论文部分内容阅读
The detection for melamine has attracted much attention due to its toxicity to the kidney of animals and humans.Herein,we reported a magnetic relaxation switch (MRSw) assay for melamine with Fe/Fe3O4 nanoparticles functionalized by the dopamine conjugated with methoxypoly (ethylene glycol) carboxyl acid (mPEG-COOH) and (2,4,6-trioxo-1,3,5-triazin-1-yl) acetic acid (TTAA) (TTAA–Fe/Fe3O4 NPs).The approach of the MRSw assay for melamine is based on the aggregation of TTAA–Fe/Fe3O4 NPs induced by the special triple hydrogen bonds between melamine and TTAA,which results in the increase of the spin–spin relaxation time (T2) of surrounding water protons of nanoparticles.Due to no limitation of light scattering,the detection of melamine with the MRSw assay can be performed in a turbid medium without pre-treatment and purification.Upon addition of the different concentration of melamine to an aqueous solution of TTAA–Fe/Fe3O4 NPs ([Fe] = 32 M),the change of T2 value has a good linear relationship with the concentration of melamine below 16 M.The limit of detection (LOD) for melamine is ~2 M.Furthermore,the MRSw assay exhibits a high selectivity for melamine over cytosine,uracil and thymine with the similar structure.