A paper-based ELISA for rapid sensitive determination of anaphylaxis-related MRGPRX2 in human peripheral blood

Mas-related G-protein-coupled receptor X2 (MRGPRX2) has recently been reported to be associated with anaphylaxis. Detection of MRGPRX2 levels in human peripheral blood might serve as a powerful tool for predicting the predisposition of patients to anaphylactic reactions. For rapid measurement of MRGPRX2, we established a paper-based double-antibody sandwich enzyme-linked immunosorbent assay (ELISA) using mouse monoclonal antibody and horseradish peroxidase (HRP)-labelled rabbit polyclonal antibody as capture antibody and detection antibody, respectively. We avoided chemical functionalization of the cellulose paper by introducing bovine serum albumin (BSA) to provide COOH and NH₂ groups for covalent immobilization of the capture antibody. Through amide condensation, a two-layer immobilization strategy was applied with BSA-BSA and BSA-capture antibody networks as the first and second layers, respectively. This strategy improved the quantity, activity and stability of the immobilized antibody. We then established a paper-based ELISA to detect MRGPRX2 in human peripheral blood. Our method is less laborious, easier to implement, and more cost-effective than conventional ELISA, while offering similar sensitivity, specificity, and accuracy. Therefore, it could serve as an innovative clinical point-of-care diagnostic tool, especially in areas that lack advanced clinical equipment.