title: One-step synthesis of silver/dopamine nanoparticles and visual detection of melamine in raw milk.
abstract: In this work, we propose a simple, sensitive and reliable assay for melamine in raw milk with dopamine-stabilized silver nanoparticles (AgNPs) as a colorimetric reader. Dopamine can reduce Ag(+) and functionalize the produced AgNPs to form monodispersed AgNPs. The coexisting melamine in reaction solution could bind dopamine through Michael addition and Schiff base reactions, which leads to the aggregation of AgNPs and induces a colorimetric response. The one-step assay is simple, rapid and highly sensitive. The color-change is quantitatively correlated with the concentration of melamine in the range of 10 ppb to 1.26 ppm, which is below the safety limit in China (1.0 ppm) and EU (2.0 ppm). The coexisting substances including phenylalanine, dl-leucine, l-glutamate, sulfanilic acid, Mg(2+), galactose, lysine, urea and glucose do not affect the determination of melamine. The colorimetric sensor can be used for rapid monitoring of raw milk quality.
authors.affiliation: State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing, 100085, China.
authors.forename: Yurong
authors.initials: Y
authors.lastname: Ma
authors.forename: Hongyun
authors.initials: H
authors.lastname: Niu
authors.forename: Xiaole
authors.initials: X
authors.lastname: Zhang
authors.forename: Yaqi
authors.initials: Y
authors.lastname: Cai
mesh_terms: D000818:Animals; D002417:Cattle; D003124:Colorimetry; D004298:Dopamine / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry*; D008892:Milk / Q000737:chemistry*; D012834:Silver / Q000737:chemistry*; D014227:Triazines / Q000032:analysis*
chemical_list: D014227:Triazines; D012834:Silver; C011907:melamine; D004298:Dopamine