Fabrication of SERS-active substrates using silver nanofilm-coated porous anodic aluminum oxide for detection of antibiotics.
We have developed a silver nanofilm-coated porous anodic aluminum oxide (AAO) as a surface-enhanced Raman scattering (SERS)-active substrate for the detection of trace level of chloramphenicol, a representative antibiotic in food systems. The ordered aluminum template generated during the synthesis of AAO serves as a patterned matrix on which a coated silver film replicates the patterned AAO matrix to form a 2-dimensional ordered nanostructure. We used atomic force microscopy and scanning electron microscopy images to determine the morphology of this nanosubstrate, and characterized its localized surface plasmon resonance by ultraviolet-visible reflection. We gauged the SERS effect of this nanosubstrate by confocal micro-Raman spectroscopy (782-nm laser), finding a satisfactory and consistent performance with enhancement factors of approximately 2 × 10(4) and a limit of detection for chloramphenicol of 7.5 ppb. We applied principal component analysis to determine the limit of quantification for chloramphenicol of 10 ppb. Using electromagnetic field theory, we developed a detailed mathematical model to explain the mechanism of Raman signal enhancement of this nanosubstrate. With simple sample pretreatment and separation steps, this silver nanofilm-coated AAO substrate could detect 50 ppb chloramphenicol in milk, indicating good potential as a reliable SERS-active substrate for rapid detection of chemical contaminants in agricultural and food products.
MOE Key Laboratory of Weak Light Nonlinear Photonics, Tianjin Key Laboratory of Photonics and Technology of Information Science, School of Physics, Nankai Univ, Tianjin, 300071, China; Food, Nutrition and Health Program, Faculty of Land and Food Systems, The Univ. of British Columbia, Vancouver, V6T 1Z4, Canada.
Jing
J
Chen
Shaolong
S
Feng
Fang
F
Gao
Edward
E
Grant
Jie
J
Xu
Shuo
S
Wang
Qian
Q
Huang
Xiaonan
X
Lu
D000535:Aluminum / Q000737:chemistry*; D000537:Aluminum Oxide / Q000737:chemistry*; D000900:Anti-Bacterial Agents / Q000032:analysis*; D002701:Chloramphenicol / Q000032:analysis; D005506:Food Contamination / Q000032:analysis*; D018625:Microscopy, Atomic Force; D008855:Microscopy, Electron, Scanning; D049329:Nanostructures / Q000737:chemistry*; D010087:Oxides; D016062:Porosity; D012834:Silver / Q000737:chemistry*; D018030:Silver Compounds; D013059:Spectrum Analysis, Raman / Q000379:methods*
D000900:Anti-Bacterial Agents; D010087:Oxides; D018030:Silver Compounds; D012834:Silver; D002701:Chloramphenicol; C040225:disilver oxide; D000535:Aluminum; D000537:Aluminum Oxide
contaminants; food analysis; food safety