Integrated gold superparticles into lateral flow immunoassays for the rapid and sensitive detection of Escherichia coli O157:H7 in milk

摘要

Escherichia coli O157:H7 is a common harmful foodbornepathogen that can cause severe diseases at lowinfectious doses. Traditional lateral flow immunoassay(LFIA) for the rapid screening of E. coli O157:H7 infood suffers from low sensitivity due to its dependenceon 20- to 40-nm gold nanoparticles (AuNP) with insufficientbrightness as labels. To address this issue, wereported for the first time the successful synthesis ofgold superparticles (GSP) by encapsulating numeroussmall AuNP into a polymer nanobead using an evaporation-induced self-assembly method. Results indicatedthat the resultant GSP exhibited remarkably enhancedabsorbance compared with the most widely used 40 nmAuNP in LFIA. In addition, the absorbance of GSPcould be easily tuned by varying GSP sizes. Under optimizedconditions, we achieved a rapid and sensitive determinationof E. coli O157:H7 in milk with a detectionlimit of 5.95 × 10~2 cfu/mL when using the GSP witha size of 342 nm as LFIA signal reporters, exhibitingimprovement of approximately 32-fold relative to theconventional 40 nm AuNP-LFIA method. We furtherdemonstrated the selectivity, accuracy, reliability, andpracticality of the proposed GSP-LFIA strip. In summary,this work offers a new strategy for improvingLFIA sensitivity using assembled GSP as markers anddemonstrates huge potential in rapidly and sensitivelydetecting foodborne pathogens.