1 research outputs found
Immunomagnetic separation and Listeria monocytogenes detection with surfaceenhanced Raman scattering
Background/aim: We aimed to develop a rapid method to enumerate Listeria
monocytogenes (L. monocytogenes) utilizing magnetic nanoparticle based
preconcentration and surface-enhanced Raman spectroscopy measurements.
Materials and methods: Biological activities of magnetic
Au-nanoparticles have been observed to have the high biocompatibility,
and a sample immunosensor model has been designed to use avidin attached
Au-nanoparticles for L. monocytogenes detection. Staphylococcus aureus
(S. aureus) and Salmonella typhimurium (S. typhimurium) bacteria
cultures were chosen for control studies. Antimicrobial activity studies
have been done to identify bio-compatibility and bio-characterization of
the Au-nanoparticles in our previous study and capturing efficiencies to
bacterial surfaces have been also investigated.
Results: We constructed the calibration graphs in various population
density of L. monocytogenes as 2.2 x 10(1) to 2.2 x 10(6) cfu/mL and the
capture efficiency was found to be 75\%. After the optimization
procedures, population density of L. monocytogenes and Raman signal
intensity showed a good linear correlation (12 2 - 0.991) between 10(2)
to 10(6) cfu/ml, L. monocylogenes. The presented sandwich assay provides
low detection limits and limit of quantification as 12 cfu/mL and 37
cfu/mL, respectively. We also compared the experimental results with
reference plate-counting methods and the practical utility of the
proposed assay is demonstrated using milk samples.
Conclusion: It is focused on the enumeration of L. monocytogenes in milk
samples and the comparision of results of milk analysis obtained by the
proposed SERS method and by plate counting method stay in food
agreement. In the present study, all parameters were optimized to select
SERS-based immunoassay method for L. monocytogenes bacteria to ensure
LOD, selectivity, precision and repeatablity