Preparation Of Magnetic Carbon Nirtide Composite And Its Application In Phosphopeptides Enrichment

Protein phosphorylation is an important post-translational modification that plays an important role in complex biological processes,has already obtained a widespread application in enrichment field.Mass spectrometry（MS）is most commom methods in phosphoproteomics research,however,the phosphopeptides was dynamic and have a large number of interference from non-phosphopeptides,resulting in the reduction of the detection sensitivity of mass spectrometry.Therefore,enrichment and isolation are crucial prior to MS analysis for phosphopeptides enrichment.At present,affinity materials based on various enrichment mechanisms have been designed and synthesized for the separation and detection of phosphopeptides.This paper based on metal oxide affinity chromatography（MOAC）,fixed metal ion affinity chromatography（IMAC）and ion exchange chromatography（AEX）,a series of magnetic carbon nitride（g-C₃N₄）composites materials were prepared and the phosphopeptides in biological samples were detected by mass spectrometry.The detailed contents were divided into the following three parts:1.The two-dimensional g-C₃N₄ nanosheets were prepared by thermal polymerization reaction and peeling using melamine as the precursor,and magnetic g-C₃N₄ nanomaterials were prepared by co-precipitation.The molybdenum trioxide was introduced to obtain the final adsorption material（Fe₃O₄/g-C₃N₄/Mo O₃）.The material has good magnetic properties and abundant contact sites.Combined with the detection of MALDI-TOF MS and Nano LC-MS system offered high selectively for phosphopeptides from biological samples such as non-milk and human serum.In addition,this method has high recovery rate（91.3%）and good repeatability.2.The magnetic g-C₃N₄ nanocomposites(Fe₃O₄/Pg-C₃N₄-Ti⁴⁺)modified by titanium ions were synthesized through coprecipitation and electrostatic adsorption for the separation and enrichment of low abundance phosphopeptides in biological samples.Based on the enrichment mechanism of IMAC and AEX,the composite material had specific affinity for phosphopeptides.Through the characterization of VSM and Zeta and the detection of adsorption performance by p NPP,the material has the advantages of positive electricity,high adsorption capacity and fast magnetic response.In combination with MALDI-TOF MS detection,the material has a detection limit as low as 0.02 fmol.3.The 2D layered material of magnetic g-C₃N₄ was prepared by co-precipitation method,L-Alanyl-L-Glutamine（L-Ala-L-Gln）was combined with magnetic g-C₃N₄by dehydration condensation,and cerium ion was modified on the surface of magnetic nanoparticles to prepare magnetic g-C₃N₄ nanocomposites(Fe₃O₄/g-C₃N₄-L-Ala-L-Gln-Ce⁴⁺).The materials were characterized using characterization methods such as VSM and TG,The material has superparamagnetism,large electromobility and stability.The method gave inspirations of using 2D materials in the field of separation and enrichment of complex biological.