Development of Polyphenol–Metal Film-Modified Colored Porous Microspheres for Enhanced Monkeypox Antigen Detection

The Monkeypox virus (MPXV), a DNA virus classified under the Orthpoxvirus genus alongside variola virus, has recently garnered significant global health attention due to its increasing transmission and emerging genomic mutations. Point-of-care testing is essential for effective clinical response and outbreak mitigation. In this article, we developed a novel class of colored microspheres designed for application in a lateral flow immunoassay (LFIA) platform targeting MPXV-specific biomarkers. Polystyrene-maleic anhydride (SMA-MAA) microspheres were synthesized with a high-temperature soap-free emulsion polymerization optimized in our lab. Subsequent alkali and acid treatments were employed to introduce porosity into the microsphere matrix. Solvent Red 27 and Disperse Red 60 were incorporated via solvent-swelling and thermal-swelling methods, respectively, to generate high brightness (HB) carriers. A surface coating composed of a tannic acid–iron (TA–Fe3⁺) coordination complex was applied to form a stable metal–polyphenol film (MPF). This coating not only minimized dye leaching by establishing a robust shell but also improved dye distribution, thereby enhancing overall color intensity. The final HB-LFIA system, configured in a sandwich immunoassay format, demonstrated favorable sensitivity and linear detection range for Monkeypox antigen, indicating strong potential for clinical diagnostic use.