title: Plasmonic Enzyme-Linked Immunosorbent Assay Using Nanospherical Brushes as a Catalase Container for Colorimetric Detection of Ultralow Concentrations of Listeria monocytogenes.
abstract: Plasmonic enzyme-linked immunosorbent assay (pELISA) based on catalase (CAT)-mediated gold nanoparticle growth exhibits ultrahigh sensitivity for detecting disease-related biomarkers using sandwich formats. However, the limit of detection (LOD) of this strategy for Listeria monocytogenes is only around 10(3) CFU/mL, which considerably exceeds the amount of L. monocytogenes commonly present in food products (<100 CFU/g). Herein, we report an improved pELISA method for detection of L. monocytogenes at ultralow concentrations with the sandwich formats using silica nanoparticles carrying poly(acrylic acid) brushes as a "CAT container" to increase enzyme loading for enhancing the detection signal. Under optimal conditions, the proposed pELISA exhibits good specificity and excellent sensitivity for L. monocytogenes with a LOD of 8 × 10(1) CFU/mL in 0.01 M phosphate-buffered saline, via a reaction that can be discriminated by the naked eye. The LOD obtained by this method was 2 and 5 orders of magnitude lower than that of conventional CAT-based pELISA and horseradish peroxidase (HRP)-based conventional ELISA, respectively. Coupled with large-volume immunomagnetic separation, the LOD for L. monocytogenes-spiked lettuce samples reached 8 × 10(1) CFU/g. The improved pELISA also exhibited a great potential in detecting a single cell of L. monocytogenes in 100 μL of solution.
authors.affiliation: College of Life Science, Nanchang University , Nanchang 330031, P. R. China.|State Key Laboratory of Food Science and Technology, Nanchang University , Nanchang 330047, P. R. China.
authors.forename: Rui
authors.initials: R
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Food Science and Technology, Nanchang University , Nanchang 330047, P. R. China.
authors.forename: Xiaolin
authors.initials: X
authors.lastname: Huang
authors.affiliation: State Key Laboratory of Food Science and Technology, Nanchang University , Nanchang 330047, P. R. China.
authors.forename: Hengyi
authors.initials: H
authors.lastname: Xu
authors.affiliation: College of Life Science, Nanchang University , Nanchang 330031, P. R. China.|State Key Laboratory of Food Science and Technology, Nanchang University , Nanchang 330047, P. R. China.
authors.forename: Yonghua
authors.initials: Y
authors.lastname: Xiong
authors.affiliation: Department of Biological and Agricultural Engineering, University of Arkansas , Fayetteville, Arkansas 72701, United States.
authors.forename: Yanbin
authors.initials: Y
authors.lastname: Li
mesh_terms: D002374:Catalase / Q000737:chemistry*; D003124:Colorimetry / Q000379:methods*; D004797:Enzyme-Linked Immunosorbent Assay / Q000295:instrumentation / Q000379:methods*; D005506:Food Contamination / Q000032:analysis; D018545:Lactuca / Q000382:microbiology; D008089:Listeria monocytogenes / Q000737:chemistry* / Q000254:growth & development; D012680:Sensitivity and Specificity
chemical_list: D002374:Catalase
keywords: Listeria monocytogenes; gold nanoparticle; nanospherical brushes; plasmonic enzyme-linked immunosorbent assay; signal amplifier