title: Synthesis of polydopamine-coated magnetic graphene for Cu(2+) 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.
authors.affiliation: Department of Chemistry and Institutes of Biomedical Sciences, Fudan University , Shanghai 200433, China.
authors.forename: Man
authors.initials: M
authors.lastname: Zhao
authors.forename: Chunhui
authors.initials: C
authors.lastname: Deng
authors.forename: Xiangmin
authors.initials: X
authors.lastname: Zhang
mesh_terms: D003300:Copper / Q000737:chemistry*; D006108:Graphite / Q000138:chemical synthesis* / Q000737:chemistry; D006801:Humans; D007211:Indoles / Q000138:chemical synthesis* / Q000737:chemistry; D008280:Magnetics; D013058:Mass Spectrometry; D010455:Peptides / Q000737:chemistry; D011108:Polymers / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D007211:Indoles; D010455:Peptides; D011108:Polymers; C568283:polydopamine; D006108:Graphite; D003300:Copper