Surface-enhanced Raman spectroscopy for trace detection of tetracycline and dicyandiamide in milk using transparent substrate of Ag nanoparticle arrays

Authors: MUHAMMAD, MUHAMMAD - University Of Science And Technology Of China; YAN, BIN - University Of Science And Technology Of China; YAO, GUOHUA - University Of Science And Technology Of China; Chao, Kuanglin - Kevin Chao; ZHU, GHUHONG - University Of Science And Technology Of China; HUANG, QING - University Of Science And Technology Of China

Submitted to: American Chemical Society Applied Nano Materials
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/10/2020
Publication Date: 12/20/2020
Citation: Muhammad, M., Yan, B., Yao, G., Chao, K., Zhu, G., Huang, Q. 2020. Surface-enhanced Raman spectroscopy for trace detection of tetracycline and dicyandiamide in milk using transparent substrate of Ag nanoparticle arrays. American Chemical Society Applied Nano Materials. https://doi.org/10.1021/acsanm.0c01389.
DOI: https://doi.org/10.1021/acsanm.0c01389

Interpretive Summary: Veterinary drugs such as Tetracycline (TC) and the grassland fertilizer Dicyandiamide (DCD) can end up as a residue contamination in milk products. To avoid human health risks from tainted dairy foods, rapid nondestructive detection methodologies to detect these contaminants are necessary. Slower, more complicated methods of chemical analysis can be used to further confirm analytical results if/as needed. Spectroscopic analysis required first the development of a silver nanoparticle layer on an aluminum oxide surface. TC and DCD is then detected on this surface layer by a technology called Surface Enhanced Raman Spectroscopy (SERS). Detection levels are 1 × 10-9 M and 1 × 10-7 M, for TC and DCS respectively. Lipids components in milk in this methodology do not interfere with contaminant detection even at these low levels. This study has demonstrated the effectiveness of the new sensing method to provide a practical and reliable platform for rapid contaminant detection in milk products which could greatly benefit the food industry and consumers.

Technical Abstract: Therapeutic use of veterinary drugs such as Tetracycline (TC), a broad spectrum antibiotic, has increased the risk of residue contamination in animal food products. Dicyandiamide (DCD) is a grassland fertilizer upon its detection in milk products was banned. To avoid human health risks from tainted dairy foods, rapid nondestructive detection methodologies are necessary. Herein, we fabricated silver nanoparticle (AgNP) arrays using the anodic aluminum oxide (AAO) template-assisted electrochemical deposition approach which formed a transparent and homogeneous substrate which enabled TC and DCC in milk products at low concentration levels (1 × 10-9 M and 1 × 10-7 M, respectively). Linear correlation between concentration and intensity was TC R2 = 0.96; DCD R2 = 0.99. The assignments of Raman bands of tetracycline and dicyandiamide consistent with density-functional-theory (DFT) calculations was made. The advantage of this transparent SERS substrate is that it is especially useful for measurement of analytes at the interface between Ag NP substrate layer and the opaque liquid containing the analytes without special pretreatment of the sample. Thus, this method may provide an alternative practical and reliable platform for rapid detection of contaminants in foods.