Preparation Of Functional Copper Sulfide Composite Nanomaterials And Application In Enrichment Of Glycopeptide

Protein glycosylation refers to covalent additions glycosyl functional groups to proteins,which plays an important role in regulating the function of proteins and numerous cellular processes.Therefore,the study of the fine structure of glycosylated proteins,especially the glycosyl-modified peptides(glycopeptides),is of great significance for the early diagnosis of diseases and drug research.However,in a living organism,the native glycosylated proteins are usually present at substoichiometric levels,which creats a great challenge to mass-spectrometry analyses and identification.Over the past decade,a variety of selective affinity materials have been developed to capture trace amounts of glycopeptides from very complex biosamples.However,the highly complex biosamples and the increasingly sophisticated requirements of glycosylated proteins analysis require the continuous updating of new chromatographic materials.Therefore,it is pretty necessary to develop efficient glycopeptide enrichment materials for the study of protein glycosylation.In recent years,the nanocomposites have been widely used in separation and enrichment of glycoproteins/glycopeptides.Basing on the interaction between functional groups on the surface of nanoparticles and glycopeptides,the materials can enrich glycopeptides efficiently from the protein digests.In this paper,a kind of flower-like copper sulfide nanoparticles(CuS NPs)was prepared by solvothermal method.Because of its unique physicochemical properties,it can be used as an alkali-resistans inert substrate material.Inspired by the interaction model of multi hydrogen bonds between lectins and carbohydrates,we proved L-dopa can form strong hydrogen bond with sialic acid via NMR titration and QCM-D experiments.The L-dopa contains a catechol structure which can adhere tightly to the wet surfaces of various types of materials,and this adhesion is strong under physiological condition.We explored an optimal experimental condition to introduce functional groups such as amino groups and hydroxyl groups on the surface of CuS to develop a novel chromatography material.The structure,morphology and composition of the modified CuS were characterized by X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),Fourier transform infrared spectroscopy(FTIR),thermogravimetric analysis(TGA)and scanning electron microscopy(SEM).The results indicated that the L-dopa has been modified on the surface of CuS with high-density and provided lots of active groups without changing its crystal structure.Meanwhile,the density of the L-dopa on the surface of CuS NPs could be adjusted by regulating the reaction time.The chromatographic separation experiments indicated that,this materials DOPA@CuS displays high-performance enrichment capacity towards sialylated glycopeptides and 47 glycopeptides were found under 100-fold interference of bovine serum albumins digests via MS analysis.Compared with the Sepharose,more glycopeptide signals was found under a larger proportion of interfering proteins in the protein mixed solution.Meanwhile,this study developed a new nanoparticles for the separation and enrichment of glycoproteins.