Development of Gd3+-immobilized glutathione-coated magnetic nanoparticles for highly selective enrichment of phosphopeptides

In this study, we designed a gadolinium-based immobilized metal ion affinity chromatography material for the selective enrichment of phosphopeptides. Gadolinium ion was immobilized on the surface of glutathione-coated magnetic nanoparticles through a facile and effective synthetic route. The adsorbent integrated the advantages of superparamagnetism of Fe 3 O 4 core, good biological compatibility of glutathione , and strong interaction between gadolinium ion and phosphopeptides. It was employed to enrich phosphopeptides from standard protein digests coupled with MALDI-TOF MS. Results demonstrated that the adsorbent possessed high selectivity for phosphopeptides, good reusability and reproducibility. Moreover, the material provided selective enrichment of phosphopeptides from real samples including non-fat milk digests and human serum. The developed method exhibited high sensitivity (detection limit of 10 fmol), showing great potential in the detection of low-abundance phosphopeptides in biological samples.