1 / 12

SERS Detection in Complex Matrices

SERS Detection in Complex Matrices. Haynes group in collaboration with Lili He, Srinand Sreevatsan , and Ted Labuza (Department of Food Science). Why is SERS detection in complex matrices important?. Intentional or accidental adulteration of food supply

sine
Download Presentation

SERS Detection in Complex Matrices

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. SERS Detection in Complex Matrices Haynes group in collaboration with Lili He, SrinandSreevatsan, and Ted Labuza (Department of Food Science)

  2. Why is SERS detection in complex matrices important? • Intentional or accidental adulteration of food supply • Equipment contamination by allergens • Bioterrorism at vulnerable points of food supply chain • Need rapid, simple method of detecting foreign proteins in food supply • Aromatic amino acid bands ~950 and 1400 cm-1 shift • Amide I and III bands at 1600-1700 and 1200-1350 cm-1 shift, respectively • Usually done via ELISA or chromatography • Expensive • Slow • Done in lab (rather than on-site)

  3. SERS Detection in Complex Matrices Ovalbumin: egg white protein • Potentially allergenic • Proof-of-concept protein for generalizable • assay development Laser SERS SERS shift Ag dendrites Allowing analysis within co-cultures that simulate in vivo conditions. 2. Attach anti-OVA 3. Capture OVA 1. Adsorb protein G Antibody-based SERS detection immunoglobulin-binding protein from Streptococcal bacteria L. He, et al., Analytical Chemistry, 2011 http://chemistry.umeche.maine.edu/CHY431/Conformation5.html

  4. Ag Dendrite SERS Substrate Zn + 2AgNO3 2Ag + Zn(NO3)2 Ag dendrite UV-Vis spectrum L. He, et al. Journal of Raman Spectroscopy, 2009.

  5. OVA Detection in Milk Raman Intensity (AU) within class standard deviation 1700 1800 1600 1600 1500 1400 1200 1400 1300 1000 800 Raman Shift (cm-1) 2nd Derivative Transformation Raman Shift (cm-1) L. He, et al., Analytical Chemistry, 2011

  6. PCA of Ovalbumin Spectral Data 0.2 Ag dendrites Ag-protein G PC2 Score x 10 Ag-G-anti-OVA Ag-G-anti-OVA-OVA -0.3 -0.2 0.3 PC1 Score x 10 L. He, et al., Analytical Chemistry, 2011

  7. OVA Detection in Milk PBS Milk 0 and 1 µg/mL OVA 0 µg/mL OVA PC2 Score PC2 Score 0.1, 0.5, and 1 µg/mL OVA 5 µg/mL OVA PC1 Score PC1 Score L. He, et al., Analytical Chemistry, 2011

  8. DNA Aptamers as Capture Reagents http://aptamer.icmb.utexas.edu/index/php • Oligonucleotide sequences that bind to a target • Generated by repeated selection cycles • Relatively easy to manipulate • Raman spectra of DNA differ significantly from protein spectra

  9. Aptamer-Based SERS Assay • Target = ricin (potential bioterrorism agent) • No antidote • Need rapid assay for detection in food supplies • A-chain and B-chain (non-toxic B chain used to develop assay) L. He, et al., Chemical Science, 2011 www.bt.cdc.gov/agent/ricin E. Rutenber, et al. Proteins: Structure, Function, and Genetics, 1991

  10. Aptamer-Based SERS Assay * Ag-Ap * * * Raman Intensity (AU) Ag-Ap-Ricin 621 cm-1 Ag-Ricin 985 cm-1 Ag-Ap Ag-Ap Raman Intensity (AU) Ag-Ap-Ricin Ag-Ap-Ricin Ag-Ricin Ag-Ricin L. He, et al., Chemical Science, 2011

  11. Aptamer-Based SERS Assay 11 PC2 Score -8 -16 PC1 Score 19 Future work: capture analyte closer to SERS-active surface to improve signal L. He, et al., Chemical Science, 2011

  12. Aptamer Capture in Food Matrices Compare to 5 mg/mL using antibody approach L. He, et al., Chemical Science, 2011

More Related