Long-Lived Phosphorescent CDs@SiO ₂ Coupled with Magnetic Quencher Fe ₃ O ₄ @PDA: A Dual-Mode Lateral Flow Immunochromatographic Assay for Sensitive Determination of Acetamiprid

Lateral flow immunochromatographic assay (LFIA) features advantages such as a rapid analysis process, interpretable detection results, and low cost, making it an effective method for on-site detection of pesticides. However, the existing LFIA technologies still face bottleneck issues, including strong background fluorescence interference from the substrate and insufficient detection sensitivity for low pesticide residue levels. Here, long-lived room-temperature phosphorescent carbon dots embedded in silica (CDs@SiO₂) were developed to overcome background fluorescence interference. Fe₃O₄ coated with dopamine (Fe₃O₄@PDA) was utilized for the enrichment of target pesticide molecules. Meanwhile, by virtue of the quenching effect of Fe₃O₄@PDA on CDs@SiO₂, colorimetric and phosphorescent dual-mode LFIA technology was designed for the detection of the pesticide acetamiprid. Through the integration of the advantages of CDs@SiO₂ and Fe₃O₄@PDA, the limit of detection (LOD) for acetamiprid was as low as 0.271 ng/mL, and satisfactory recoveries were achieved in real samples. This research breaks through the millisecond-level lifetime limitation in traditional time-resolved fluorescence immunoassays, providing novel insight for the development of labeling materials for LFIA.