Quantum Dots Instead of Dyes: Scientists Find a New Way to Diagnose Allergies
Researchers from Russia and France have increased the sensitivity of allergy chips using quantum dots. The technology could help detect allergies at earlier stages, when antibody levels in the blood are still low.
Scientists from the National Research Nuclear University MEPhI, Sechenov University and the University of Reims Champagne-Ardenne in France have found a way to improve the sensitivity of allergy tests using light-emitting nanocrystals. In experiments, the nanocrystals produced more stable light than conventional fluorescent dyes, and the accumulated signal was 10 times stronger.
The Elusive Nature of Allergies
Allergies can go undetected for a long time while causing considerable physical and emotional distress. About 20% to 30% of the world’s population is affected, and it is not always clear what triggers symptoms such as watery eyes, elevated body temperature and inflammation of the mucous membranes. Pollen, animal dander, household dust and food ingredients can all trigger an allergic reaction.
To choose preventive measures and treatment, doctors need to identify exactly what a patient’s immune system is reacting to. They do this by analyzing blood serum for allergen-specific immunoglobulin E (IgE). These are the antibodies involved in allergic reactions.
How Allergy Chips Work
Allergy chips are one tool used in diagnosis. A small glass or silicon chip holds an array of allergens, allowing a single test to check a patient’s response to multiple substances. If the patient’s serum contains matching antibodies, they bind to the allergens on the chip’s surface. Special probes carrying fluorescent labels then detect these complexes by glowing under laser light.
At this stage, a technical problem arises.: conventional organic dyes gradually lose their brightness under irradiation. As the signal weakens, it becomes harder to reliably detect small amounts of antibodies. This matters especially when researchers need to identify low concentrations of biomarkers and obtain more detailed information about an allergic response.
Nanocrystals Keep Glowing Longer
The research team proposed replacing conventional dyes with quantum dots – inorganic nanocrystals that emit light when excited by a laser. For the experiments, the researchers selected green-emitting QD565 quantum dots and compared them with DyLight550, a commercially available fluorescent dye that operates in a similar spectral range.
The researchers attached both labels to special probes designed to recognize complexes formed by immunoglobulin E and allergens. They then tested the probes on allergy chips, comparing fluorescence intensity and signal stability under different laser exposure conditions.
The results showed that the quantum dots glowed about twice as brightly as the standard dye. They also maintained stable fluorescence after 30 minutes of laser irradiation, while the organic dye’s signal weakened substantially over the same period. This stability makes it possible to use signal accumulation: the instrument records the nanocrystals’ response over an extended period and then adds up the measurements. This approach could improve the detection of small amounts of antibodies.
A Life With Fewer Allergens
The technology could give doctors and patients more detailed test results. The more reliably a test can capture a weak signal, the better its chances of detecting antibodies that a conventional test might miss. That could help doctors identify the cause of an allergy earlier and choose treatment tailored to an individual patient.
However, a brighter fluorescent label does not automatically make a test ready for clinical use. Before the method can be used in routine diagnostics, researchers need to test it on a range of samples, confirm that the results are reproducible and determine how well it performs under everyday conditions, not just in the laboratory. The next step is to refine the test system for use with quantum dots.
Potential Applications and Export Prospects
Quantum dots could be useful beyond allergy chips. They are bright, resist laser-induced signal loss and can be measured over extended periods to accumulate a stronger signal. These properties make them promising labels for other highly sensitive tests. In the future, the nanocrystals could become part of sensor platforms designed to detect a range of biological markers in the body.
The technology also has export potential. Laboratories worldwide need highly sensitive diagnostic tools, and stable fluorescent labels could attract interest from international test-system manufacturers. If the Russian technology proves its performance in further testing, it could have a path to international markets.
