Europium(<scp>III</scp>) Complex Loaded Polystyrene‐Maleic Anhydride Microspheres: Preparation, Post‐Treatment Modification, and Application in Monkeypox Antigen Detection via Lateral Flow Immunoassays

ABSTRACT In this investigation, we synthesize polystyrene‐maleic anhydride microspheres (PSMA) via a high‐temperature soap‐free emulsion polymerization method for the first time, as far as we know. This method eliminates the need for surfactants, offering a more efficient and refined process. Additionally, the polymerization is conducted without protective gases, accelerating the reaction kinetics compared to conventional methods. The microspheres are then treated with an alkaline solution to enhance their ability to load the Europium complex, improving detection sensitivity. Unlike previous methods that require functionalized monomers, this approach uses a simple alkaline treatment, making it more accessible and scalable. The fluorescence properties of the modified microspheres show significant improvements in intensity. These microspheres are used in a flow immunochromatographic assay for rapid monkeypox virus (MPVX) detection, demonstrating superior sensitivity, faster detection times, and a streamlined workflow compared to traditional methods. This study highlights the potential of these fluorescent microspheres for advancing immunodiagnostic assays and offers a promising approach for rapid, cost‐effective detection of infectious diseases.