A One-Step Homogeneous Sandwich Immunosensor for Salmonella Detection Based on Magnetic Nanoparticles (MNPs) and Quantum Dots (QDs)

Abstract

Simple immuno-magnetic separation tandem fluorescent probes based on quantum dots-antibody (QDs-Ab) were developed to detect Salmonella with sensitivity of 500 cfu mL−1. With two monoclonal antibodies, which recognize different antigenic determinant on the surface of Salmonella, we prepared antibody-coated magnetic nanoparticles (MNPs) and conjugates of QDs-Ab. The immune-magnetic beads were verified with high enrichment efficiency for Salmonella (90%). A sandwich structure formed if the Salmonella solution was mixed together with immune-beads and QDs-Ab, and the fluorescent single from QDs was related to the amount of Salmonella. A linear response between fluorescence intensity and various concentrations of Salmonella (2.5 × 103 to 1.95 × 108 cfu mL−1) were observed with this proposed method. The total assay time for Salmonella was 30 min, and no cross-reaction to other microbial strains, such as Staphylococcus aureus, Escherichia coli (E. coli) and Escherichia coli O157:H7 (E. coli O157:H7), were found using this detection system. All our results showed that the simple homogeneous immunoassay could be applied in Salmonella screening without time-consuming extra-enrichment of bacteria.

Review on Biosensors for Food Safety

“…Several groups have reported the application of QDs for pathogen detection including Escherichia coli O157:H7 (Su and Li, 2004;Wang et al, 2012;Zhu et al, 2012), Salmonella (Kuang et al, 2013), Campylobacter jejuni (Bruno et al, 2009), Listeria monocytogenes (Wang et al, 2007), and avian influenza viruses (Chou et al, 2012). The application of QDs has also been extended to multiplexed detection based on immunoassay formats.…”

Magnetically optimized SERS assay for rapid detection of trace drug-related biomarkers in saliva and fingerprints

“…This work expands upon the idea that the aggregation of superparamagnetic metallic nanocomposites can be controlled by a magnet (Timonen et al, 2013). Additionally, the detection sensitivity of some methods in literature was optimized by the magnetic effect Ma et al, 2013;Kuang et al, 2013). In this paper, the utilization of a magnet to reversibly control AMN for generating a favorable density of hot spots via the optimization of aggregation is investigated, and the direct determination of trace amounts of drug-related biomarkers in saliva and fingerprints is studied using a portable Raman analyzer-AMN-based SERS technique.…”

Magnetic Bead‐Based Immunoassay Coupled with Tyramide Signal Amplification for Detection of Salmonella in Foods

“…The sensitivity of the developed assay was also compared to other recently reported, antibody-based detection assays for Salmonella. One recent study developing a sandwich immunoassay based on magnetic nanoparticles and quantum dots for detection of Salmonella reported the detection limit of 500 CFU/mL (Kuang et al, 2013). Another study using an immunochromatographic strip assay combined with signal amplification using liposome vesicles showed the detection limit to be 100 CFU/mL (Shukla et al, 2011).…”