Au@Pt core-shell nanoparticle-based lateral flow immunoassay for rapid detection of Porphyromonas gingivalis type II and IV FimA.

Porphyromonas gingivalis is a principal etiological agent of periodontal inflammation, with strains expressing type II and IV FimA fimbrial proteins exhibiting increased virulence. In this study, we developed a rapid and sensitive immunochromatographic assay for the detection of type II and IV FimA proteins, utilizing Au@Pt core-shell nanoparticles for catalytic signal amplification. Following optimization, the optimal antibody labeling quantities were determined to be 19.25 µg for FimA II and 22 µg for FimA IV, with a capture antibody concentration of 1.5 mg mL-1 for both test strips. Visual detection was achieved within 14 minutes. The limits of detection were established at 25 ng mL-1 for FimA II and 12.5 ng mL-1 for FimA IV prior to catalysis, with an approximate eight-fold decrease following catalytic amplification. The assay demonstrated excellent specificity and high concordance with PCR results in 112 clinical samples (AUCs: 0.9075 and 0.9544). This method offers a rapid and reliable analytical tool for the screening of high-risk P. gingivalis infections and has the potential to be adapted for the detection of other systemic diseases associated with P. gingivalis.