Ultra-sensitive fluorescent immunoassay based on bright AIE nanoparticle for biomarkers detection and quantification

Fluorescence immunoassay (FIA) is one of the most immunoassay diagnosis methods in clinic for biomarker quantification in recent years. The development of reliable FIA strategy with high-sensitivity, large-rang and outstanding efficiency for biomarkers rapid diagnosis, especially in complicated samples, is still a great challenge. Herein, an ultra-sensitive FIA combined with magnetic separation was established to achieve efficient point-of-care diagnosis in quantitative behavior based on bright aggregation-induced emission nanoparticles (AIE NPs). By utilizing swelling method, AIE NPs with controllable size, relatively high luminescence efficiency and large Stokes shift were prepared, moreover, the obtained NPs also exhibit narrow size distribution and well-defined spherical morphology. Stability studies prove that AIE NPs not only possess quite high photostability, but also present good resistance towards harsh acid-alkaline steadily. By using AIE NPs as the reporter, a reliable and efficient FIA sensor was successfully constructed. The precise detection of C-reaction protein (CRP) antigen was acquired with the linear range of 0.5 ng·mL−1 ~ 1000 ng·mL−1 and the limit of detection (LOD) of 0.35 ng·mL-1, which is comparative with the conventional chemiluminescence immunoassays. Moreover, the whole detection operation could be accomplished within 10 min, which is relatively rapid and desirable for point-of-care diagnosis. In addition, this strategy also presented excellent specificity towards CRP antigens among various inflammatory antigens. These results confirm that AIE NPs-based FIA strategy provides an ideal and reliable approach for precise and quantitive biosensing of in vitro diagnostics.