Separation and detection of multiple pathogens in a food matrix by magnetic SERS nanoprobes |
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Authors: | Yuling Wang Sandeep Ravindranath Joseph Irudayaraj |
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Institution: | (1) Physiological Sensing Facility, Bindley Biosciences Center and Birck Nanotechnology Center, Agricultural and Biological Engineering, Purdue University, 225 S. University Street, West Lafayette, IN 47907, USA; |
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Abstract: | A rapid and sensitive method was developed here for separation and detection of multiple pathogens in food matrix by magnetic
surface-enhanced Raman scattering (SERS) nanoprobes. Silica-coated magnetic probes (MNPs@SiO2) of ∼100 nm in diameter were first prepared via the reverse microemulsion method using cetyltrimethylammonium bromide as
a surfactant and tetraethyl orthosilicate as the silica precursor. The as-prepared MNPs@SiO2 were functionalized with specific pathogen antibodies to first capture threat agents directly from a food matrix followed
by detection using an optical approach enabled by SERS. In this scheme, pathogens were first immuno-magnetically captured
with MNPs@SiO2, and pathogen-specific SERS probes (gold nanoparticles integrated with a Raman reporter) were functionalized with corresponding
antibodies to allow the formation of a sandwich assay to complete the sensor module for the detection of multiple pathogens
in selected food matrices, just changing the kinds of Raman reporters on SERS probes. Here, up to two key pathogens, Salmonella enterica serovar Typhimurium and Staphylococcus aureus, were selected as a model to illustrate the probability of this scheme for multiple pathogens detection. The lowest cell
concentration detected in spinach solution was 103 CFU/mL. A blind test conducted in peanut butter validated the limit of detection as 103 CFU/mL with high specificity, demonstrating the potential of this approach in complex matrices. |
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