Colorimetric and photothermal dual-mode lateral flow immunoassay based on Au-Fe 3 O 4 multifunctional nanoparticles for detection of Salmonella typhimurium

• Published in: Mikrochimica acta (1966) Vol. 190; no. 2; p. 57
• Main Authors: Wen, Cong-Ying, Zhao, Ling-Jin, Wang, Ying, Wang, Kun, Li, Hui-Wen, Li, Xiang, Zi, Min, Zeng, Jing-Bin
• Format: Journal Article
• Language: English
• Published: Austria 18.01.2023
• Subjects: Colorimetry; Immunoassay; Metal Nanoparticles; Multifunctional Nanoparticles; Reproducibility of Results; Salmonella typhimurium; Magnetic separation; Bacteria; LFIA strip
• ISSN: 1436-5073

Au-Fe O multifunctional nanoparticles (NPs) were synthesized and integrated with lateral flow immunoassay (LFIA) for dual-mode detection of Salmonella typhimurium. The Au-Fe O NPs not only combined excellent local surface plasmon resonance characteristics and superparamagnetic properties, but also exhibited good photothermal effect. In the detection, antibody-conjugated Au-Fe O NPs first captured S. typhimurium from complex matrix, which was then loaded on the LFIA strip and trapped by the T-line. By observing the color bands with the naked eyes, qualitative detection was performed free of instrument. By measuring the photothermal signal, quantification was achieved with a portable infrared thermal camera. The introduction of magnetic separation achieved the enrichment and purification of target bacteria, thus enhancing the detection sensitivity and reducing interference. This dual-mode LFIA achieved a visual detection limit of 5 × 10  CFU/mL and a photothermal detection limit of 5 × 10  CFU/mL. Compared with traditional Au-based LFIA, this dual-mode LFIA increased the detection sensitivity by 2 orders of magnitude and could be directly applied to unprocessed milk sample. Besides, this dual-mode LFIA showed good reproducibility and specificity. The intra-assay and inter-assay variation coefficients were 3.0% and 7.9%, and with this dual-mode LFIA, other bacteria hardly produced distinguishable signals. Thus, the Au-Fe O NPs-based LFIA has potential to increase the efficiency of pandemic prevention and control. Au-Fe O nanoparticle proved to be a promising alternative reporter for LFIA, achieving multifunctions: target purification, target enrichment, visual qualitation, and instrumental quantification, which improved the limitations of traditional LFIA.