Synthesis of Polydopamine-Coated Magnetic Graphene for Cu²⁺ Immobilization and Application to the Enrichment of Low-Concentration Peptides for Mass Spectrometry Analysis

Abstract

In this work, Cu(2+)-immobilized magnetic graphene@polydopamine (magG@PDA@Cu(2+)) composites were synthesized for the first time. Magnetic graphene prepared via a hydrothermal reaction were easily encapsulated by a layer of polydopamine through the oxidative polymerization of dopamine in alkaline buffer, and it was conveniently modified with Cu(2+) ions afterward. The as-prepared magG@PDA@Cu(2+) composites were endowed with strong magnetic responsivness, excellent dispersibility and biological compatibility. We applied the novel nanocomposites to the enrichment and identification of low-concentration standard peptides, peptides in standard protein digestions, endogenous peptides in human urine and serum. The enriched peptides were eluted and analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The magG@PDA@Cu(2+) composites were proved to exhibit great affinity to both hydrophobic and hydrophilic peptides, thus providing a rapid and facile approach to the extraction of low-concentration peptides. Notably, peptides at an extremely low concentration of 10 pM could be detected by MALDI-TOF MS after enrichment with magG@PDA@Cu(2+) composites. The results demonstrated that the magG@PDA@Cu(2+) composite is a promising candidate for the enrichment of low-abundance peptides for mass spectrometry analysis.

Development of magnetic graphene @hydrophilic polydopamine for the enrichment and analysis of phthalates in environmental water samples

“…And the strong peak at 261 indicated the graphitic layers were observed simultaneously. The result was in accordance with the previous reports [33,34].…”

Facile Synthesis of Magnetic Mesoporous Hollow Carbon Microspheres for Rapid Capture of Low-Concentration Peptides

“…19,20 However, direct analysis of peptides extracted from biological samples by MS is a great challenge, owing to the low concentrations of the target peptides, strong interference, and suppression of high-abundance biomolecules as well as other impurities (e.g., salts and surfactants). A number of nanostructures for the capture and purification of low-concentration peptides, such as silanized silica microspheres, polymer reverse micelles, metal–organic frameworks, and hybrid materials, 21−25 have been explored to capture and purify the low-concentration peptides from biosamples. Although these materials have shown interesting performance, they are compromised by their complex fabrication strategies, limited affinity sites, poor stability, and poor recyclability.…”

Preparation of magnetic graphene @polydopamine @Zr-MOF material for the extraction and analysis of bisphenols in water samples

“…The strong peak at 26.5° was indicative of the graphitic layers. And the typical diffraction peaks around 30.0°, 35.4°, 43.1°, 53.5°, 57.2° and 62.6° were related to Fe 3 O 4 microspheres[37,38]. And the diffraction peaks at 16.7° and 18.3° could be indexed to Zr-MOFs[39].…”