Issue 18, 2012

The surface-enhanced Raman spectra of aflatoxins: spectral analysis, density functional theory calculation, detection and differentiation

Abstract

High-quality surface-enhanced Raman scattering (SERS) spectra of aflatoxin (AF) B1, B2, G1 and G2 have been acquired using silver nanorod (AgNR) array substrates fabricated by oblique angle deposition method. Significant vibrational peaks are identified on the argon plasma-cleaned substrates, and those peaks agree very well with the Raman spectra calculated by density function theory (DFT). The concentration-dependent SERS detection is also explored. The relationship between the concentration (C) of different AFs and the SERS intensity (I) of the Raman peak at Δν = 1592 cm−1 is found to follow the general relationship I = ACα, with α ranging from 0.32 to 0.46 for the four AFs. The limits of detection (LODs) reach 5 × 10−5 mol L−1 for AFB1, 1 × 10−4 mol L−1 for AFB2, and 5 × 10−6 mol L−1 for both AFG1 and AFG2 in bulk solution, or 6.17 × 10−16 mol/1.93 × 10−4 ng of AFB1, 1.23 × 10−15 mol/3.88 × 10−4 ng for AFB2, 6.17 × 10−17 mol/2.03 × 10−5 ng for AFG1, and 6.17 × 10−17 mol/2.04 × 10−5 ng for AFG2 per laser spot. Principal component analysis (PCA) is used to successfully differentiate these four different kinds of AFs at different concentrations up to their detection limits. The LODs obtained from PCA agree with the LODs obtained by using peak fitting method. With such a low detection limit and outstanding differentiation ability, we prove the possibility of utilizing the SERS detection system as a platform for highly sensitive mycotoxin detection.

Graphical abstract: The surface-enhanced Raman spectra of aflatoxins: spectral analysis, density functional theory calculation, detection and differentiation

Supplementary files

Article information

Article type
Paper
Submitted
20 Mar 2012
Accepted
25 Jun 2012
First published
25 Jun 2012

Analyst, 2012,137, 4226-4234

The surface-enhanced Raman spectra of aflatoxins: spectral analysis, density functional theory calculation, detection and differentiation

X. Wu, S. Gao, J. Wang, H. Wang, Y. Huang and Y. Zhao, Analyst, 2012, 137, 4226 DOI: 10.1039/C2AN35378D

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