Chen Jing, Feng Shaolong, Gao Fang, Grant Edward, Xu Jie, Wang Shuo, Huang Qian, Lu Xiaonan
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.
J Food Sci. 2015 Apr;80(4):N834-40. doi: 10.1111/1750-3841.12825. Epub 2015 Mar 3.
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.
我们制备了一种银纳米膜包覆的多孔阳极氧化铝（AAO），作为表面增强拉曼散射（SERS）活性基底，用于检测食品体系中的痕量氯霉素（一种具有代表性的抗生素）。在AAO合成过程中生成的有序铝模板作为一种图案化基质，在其上包覆的银膜复制图案化的AAO基质，形成二维有序纳米结构。我们使用原子力显微镜和扫描电子显微镜图像来确定这种纳米基底的形态，并通过紫外 - 可见反射对其局域表面等离子体共振进行表征。我们通过共焦显微拉曼光谱（782 nm激光）测量了这种纳米基底的SERS效应，发现其性能令人满意且一致，增强因子约为2×10⁴，氯霉素的检测限为7.5 ppb。我们应用主成分分析确定氯霉素的定量限为10 ppb。利用电磁场理论，我们建立了一个详细的数学模型来解释这种纳米基底拉曼信号增强的机制。通过简单的样品预处理和分离步骤，这种银纳米膜包覆的AAO基底能够检测牛奶中50 ppb的氯霉素，表明其作为一种可靠的SERS活性基底，在快速检测农产品和食品中的化学污染物方面具有良好的潜力。
