| Proteomics has received a lot of attention in the biomedical field recently because it has the potential to reveal the state of various diseases.The identification of protein biomarkers is favorable for the precise detection of diseases and could achieve the early diagnosis and intervention of diseases,thus improving the survival rates.Because of its high sensitivity and ability to detect multiple substances at the same time,mass spectrometry has been designated as the core technology for proteomics research.However,on account of the wide dynamic range and complexity of real biological samples,the signal of low-abundance peptides may be severely suppressed and difficult to detect in mass spectrometry.Of note,the pre-enrichment of the low-abundance peptide before detection is a powerful strategy to address the aforementioned issues.Thus,this thesis presented two nanomaterials that could be employed for low-abundance peptide enrichment,and their enrichment performance was studied by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry（MALDI-TOF MS）.This thesis is divided into three sections:The first part of the thesis mainly reviews and summarizes the enrichment methods of low-abundance peptides and functional peptides（glycopeptides and phosphopeptides）.We first introduced the significance and main challenges of proteomics and then summarized the reported enrichment methods and typical enrichment nanomaterials for low-abundance peptides and functional peptides with diverse structural properties.Finally,the purpose and major content of this thesis were explained.In the second part of this thesis,we developed a novel nanomaterial for the enrichment of low-abundance peptides.The third-generation dendrimer with the surface functionalization of amino and carboxyl groups was obtained by the solid-phase peptide synthesis strategy with alkenyl modification of its central sites.And the mercapto-modified mesoporous silica nanomaterial SBA-15 was developed.Then the nanocomposites（called SBA-15/G3-NH2 and SBA-15/G3-COOH）were formed by the thiol-ene click reaction of dendrimers and mesoporous silica nanomaterials.A series of characterization results revealed that the formed nanocomposites,which combined the merits of dendrimers and mesoporous silica nanomaterial SBA-15,demonstrated good hydrophobicity and size exclusion effects,allowing for enhanced adsorption and enrichment of low-abundance peptides.The study further evaluated the enrichment performance of the nanocomposites by using standard protein digests and real biological samples,both of which showed good enrichment capability for low-abundance peptides.This work explores the application prospects of dendrimer-based nanocomposites in low-abundance peptide enrichment for the first time and offers a new idea for the development of novel enrichment materials.In the third part,we developed amorphous iron-based metal-organic frameworks（MOFs）for the simultaneous enrichment of glycopeptides and phosphopeptides.First,we synthesized MIL-88B（cMIL-88B）with high crystallinity as the support and etched cMIL-88B with dimethylimidazole solution to get amorphous MIL-88B（aMIL-88B）.The iron ions in the resulting aMIL-88B can effectively enrich phosphopeptides through chelation reaction.In the meantime,the amorphization strategy can increase the hydroxy group on the surface of the material,enhance its hydrophilicity and facilitate the enrichment of glycopeptides.Furthermore,it could increase the specific surface area of the nanomaterial as well as improve the adsorption of functional peptides.The enrichment capability for glycopeptides and phosphopeptides was evaluated.And the results showed that aMIL-88B revealed better performance for the simultaneous enrichment of glycopeptides and phosphopeptides compared with cMIL-88B.This study investigates the structure-effect relationship between amorphous strategy and peptide enrichment performance,providing a new point for developing novel MOF materials for functional peptide enrichment. |
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