Specific enrichment of phosphopeptides by using magnetic nanocomposites of type Fe3O4@graphene oxide and Fe3O4@C coated with self-assembled oligopeptides


Iron(III-immobilized magnetic nano-composites (MNCs) were first fabricated using one-step aqueous self-assembly of oligopeptides (Glu-Pro-Ala-Lys-Ala-Lys-Ala-Lys; EPAK-VI) for the highly selective capture of phosphopeptides from complex biological samples. Under physiological conditions, EPAK-VI can readily self-organize into a robust and complete coating layer mainly composed of β-sheets and β-turns on the surface of Fe3O4@GO and Fe3O4@C MNCs. Tailored by the cyclic structure of proline, the Glu-Pro motifs of EPAK-VI are vertically erected on the surface and thus serve as an effective linker to chelate Fe3+ through carboxyl (COO-) group in the glutamic acid (E) residues. The ionic hydrogen bonds between the ε-amino groups and the surface negative charges coupled with intermolecular hydrogen bonds render the EPAK-VI coating on the MNCs insusceptible to repeated extreme washing conditions. The Fe3+-EPAK-VI coated MNCs exhibit high enrichment efficiency for β-casein tryptic digest (0.05 fmol μL−1), excellent selectivity from mixed digests (β-casein/bovine serum albumin, mass ratio 1:500), and high recovery rate (over 80%).

Schematic representation of the fabrication of Fe3+-immobilized MNCs for phosphopeptide enrichment.

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immobilized metal ion affinity chromatography


magnetic nano-composites


magnetic nanoparticles




graphene oxide


mass spectrometry




metal organic framework


bovine serum albumin






acetic acid




ethylene glycol


sodium acetate




transmission electron microscopy


X-ray photoelectron


attenuated total reflection Fourier-transform infrared


vibrating-sample magnetometry


water contact angle


matrix-assisted laser desorption/ionization time-of-flight




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This work was supported by the National Natural Science Foundation of China (No. 21175088) and the Fundamental Research Funds for the Central Universities (GK201801006).

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Correspondence to Fuquan Dang.

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Li, N., Zhang, L., Shi, H. et al. Specific enrichment of phosphopeptides by using magnetic nanocomposites of type Fe3O4@graphene oxide and Fe3O4@C coated with self-assembled oligopeptides. Microchim Acta 187, 144 (2020). https://doi.org/10.1007/s00604-019-4096-z

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  • Nanocomposite
  • Self-assembly
  • Oligopeptide
  • Enrichment
  • Phosphopeptide