from a small sample volume are advantageous.  

Additionally, using fewer samples reduces variability, further enhancing the test's reliability. Shifting from traditional line-based to dot-based lateral flow assays is one way to address these challenges. 

 Another vital aspect is the precise and controlled dispensing of small liquid volumes, typically in the microliter or nanoliter range, within LFA devices. Advances in microdispensing technology play a critical role, ensuring that samples, like blood or saliva, are applied uniformly onto the test strip. This uniformity is crucial for boosting the reliability and accuracy of the test results. 

An Innovative Platform for Multiplex LFAs

Diagnostic manufacturers aiming to improve assay performance while controlling costs can benefit from the latest advancements in microdispensing and membrane technology, like Unisart StructSure^®. This membrane combines multiple flow channels on a single lateral flow strip, offering test miniaturization and multiplexed semi-quantitative analysis.

Its dot-based design has some advantages over the line-based format for multiplex assays. First, it cuts down on the amount of expensive capture antibodies needed—by about 95%. Second, there is less risk of cross-reactivity, since each dot can be optimized for its intended analyte. 

Additionally, enhanced flow dynamics really helps with analyte and antibody interactions in the LFA. The channels are also more efficient for sample movement, requiring less volume to cover the same distance. Aside from faster test times and better sensitivity, this is beneficial when samples are scarce.

Case Study: Sepsis Multiplex LFA

A compelling case study from the company SCIENION showcases the application of multiplex LFA in detecting sepsis biomarkers C-reactive protein (CRP) and procalcitonin (PCT). By using dot-based dispensing technology and the Unisart^® StructSure membrane, the assay showed improved performance compared to traditional tests.
The structured membrane's flow dynamics and the precision microdispensing technology produced a higher signal intensity and a more reproducible assay. This is critical for a condition like sepsis, where early detection and accurate monitoring of biomarker levels are essential for patient management.

Looking ahead, the potential impacts of multiplex LFAs on global health care will undoubtedly be profound. Further, advancements in reader technology will help make the quantification and kinetic analysis of these assays more straightforward, further enhancing opportunities in various settings, from clinical laboratories to home testing.