Enrichment and Identification of Metallothionein by Functionalized Nano-Magnetic Particles and Matrix Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry

As a low molecular weight protein with the ability of binding metal ions and high inducibility, metallothionein (MT) is often regarded as an important biomarker for assessment of heavy metal pollution in water environment. In the light of that the traditional process of enrichment and identification is time-consuming and complicated, we prepared a core-shell nanoparticle, gold-coated iron oxide nanoparticles (Fe₃O₄@Au NPs) herein. It possessed the advantages of fast response to magnetic fields and optical properties attributing to Fe₃O₄ and Au nanoparticles, respectively. The Fe₃O₄@Au nanoparticles could be used to enrich MT simply through Au–S interaction, and the purified proteins were determined by matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF/MS). The results showed that the Fe₃O₄@Au nanoparticles could directly enrich MT from complex solutions and the detection limit could be as low as 10 fg mL^?1.