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A Self-Referencing Detection of Microorganisms Using Surface Enhanced Raman Scattering Nanoprobes in a Test-in-a-Tube Platform.

Xiao N, Wang C, Yu C - Biosensors (Basel) (2013)

Bottom Line: Anisotropic nanoparticles (i.e., silver nanocubes) were functionalized with target-specific antibodies and Raman active tags to serve as nanoprobes for the rapid detection of bacteria in a test-in-a-tube platform.The assessment through the dual signals (superimposed target and tag Raman signatures) supported a specific recognition of the targets in a single step with no washing/separation needed to a sensitivity of 102 CFU/mL, even in the presence of non-target bacteria at a 10 times higher concentration.The self-referencing protocol implemented with a portable Raman spectrometer potentially can become an easy-to-use, field-deployable spectroscopic sensor for onsite detection of pathogenic microorganisms.

View Article: PubMed Central - PubMed

Affiliation: Department of Agricultural and Biosystems Engineering, Iowa State University, Ames, IA 50011, USA. nxiao@iastate.edu.

ABSTRACT
Anisotropic nanoparticles (i.e., silver nanocubes) were functionalized with target-specific antibodies and Raman active tags to serve as nanoprobes for the rapid detection of bacteria in a test-in-a-tube platform. A self-referencing scheme was developed and implemented in which surface enhanced Raman spectroscopic (SERS) signatures of the targets were observed superimposed with the SERS signals of the Raman tags. The assessment through the dual signals (superimposed target and tag Raman signatures) supported a specific recognition of the targets in a single step with no washing/separation needed to a sensitivity of 102 CFU/mL, even in the presence of non-target bacteria at a 10 times higher concentration. The self-referencing protocol implemented with a portable Raman spectrometer potentially can become an easy-to-use, field-deployable spectroscopic sensor for onsite detection of pathogenic microorganisms.

No MeSH data available.


Related in: MedlinePlus

SERS spectra of silver nanoprobes functionalized with anti-E. coli antibodies (blue) incubated with E. coli (red) and Listeria (black). No bacterial-originated peaks can be observed when non-target species is integrated with the nanoprobes.
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biosensors-03-00312-f004: SERS spectra of silver nanoprobes functionalized with anti-E. coli antibodies (blue) incubated with E. coli (red) and Listeria (black). No bacterial-originated peaks can be observed when non-target species is integrated with the nanoprobes.

Mentions: Figure 4 shows the Raman spectra of Ag-4-ATP-Abs probe (Ag-nanocube functionalized with anti-E. coli antibodies) binding with E. coli and L. monocytogenes, respectively. Since bacteria cells were suspended in aqueous solution, they are constantly drifting in and out of the focal volume of the laser beam. To assure a meaningful SERS spectrum is acquired, the integration time was set to be 60 s, with the laser power set at 15 mW. Earlier reports suggested that at this power level and integration time, microbial samples tend to become graphitic and their spectroscopic characteristics may change dramatically [20]. However, in our experiment the cells were suspended in aqueous solution, and the SPR-induced heat damage seems to be alleviated. Also the cells were drifting in and out of the focal volume, and the actual laser exposure of individual cells seems not to have gone over the graphitic limit; evidenced by the lack of the D and G bands of graphene in the spectra.


A Self-Referencing Detection of Microorganisms Using Surface Enhanced Raman Scattering Nanoprobes in a Test-in-a-Tube Platform.

Xiao N, Wang C, Yu C - Biosensors (Basel) (2013)

SERS spectra of silver nanoprobes functionalized with anti-E. coli antibodies (blue) incubated with E. coli (red) and Listeria (black). No bacterial-originated peaks can be observed when non-target species is integrated with the nanoprobes.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4263577&req=5

biosensors-03-00312-f004: SERS spectra of silver nanoprobes functionalized with anti-E. coli antibodies (blue) incubated with E. coli (red) and Listeria (black). No bacterial-originated peaks can be observed when non-target species is integrated with the nanoprobes.
Mentions: Figure 4 shows the Raman spectra of Ag-4-ATP-Abs probe (Ag-nanocube functionalized with anti-E. coli antibodies) binding with E. coli and L. monocytogenes, respectively. Since bacteria cells were suspended in aqueous solution, they are constantly drifting in and out of the focal volume of the laser beam. To assure a meaningful SERS spectrum is acquired, the integration time was set to be 60 s, with the laser power set at 15 mW. Earlier reports suggested that at this power level and integration time, microbial samples tend to become graphitic and their spectroscopic characteristics may change dramatically [20]. However, in our experiment the cells were suspended in aqueous solution, and the SPR-induced heat damage seems to be alleviated. Also the cells were drifting in and out of the focal volume, and the actual laser exposure of individual cells seems not to have gone over the graphitic limit; evidenced by the lack of the D and G bands of graphene in the spectra.

Bottom Line: Anisotropic nanoparticles (i.e., silver nanocubes) were functionalized with target-specific antibodies and Raman active tags to serve as nanoprobes for the rapid detection of bacteria in a test-in-a-tube platform.The assessment through the dual signals (superimposed target and tag Raman signatures) supported a specific recognition of the targets in a single step with no washing/separation needed to a sensitivity of 102 CFU/mL, even in the presence of non-target bacteria at a 10 times higher concentration.The self-referencing protocol implemented with a portable Raman spectrometer potentially can become an easy-to-use, field-deployable spectroscopic sensor for onsite detection of pathogenic microorganisms.

View Article: PubMed Central - PubMed

Affiliation: Department of Agricultural and Biosystems Engineering, Iowa State University, Ames, IA 50011, USA. nxiao@iastate.edu.

ABSTRACT
Anisotropic nanoparticles (i.e., silver nanocubes) were functionalized with target-specific antibodies and Raman active tags to serve as nanoprobes for the rapid detection of bacteria in a test-in-a-tube platform. A self-referencing scheme was developed and implemented in which surface enhanced Raman spectroscopic (SERS) signatures of the targets were observed superimposed with the SERS signals of the Raman tags. The assessment through the dual signals (superimposed target and tag Raman signatures) supported a specific recognition of the targets in a single step with no washing/separation needed to a sensitivity of 102 CFU/mL, even in the presence of non-target bacteria at a 10 times higher concentration. The self-referencing protocol implemented with a portable Raman spectrometer potentially can become an easy-to-use, field-deployable spectroscopic sensor for onsite detection of pathogenic microorganisms.

No MeSH data available.


Related in: MedlinePlus