Lateral flow assays (LFAs) are popular for diagnostic applications owing to their quick response time, intuitiveness, and affordable cost. However, traditional LFAs are frequently limited by restrictions in specificity, sensitivity, and quantitative precision, typically delivering only qualitative results. To overcome these obstacles, sophisticated technologies are required to boost LFA performance and broaden their diagnostic abilities.
This article showcases how incorporating Molecular Devices’ ScanLater® Western Blot Detection System with Bright-Dtech™ nanoparticles, a proprietary technology from Poly-Dtech, effectively addresses the inherent limitations of traditional LFAs.
Originally designed for high-sensitivity fluorescence detection in Western blotting, the ScanLater® system can be repurposed for significantly enhanced lateral flow assessment, especially when paired with Bright-Dtech™ technology.
Bright-Dtech™ nanoparticles provide distinct advantages for LFAs thanks to their unique lanthanide-based probes, which deliver good brightness, photostability, and low background interference–crucial factors for sensitive and precise fluorescence-based detection. These nanoparticles ensure signal intensity remains robust, enabling precise quantification even at low analyte concentrations.
Benefits
- Bright-Dtech™ nanoparticles paired with ScanLater® technology provide excellent sensitivity compared to standard LFAs.
- Accurate fluorescence intensity quantification enables quantitative LFAs with precise analyte concentration determination.
- ScanLater® technology allows multiplexed evaluation of multiple test strips for boosting throughput and efficiency in high-volume workflows.
By incorporating the ScanLater® system’s quantitative fluorescence measurement abilities with the improved signal stability and brightness of Bright-Dtech™ probes, this method extends LFA analytical performance beyond traditional limitations.
To highlight the utility of this combined technology, this study presents an LFA specifically designed to quantitatively detect human lactate dehydrogenase (h-LDH). This enzyme plays a key role in cellular metabolism, and its quantification serves as a valuable biomarker of tissue damage.
High h-LDH levels signify cell membrane disruption and are linked to conditions including hemolysis, liver diseases, myocardial infarction, and cancer. In oncology, LDH also serves as a prognostic marker, with elevated levels typically reflecting tumor progression and poor outcomes.
This example showcases the exceptional accuracy, sensitivity, and dependability of this cutting-edge technique, demonstrating its applicability to high-precision diagnostic development and testing across diverse research and lab environments.
Figure 1. Depiction of the LFIA assay for detecting h-LDH using a non-competitive assay format with the Bright-Dtech™-614 Eu nanoparticles (EuNPs) as signal reporters. When excited at 340 nm, these EuNPs emit red fluorescence at 614 nm, which is detected in time-resolved mode. Image Credit: Molecular Devices UK Ltd
Benefits of Bright-Dtech Nanoparticles + ScanLater Technology
- Quantitative LFA: The integration of Bright- Dtech™ nanoparticles with ScanLater® technology enables accurate fluorescence intensity quantification, allowing for precise analyte concentration determination through the test-line-to-control-line (TL:CL) ratio.
- Elevated sensitivity: Bright-Dtech™ nanoparticles improve detection sensitivity owing to their prolonged fluorescence lifetime, allowing low analyte concentrations to be reliably quantified.
- Decreased background noise: The time-resolved fluorescence (TRF) abilities of ScanLater® technology considerably minimize background interference, delivering clearer and more precise signal detection.
- Superior sensitivity compared to standardLFAs: Combining Bright-Dtech™ nanoparticles and ScanLater® technology boosts analytical performance, exceeding the sensitivity of conventional LFAs.
- Multiplexed analysis: The ScanLater® system enables concurrent evaluation of multiple test strips, improving throughput and efficiency in high-volume diagnostic workflows.
- Flexible applications: This technology can adapt to a wide variety of analytes and sample types, such as plasma, serum, saliva, cells, and water. This capability makes it well-suited for various applications across research, veterinary, and even agri-food settings.
Assay Principle
Using Bright-Dtech™ nanoparticles, researchers designed a dipstick LFA for quantitative analyte detection, using h-LDH as a model.
In this assay, Bright-Dtech™ traditional detection probes, such as gold nanoparticles or conventional europium chelates, were replaced by lanthanide nanoparticles to achieve highly sensitive detection with improved fluorescence characteristics.
The test strip comprises a nitrocellulose membrane with two main detection lines: the test line (TL) and the control line (CL). The TL contains immobilized antibodies specific to the target antigen, which bind the analyte if present in the sample, capturing the nanoparticle-labeled complexes and producing a fluorescent signal proportional to the analyte concentration.
The CL acts as an internal control, ensuring assay validity by capturing excess nanoparticles and generating a fluorescence signal irrespective of analyte presence (Figure 1).
To accurately quantify the fluorescence signal at both the TL and CL after migration, researchers adapted the ScanLater® module, originally developed for high-sensitivity fluorescence detection in Western blot analysis. The system manages as many as 20 strips at the same time, improving assay throughput and reliability.
The SpectraMax® iD5 Multi-Mode Microplate Reader, equipped with the ScanLater system and time-resolved fluorescence (TRF) detection, is ideal for this application, as its optimized fluorescence reading parameters align with Bright-Dtech™ nanoparticle properties.
Note: The iD5 reader has been updated to the newer SpectraMax iD5e Multi-Mode Reader. This model offers identical features and performance, as well as optional SpectraMax aer Gas Mixer and advanced shaking features.
Fluorescent images of the lateral flow strips are obtained in TRF mode with a 0.05 ms delay between excitation (350 nm) and emission (616 nm). This setup substantially minimizes background noise from autofluorescence and other short-lived emissions, especially those coming from the nitrocellulose membrane, resulting in a clearer and more dependable quantitative readout.
The “gel analysis” tool, ImageJ (National Institutes of Health, Bethesda, MD), is used to quantify the fluorescence intensity at the TL and CL. This tool allows each strip to be selected and converts band intensities into peak profiles, with the region beneath the curve corresponding to fluorescence intensity.
To standardize results and support comparisons across multiple assays, the test-line-to-control-line ratio (TL:CL) is calculated, which serves as a normalized measure of analyte concentration.
Figure 2. Strips for the h-LDH LFA placed on the rack of the ScanLater™ system of the TRF SpectraMax® iD5 reader. Image Credit: Molecular Devices UK Ltd
Sensitivity and Dynamic Range
Calibration curves for h-LDH detection were produced by dispensing 5 μL of conjugated nanoparticles and 75 μL of serial h-LDH antigen dilution (ranging from 0 to 40 ng/ mL in migration buffer, n = 4) into the wells of a 96-well plate. The test strips were subsequently immersed and left to migrate for 20 minutes prior to being air-dried.
The strips were aligned in the ScanLater® system rack (Figure 2) and underwent scanning. The system then captured the images, followed by processing with ImageJ software for data extraction (Figure 3).
The resulting data was modeled using a five-parameter logistic (5PL) model in SoftMax Pro™ software (Molecular Devices), with an R2 value of 1. The system achieved a limit of detection (LoD) of 38 picograms/mL of h-LDH, demonstrating sensitivity comparable to that of commercial ELISA tests.
Thanks to test optimization, a preclinical study was performed by spiking h-LDH into serum. The acquired results, with a recovery rate (R%) ranging from 88% to 121%, highlight the robustness of this test and its accurate quantification capabilities in a complex matrix such as serum.
Figure 3. (A) Images of the EuNPs-based LFIA strips after detecting serial dilutions of h-LDH in working buffer. (B) Calibration curve plot representing the normalized signal in the TL achieved when detecting serial dilutions of h-LDH standard in working buffer with EuNPs-based LFIA (n = 4). Inset showing the calibration curve plot between 0.001 and 10 ng mL-1 of h-LDH. Image Credit: Molecular Devices UK Ltd
| Sample |
Expected [h-LDH]
(ng mL-1) |
Detected [h-LDH]
(ng mL-1) |
Recovery (%) |
| 1 |
0 |
<LoD |
– |
| 2 |
0.6 |
0.8 ±0.1 |
121 |
| 3 |
1.2 |
1.2 ±0.1 |
100 |
| 4 |
2.5 |
2.4 ±0.2 |
94 |
| 5 |
5.0 |
5.3 ±0.16 |
105 |
| 6 |
6.2 |
7.1 ±0.2 |
113 |
| 7 |
10.0 |
11.7 ±0.7 |
117 |
| 8 |
12.5 |
14.3 ±1.0 |
114 |
| 9 |
20.0 |
23.2 ±2.6 |
116 |
| 10 |
25.0 |
21.9 ±4.8 |
88 |
| Mean |
|
|
108 ±11 |
Figure 4. Recovery results when analyzing h-LDH spiked serum samples with EuNPs-based LFA. Image Credit: Molecular Devices UK Ltd
Conclusion
To summarize, the incorporation of Bright-Dtech™ nanoparticles and ScanLater® technology into LFAs represents substantial progress in quantitative evaluation.
The improved sensitivity of Bright-Dtech™ nanoparticles, as well as the excellent background-reduction abilities of ScanLater® technology, allows low analyte concentrations to be detected with high precision.
This potential is exemplified through the dipstick assay for human lactate dehydrogenase (h-LDH), exhibiting a limit of detection comparable to that of conventional ELISA assessments while providing the benefits of a quick and intuitive format.
Acknowledgments
Produced from materials originally authored by Caroline Cardonnel, PhD, European Applications Supervisor at Molecular Devices; Juliette Lajoux, MSc, Research Engineer, Biology at Poly-Dtech; Susana Brun, PhD, Biology Manager at Poly-Dtech; and Mohamadou Sy, PhD, Chemistry Manager at Poly-Dtech.
References and Further Reading
- Lajoux, J., et al. (2025). Breaking the picomolar barrier in lateral flow assays using Bright-Dtech™ 614 – Europium nanoparticles for enhanced sensitivity. Microchemical Journal, 209, p.112864. DOI:10.1016/j.microc.2025.112864. https://www.sciencedirect.com/science/article/abs/pii/S0026265X25002188?via%3Dihub.
About Molecular Devices UK Ltd
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To learn more about how Molecular Devices helps fast-track scientific discovery, visit www.moleculardevices.com.
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