A dual-readout sandwich immunoassay based on biocatalytic perovskite nanocrystals for detection of prostate specific antigen

Nanozymes have been regarded as an excellent alternative for natural enzymes because of their high stability, low cost, and high activity. However, their use in disease diagnosis is still challenging, since the complex biological samples foul the nanozymes' surface and generate interference signals, thereby compromising the performance of nanozyme-based assays. Here, we report a dual-readout, CsPbBr3 NCs-based sandwich immunoassay for the detection of prostate specific antigen (PSA). Thanks to their excellent fluorescence and intrinsic peroxidase-like catalytic activity, the designed phospholipid-coated CsPbBr3 NCs (PL-CsPbBr3 NCs) served as an attractive dual signal generator (fluorescent and colorimetric), which is hardly achieved by other nanozymes. The Michaelis-Menten constant (KM) values of PL-CsPbBr3 NCs for H2O2 and tetramethylbenzidine are 2.85 mM and 1.42 mM, respectively. Meanwhile, the lipid shell around CsPbBr3 NCs not only greatly improves their aqueous stability, but also helps them resist the unspecific adsorption of biological impurities. Thus, the proposed dual-readout immunoassay enables precise, cost-effective, and anti-jamming detection of PSA in real serum samples with a low detection limit of 0.29 ng mL-1 (colorimetric) and 0.081 ng mL-1 (fluorescence). This enhanced immunoassay opens new insights for the application of perovskites in bioanalysis, especially for protein assay, holding great potential for disease diagnosis.