Synthesis of C8-Functionalized Magnetic Graphene with a Polydopamine Coating for the Enrichment of Low-Abundance Peptides

Magnetic mesoporous carbon nanocomposites derived from bimetallic metal-organic frameworks for enrichment of low-abundance peptides

Mesopore-structured cobalt and nickel metal-organic frameworks (Co/Ni-ZIF) were synthesized by a self-assembly method using Co and Ni as bimetallic centers and 2-methylimidazole as the organic ligand at room temperature. The resulting rhombic dodecahedral nanocomposites possessing rich mesopores with an average diameter of 4 nm were collected centrifugally and then carbonized under a nitrogen atmosphere to generate bimetallic magnetic porous carbon nanocomposites (Co/Ni-MCNs). After thorough characterization, the as-prepared Co/Ni-MCNs decorated with a graphite shell layer with pyridinic nitrogen were utilized in magnetic separation and enrichment of low-abundance peptides through hydrophobic and π-π stacking interactions. This is the first attempt to prepare mesoporous carbon materials having plentiful holes with bimetal MOFs as precursors, in which partial nickel-containing components served as sacrificial templates. Owing to the ordered structure, abundant mesopores, rich interaction sites, excellent magnetic properties and good compatibility with biological tissues, this proposed magnetic affinity probe has been successfully used in the identification of endogenous peptides in human urine and serum in combination with matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS).

A novel carbon-based material with titanium and zirconium ions etched on hollow mesoporous carbon tubes for specific capture of phosphopeptides and exosomes

The analysis of low abundance phosphopeptides in organisms and specific capture exosomes are crucial for unraveling the pathogenesis of diseases. For this reason, titanium-zirconium ions and highly biocompatible dopamine and polyimide tubes (PITs) were introduced, and a novel carbon-based material with titanium and zirconium ions etched on hollow mesoporous carbon tubes (HMCT), denoted as G@C@Ti-Zr-HMCT, comes into being after high-temperature calcination. Attributing to the tightly bound titanium and zirconium ions to HMCT and the high carbon content of the polydopamine carbonaceous layer, G@C@Ti-Zr-HMCT displays satisfactory capability of enriching phosphopeptides with satisfactory detection limit (0.2 fmol), extraordinary selectivity (1:2000), and good loading capacity (100 μg/mg). In addition, 25 phosphopeptides related to 25 phosphoproteins from the serum of Parkinson's disease (PD) patients and 30 phosphopeptides attributed to 26 phosphoproteins from the serum of healthy individuals were enriched by G@C@Ti-Zr-HMCT, respectively. In addition, bioinformatics analysis of the above results revealed that PD were associated with serine, threonine, and leucine of high frequency, blood coagulation in BP, Golgi apparatus and mitochondrial outer membrane in CC, and heparin binding in MF. Moreover, the phospholipid bilayer of exosomes and metallic titanium and zirconium ions interact to produce the following results: this highly biocompatible carbon-based material was successfully applied to capture exosomes, which offers a promising platform for isolating exosomes. To sum up, these delightful results confirmed without doubt that G@C@Ti-Zr-HMCT has enjoyed a splendiferous future in the specific capture of phosphopeptides and exosomes isolation.

The synthesis of Zr-metal-organic framework functionalized magnetic graphene nanocomposites as an adsorbent for fast determination of multi-pesticide residues in tobacco samples

In this paper, a simple and reliable method has been established to determine the residues of nine pesticides in tobacco by using GC-MS coupled with magnetic solid phase extraction. A novel magnetic Zr-MOF nanocomposite based on graphene was synthesized, and characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FT-IR), Raman spectroscopy and N2 adsorption-desorption measurements. The prepared material has the advantage of large surface area (178 m2/g), good magnetic response and high thermal stability, which is shown to be suited for the fast enrichment of multi-pesticides in tobacco matrix. The extraction conditions including amount of adsorbent, adsorption time, eluting solvent as well as desorption time were investigated. The whole process of pretreatment is accomplished within 10 min. This method shows low limit of detection, wide linear range and good reproducibility (relative standard deviations <12.7%), satisfactory recoveries were obtained, ranging from 57.9% to 126.3% for tobacco samples.

Graphene/graphene oxide and their derivatives in the separation/isolation and preconcentration of protein species: A review

The distinctive/unique electrical, chemical and optical properties make graphene/graphene oxide-based materials popular in the field of analytical chemistry. Its large surface offers excellent capacity to anchor target analyte, making it an powerful sorbent in the adsorption and preconcentration of trace level analyte of interest in the field of sample preparation. The large delocalized π-electron system of graphene framework provides strong affinity to species containing aromatic rings, such as proteins, and the abundant active sites on its surface offers the chance to modulate adsorption tendency towards specific protein via functional modification/decoration. This review provides an overview of the current research on graphene/graphene oxide-based materials as attractive and powerful adsorption media in the separation/isolation and preconcentration of protein species from biological sample matrixes. These practices are aiming at providing protein sample of high purity for further investigations and applications, or to achieve certain extent of enrichment prior to quantitative assay. In addition, the challenges and future perspectives in the related research fields have been discussed.

Bioinspired preparation of monolithic ordered mesoporous silica for enrichment of endogenous peptides

Monolithic ordered mesoporous silica with various sizes and shapes were prepared in one-pot modified Stöber synthesis using pomelo peel and CTAB as dual templates, and applied as packing adsorbents for peptide enrichment.

Facile synthesis of hydrophilic magnetic graphene@metal–organic framework for highly selective enrichment of phosphopeptides

A hydrophilic magnetic graphene@metal–organic framework (MOF) was designed and synthesized for highly selective enrichment of phosphopeptides.

Synthesis of a highly dispersive sinapinic acid@graphene oxide (SA@GO) and its applications as a novel surface assisted laser desorption/ionization mass spectrometry for proteomics and pathogenic bacteria biosensing

GO-modified sinapinic acid was synthesized and characterized; it was then investigated for use in SALDI-MS for proteomics and pathogenic bacterial biosensing.

Rational synthesis of novel recyclable Fe3O4@MOF nanocomposites for enzymatic digestion

Magnetic MOFs were synthesized for enzyme immobilization. The magnetic MOF–trypsin exhibited significantly improved digestion performance for different kinds of enzymes.