A dual-functional paper-based analytical device for ultrasensitive detection of peanut allergen-specific IgE.

Increasing attention has been caught by the allergy-related food safety issue. The rapid and sensitive diagnosing approaches are still in high demand for providing clinical reference. Paper-based analytical devices (PADs) are appealing candidates for allergy diagnosis and prediction due to their portability, stability, and operational easiness. However, the sensitivity of PADs needs to be further improved for the targets with low abundance. In addition to the complex signal amplifications, an alternative strategy that requires fewer reagents, steps, and shorter time is anticipated. (82) RESULTS: We report fluorescent PADs (FPADs) that can accumulate and detect the major peanut allergen glycoprotein Arachis hypogaea h2 (Ara h2)-specific IgE (sIgE). The FPADs are constructed by in-situ synthesis of blue-emissive carbon dots (BCDs) on the surface of cellulose paper, followed by the conjugation of Ara h2. After the capture of sIgE, a green-emissive carbon dots-labeled secondary anti-sIgE reporter (Ab2-GCDs) is assembled on FPADs. The detection relies on the sIgE concentration-dependent color variation of FPADs. In addition, the accumulation of sIgE is achievable by filtering the sample through FPADs, improving the assay sensitivity and efficiency. It is demonstrated that the limit of detection (LOD) is 15.7 ng/mL, evidently lower than the simple immersion-based assay (90.2 ng/mL). The excellent selectivity allows sIgE quantification in serum with high accuracy. (130) SIGNIFICANCE: By harnessing the outperforming sensing performance of the proposed FPADs, the rapid, accurate, and cost-efficient diagnosis and prediction of peanut allergy can be realized. In addition, the FPADs could serve as a universal sensing platform for varying targets by flexibly engineering the capture moieties on the surface of fluorescent paper. (50).