A novel ratiometric fluorescent approach for the modulation of the dynamic range of lateral flow immunoassays

The majority of lateral flow assays (LFAs) use single-color optical labels to provide a qualitative naked-eye detection, however this detection method displays two important limitations. First, the use of a single-color label makes the LFA prone to results misinterpretation. Second, it does not allow the precise modulation of the sensitivity and dynamic range of the test. To overcome these limitations, a ratiometric approach is developed. In particular, using anti-HIgG functionalized red-fluorescent quantum dots on the conjugate pad (as target dependent labels) and blue-fluorescent nanoparticles fixed on the test line (as target independent reporters), it is possible to generate a wide color palette (blue, purple, pink, red) on the test line. It is believed that this strategy will facilitate the development of LFAs by easily adjusting their analytical properties to the needs required by the specific application.