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

Abstract

Escherichia coli O157:H7 is a common harmful foodborne pathogen that can cause severe diseases at low infectious doses. Traditional lateral flow immunoassay (LFIA) for the rapid screening of E. coli O157:H7 in food suffers from low sensitivity due to its dependence on 20-to 40-nm gold nanoparticles (AuNP) with insufficient brightness as labels. To address this issue, we reported for the first time the successful synthesis of gold superparticles (GSP) by encapsulating numerous small AuNP into a polymer nanobead using an evaporation-induced self-assembly method. Results indicated that the resultant GSP exhibited remarkably enhanced absorbance compared with the most widely used 40 nm AuNP in LFIA. In addition, the absorbance of GSP could be easily tuned by varying GSP sizes. Under optimized conditions, we achieved a rapid and sensitive determination of E. coli O157:H7 in milk with a detection limit of 5.95 × 10 2 cfu/mL when using the GSP with a size of 342 nm as LFIA signal reporters, exhibiting improvement of approximately 32-fold relative to the conventional 40 nm AuNP-LFIA method. We further demonstrated the selectivity, accuracy, reliability, and practicality of the proposed GSP-LFIA strip. In summary, this work offers a new strategy for improving LFIA sensitivity using assembled GSP as markers and demonstrates huge potential in rapidly and sensitively detecting foodborne pathogens.

Lateral Flow Strip Biosensors for Foodborne Pathogenic Bacteria via Direct and Indirect Sensing Strategies: A Review

“…For example, Li et al synthesized a 342 nm gold superparticle by encapsulating oleylamine-AuNPs into polymer nanobeads. 34 The limit of detection (LOD) of gold superparticle-based LFSB for E. coli O157:H7 in milk was 5.95 × 10 2 colony forming units (CFU)/ mL, which was approximately 32-fold lower than that of a conventional 40 nm AuNP-based LFSB. Nanozymes with enzyme-like catalytic ability are widely used in bioassays to enhance colorimetric signals because they can catalyze the reaction of H 2 O 2 and chromogenic reagents such as 3,3′,5,5′tetramethylbenzidine (TMB).…”

“…To improve the detection sensitivity, many novel nanomaterials and signal amplification methods have been applied to antibody-based LFSBs. For example, Li et al synthesized a 342 nm gold superparticle by encapsulating oleylamine-AuNPs into polymer nanobeads . The limit of detection (LOD) of gold superparticle-based LFSB for E.…”

Review of recent advances in improved lateral flow immunoassay for the detection of pathogenic Escherichia coli O157:H7 in foods

“…The limit of detection was ∼5 × 10 5 cfu/ml for standard bacteria solutions. Li et al (2020) demonstrated the synthesized gold superparticles (GSP) by encapsulating numerous small AuNPs into a polymer nanobead using an evaporation‐induced self‐assembly method. The resultant GSP exhibited remarkably enhanced absorbance compared with the most widely used 40 nm AuNPs in LFIA.…”

A gold nanoparticle based colorimetric sensor for the rapid detection of Yersinia enterocolitica serotype O:8 in food samples

“…Immunoassays are based on the specific binding between antibodies and antigens on the surface of target bacteria. [13][14][15] Enzyme-linked immunosorbent assay (ELISA) and colloidal gold immunochromatographic strip test (ICST) are accurate and highly specific. [16][17][18] Luciani et al developed a capture ELISA for the detection of Y. enterocolitica O:8 in food matrices.…”