Visualization Detection of Melamine in the Protein Feed

Methane-oxidizing bacteria is the branches of methyl oxidation bacteria, It is a kind of gram-negative bacteria, which can directly use methane as carbon and energy sources. Methanobactin (Mb) is a fluorescent peptide released by the Methane oxidizing bacteria. It consists of two serine, glycine, two cysteine and methionine. Methanobactin (Mb) can coordinate Cu(I) by two hydroxyimidazolates, with one N and one S atom. Methanobactin (Mb) can also bind to Au(III) and reduce it to Au(0). In the presence of hydroquinone as a electron donator, Mb can catalyze Au(III) reduce to Au(0) and yield gold nanoparticles continuously. Surface plasmon resonance of gold nanoparticles makes its aqueous solution has a typical absorption peak between 500 and 600nm, and a unique color of that can be observed by naked eyes. It can be identified by the color change and used in the detection of certain substances. In this paper, visual detection of melamine in protein feed based on methanobactin-(Mb) induced gold nanoparticles formation was studied. Visual detection is convenient and quick. Different concentrations of melamine in protein feed have been detected. The interference of several kinds of ingredients in protein feed have been investigated. The detection limit and the recovery rate have been calculated, either. The detection limit of melamine is much lower than 1 ppm.