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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

The correlation between the relative Raman intensity of the 735 cm–1 peak and the concentration of E. coli cells in the sample. The relative Raman intensity was calculated using the 4-ATP peak at 1,079 cm–1 as internal reference, error bar indicates the standard errors of the mean from five independent runs.
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biosensors-03-00312-f006: The correlation between the relative Raman intensity of the 735 cm–1 peak and the concentration of E. coli cells in the sample. The relative Raman intensity was calculated using the 4-ATP peak at 1,079 cm–1 as internal reference, error bar indicates the standard errors of the mean from five independent runs.

Mentions: As shown in Figure 5, the 735 cm–1 bacterial peak became detectable at 102 CFU/mL E. coli concentration, comparable to that of high-end ELISA assay, without going through any washing steps. When E. coli concentration was lower than 102 CFU/mL (three were tested, 50 CFU/mL, 30 CFU/mL, 10 CFU/mL, respectively), the 735 cm−1 peak was not significantly different from that of the control (within Mcontrol ± 3σ), hence it was considered as indistinguishable from the control. The relative intensity of the 735 cm–1 peak, calculated with reference to the 1,079 cm–1 peak (representative peak of 4-ATP, which is determined by the number of nanoprobes, not the number of bacterial cells, stayed within Mcontrol ± 3σ for all samples investigated), is exponentially correlated to the concentration of bacterial cells in the sample, between 102 CFU/mL to 106 CFU/mL. A second peak at 985 cm−1 was also investigated. Similarly, the relative intensity of the 985 cm−1 peak calculated with reference to the 1,079 cm−1 peak, is exponentially correlated to the concentration of bacterial cells in the sample. Experiments were replicated five times with each concentration, and the standard errors of the mean for each concentration are also shown in Figure 6. The self-referencing assay potentially can be developed into a fast semi-quantitative assay for bacterial targets.


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)

The correlation between the relative Raman intensity of the 735 cm–1 peak and the concentration of E. coli cells in the sample. The relative Raman intensity was calculated using the 4-ATP peak at 1,079 cm–1 as internal reference, error bar indicates the standard errors of the mean from five independent runs.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

biosensors-03-00312-f006: The correlation between the relative Raman intensity of the 735 cm–1 peak and the concentration of E. coli cells in the sample. The relative Raman intensity was calculated using the 4-ATP peak at 1,079 cm–1 as internal reference, error bar indicates the standard errors of the mean from five independent runs.
Mentions: As shown in Figure 5, the 735 cm–1 bacterial peak became detectable at 102 CFU/mL E. coli concentration, comparable to that of high-end ELISA assay, without going through any washing steps. When E. coli concentration was lower than 102 CFU/mL (three were tested, 50 CFU/mL, 30 CFU/mL, 10 CFU/mL, respectively), the 735 cm−1 peak was not significantly different from that of the control (within Mcontrol ± 3σ), hence it was considered as indistinguishable from the control. The relative intensity of the 735 cm–1 peak, calculated with reference to the 1,079 cm–1 peak (representative peak of 4-ATP, which is determined by the number of nanoprobes, not the number of bacterial cells, stayed within Mcontrol ± 3σ for all samples investigated), is exponentially correlated to the concentration of bacterial cells in the sample, between 102 CFU/mL to 106 CFU/mL. A second peak at 985 cm−1 was also investigated. Similarly, the relative intensity of the 985 cm−1 peak calculated with reference to the 1,079 cm−1 peak, is exponentially correlated to the concentration of bacterial cells in the sample. Experiments were replicated five times with each concentration, and the standard errors of the mean for each concentration are also shown in Figure 6. The self-referencing assay potentially can be developed into a fast semi-quantitative assay for bacterial targets.

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