Staphylococcal enterotoxin B (SEB) in food is a serious health risk, making rapid and accurate detection methods essential. Herein, we synthesized a magnetic plasmonic blackbody, Fe₃O₄@Au/PDA, by coating a gold/polydopamine (Au/PDA) layer onto an Fe₃O₄ core. This Fe₃O₄@Au/PDA exhibits broadband absorption, excellent stability, and rapid magnetic response, making it ideal for use as a magnetic separation tool and colorimetric signal amplifier. We integrated Fe₃O₄@Au/PDA into a lateral flow immunoassay (LFIA) for ultrasensitive SEB detection, combining magnetic enrichment with enhanced colorimetric signal output. The Fe₃O₄@Au/PDA-based LFIA achieved a detection limit of 0.19 ng/mL, approximately 41 times lower than traditional gold nanoparticle-based LFIA. Its real-world applicability was tested in various food samples (milk, milk powder, apple juice, and lettuce) with recoveries between 82.4 % and 111.2 % and a coefficient of variation below 12.6 %. Collectively, the designed Fe₃O₄@Au/PDA shows great promise as a novel multifunctional signal amplification label, advancing the design and development of ultrasensitive LFIA for various fields, such as food safety detection.

中文翻译：

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磁性等离子体黑体增强葡萄球菌肠毒素 B 侧流免疫测定


食品中的葡萄球菌肠毒素 B （SEB） 是一种严重的健康风险，因此必须采用快速准确的检测方法。在此，我们通过在 Fe₃O₄ 核上涂覆金/聚多巴胺 （Au/PDA） 层，合成了磁性等离子体黑体 Fe₃O₄@Au/PDA。该 Fe₃O₄@Au/PDA 具有宽带吸收、出色的稳定性和快速的磁响应，非常适合用作磁性分离工具和比色信号放大器。我们将 Fe₃O₄@Au/PDA 整合到侧流免疫测定 （LFIA） 中，用于超灵敏的 SEB 检测，将磁富集与增强的比色信号输出相结合。基于 Fe₃O₄@Au/PDA 的 LFIA 实现了 0.19 ng/mL 的检测限，比传统的基于金纳米颗粒的 LFIA 低约 41 倍。在各种食品样品（牛奶、奶粉、苹果汁和生菜）中测试了其实际适用性，回收率在 82.4% 到 111.2% 之间，变异系数低于 12.6%。总的来说，设计的 Fe₃O₄@Au/PDA 作为一种新型多功能信号放大标记物显示出巨大的前景，推动了用于食品安全检测等各个领域的超灵敏 LFIA 的设计和开发。