Gold decorated polystyrene particles for lateral flow immunodetection of Escherichia coli O157:H7

• Published in: Mikrochimica acta (1966) 2017-12, Vol.184 (12), p.4879-4886
• Main Authors: Jin, Seon-Ah, Heo, Yoojung, Lin, Li-Kai, Deering, Amanda J., Chiu, George T. -C., Allebach, Jan P., Stanciu, Lia A.
• Format: Article
• Language: English
• Subjects: Analytical Chemistry; Buffer solutions; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; E coli; Escherichia coli; Gold; Immunoassay; Microengineering; Nanochemistry; Nanoparticles; Nanotechnology; Pathogens; Polyethyleneimine; Polystyrene; Polystyrene resins; Reduction; Short Communication; Synthesis
• ISSN: 0026-3672; 1436-5073
• DOI: 10.1007/s00604-017-2524-5

Conventional lateral flow immunoassays for pathogen detection usually make use of gold nanoparticles to impart the color necessary for a readout. Unfortunately, these immunoassays require an extra-long time enrichment process before the detection. The synthesis of gold-decorated polystyrene particles (Au-PS), and their incorporation in a lateral flow immunoassay (LFIA) with improved sensitivity for detection of the model pathogen Escherichia coli O157:H7 ( E. coli O157:H7) were described in this article. The synthesis of the Au-PS particles occurred through the citrate reduction method. Then the particles underwent surface modification through coating with branched polyethylenimine, followed by grafting of the anti- E. coli O157:H7 antibody. The effect of Au-PS particle size and of the surface coverage on the detection limit of the assay was investigated. The Au-PS particles with 0.46 μm PS and 10% Au surface coverage achieved 500 CFU·mL −1 limit of detection (LOD) for E. coli O157:H7 in apple juice, ground beef, and spiked buffer solutions. Furthermore, these particles achieved 100 CFU·mL −1 LOD when the secondary a signal amplification reaction via gold reduction method was used. While the antibody-antigen interaction has a well-known role in detection, a precise optimization of the Au-PS particles used in LFIA assays can significantly affect performance. In our perception, Au nanoparticles coverage on sub-micron sized polystyrene particles was the critical factor that allowed reaching the reported low concentration of E. coli O157:H7 in real food samples. Graphical abstract Microstructure of gold-decorated polystyrene (Au-PS) particles and a schematic illustration for the detection of Escherichia coli O157:H7 by a lateral flow immunoassay strip containing the same.