Optical Detection of Foodborne Bacterial Pathogens using Nanosensors



Successful pathogen detection is crucial for public health as the threat of infectious disease is dramatically increasing due to bacteria developing resistance to anti-microbial drugs. Specifically, an increase in bacterial infections from foodborne pathogens such as Escherichia Coli and Salmonella have led to urgent demands for simpler, faster and more reliable detection methods to be developed. Surface enhanced Raman scattering (SERS) is an analytical technique which has gained a great deal of interest for biosensing due to its sensitivity, selectivity and multiplexing capabilities.

Our research goal was to develop an innovative SERS biosensor for the simultaneous detection of multiple pathogens associated with food contamination. Specifically, the research involved designing an optimised assay for the isolation and detection of Escherichia Coli, Salmonella Typhimurium and Staphylococcus Aureus simultaneously. SERS biosensors for the isolation and detection of each of the 3 bacterial strains have been developed. In addition, the bacterial strains can be discriminated between in a duplex and triplex assay.

The research data has been split into three folders:

i) Characterisation of Nanoparticle Conjugates
This folder contains all the data associated with the synthesis, functionalisation and characterisation of nanoparticles (NP) conjugated with bio-molecules (antibodies and lectins). The detection techniques used where Extinction spectroscopy, size, zeta and SERS analysis. . The SERS analysis was conducted using a Snowy Range instrument with a 532 nm laser excitation and acquisition times between 0.1 – 3s.

ii) Fixed Bacterial Imaging
This folder contains all the data associated with the bacterial mapping and imaging experiments. Single bacterial imaging and mapping was conducted to ensure the NP conjugates were binding efficiently to the surface of the bacteria. The dark field images and maps were acquired using a Renishaw Instrument. Specifically for the maps a 633 nm laser excitation and x100 objective was employed but with various laser powers, step sizes and acquisition times. See file names for specific details.

iii) Solution Assay
This folder contains all the data associated with the solution assay experiments. Initially the SERS assay was performed for each of the bacterial strains individually allowing for single pathogen detection but then additional experiments were conducted to investigate the multiplexing capabilities of this assay. In addition, an E. Coli concentration study and cross reactivity experiments were conducted. The Raman spectra were acquired using a Renishaw Instrument. Specifically a 532 nm laser excitation and x20 objective was focused into a 96 well plate containing 300 µL of the bacteria-NP conjugate solution. An acquisition time of 1s and laser power operating at 100% was employed. Note, various concentrations of bacteria were used in these studies from 10 million -10 CFUs but see folder and/or file names for specific information.

Embargo end date 15/01/18
Date made available16 Jan 2017
PublisherUniversity of Strathclyde

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