Ti4+ functionalized β-cyclodextrin covalent organic framework as a new immobilized metal ion affinity chromatography platform for selective capture of phosphorylated peptides and exosomes

Preparation of a titanium-functionalized polymeric material rich in hydrophilic groups for phosphoproteome and glycoproteome analyses in serum

The analysis of protein phosphorylation and glycosylation is critical for investigating disease development. In this work, 1,2-epoxy-5-hexene and N,N-methylenebisacrylamide were polymerized with vinyl phosphate to produce a polymer (denoted as PVME), which contained a variety of hydrophilic groups. The material's hydrophilicity was further enhanced by a ring-opening reaction with cysteine (the product was denoted as Cys-PVEM). Finally, titanium sulfate was combined with Cys-PVME to form titanium-rich polymers (Cys-PVME-Ti4+) for the enrichment of phosphopeptides and glycopeptides. Cys-PVME-Ti4+ has a good sensitivity (0.02 fmol) and selectivity (1 : 1000) with a loading capacity of 62 mg g-1, recyclability (9 cycles), and a good recovery rate (101.6 ± 0.60%) for phosphopeptides, and good sensitivity (0.01 fmol μL-1), selectivity (1 : 2000), a loading capacity of 62.5 mg g-1, recyclability (9 cycles), and a good recovery rate (98.7 ± 1.2%) for glycopeptides. In addition, after enrichment with this material, 27 phosphopeptides with 14 phosphoproteins and 223 glycopeptides associated with 88 glycoproteins were captured from the serum of colorectal cancer patients, while 27 phosphopeptides associated with 14 phosphoproteins and 210 glycopeptides associated with 111 glycoproteins were also captured from the serum of a normal control. Gene ontology (GO) analysis revealed that complement activation, extracellular region, extracellular space, blood coagulation, the IgG immunoglobulin complex, and heparin binding were different between normal control and colorectal cancer, implying that related pathways are likely involved in colorectal cancer pathogenesis.

Facile preparation of titanium functionalized cross-linked chitosan polymer for phosphoproteome analysis in serum

Efficient phosphopeptide enrichment is extremely important for proteomics research. In this work, chitosan (CTs), 2,3-dihydroxyterephthalaldehyde (2,3-DHA), and carbohydrazide (CHZ) are polymerized to generate the polymer (DHA-CTs-CHZ), and then the polymer (DHA-CTs-CHZ) is coupled with a significant number of titanium ions to enrich phosphopeptides. The material exhibits high selectivity (5000:1 M ratio of BSA to β-casein), sensitivity (0.001 fmol/μL), loading (83.3 μg/mg), recovery (98.6 ± 1.2 %), and effective size exclusion for phosphopeptide enrichment. In addition, 46 phosphopeptides and 31 phosphorylated sites associated with 27 phosphorylated proteins were successfully captured from the serum of normal subjects, while 47 phosphopeptides and 35 phosphorylated sites associated with 30 phosphorylated proteins were successfully captured from Alzheimer's disease (AD) patients' serum.

Exploitation of porphyrin-based titanium-rich porous organic polymers for targeted phosphopeptide enrichment from the serum of colorectal cancer individuals

A porphyrin-based titanium-rich porous organic polymer (Th-PPOPs@Ti4+) was designed based on immobilized metal ion affinity chromatography technique and successfully applied to phosphopeptide enrichment with 5,10,15,20-tetrakis(4-carboxyphenyl) porphine tetramethyl ester (TCPTE), 2,3-dihydroxyterephthalaldehyde (DHTA), and 2,3,4-trihydroxybenzaldehyde (THBA) as raw materials. Th-PPOPs@Ti4+ exhibited remarkable sensitivity (0.5 fmol), high selectivity (β-casein: BSA = 1:2000, molar ratio), outstanding recovery (95.0 ± 1.9%), reusability (10 times), and superior loading capacity (143 mg·g-1). In addition, Th-PPOPs@Ti4+ exhibited excellent ability to specifically capture phosphopeptides from the serum of colorectal cancer (CRC) individuals and normal subjects. Sixty phosphopeptides assigned to 35 phosphoproteins were obtained from the serum of CRC individuals, and 43 phosphopeptides allocated to 28 phosphoproteins were extracted in the serum of healthy individuals via nano-LC-MS/MS. Gene ontology assays revealed that the detected phosphoproteins may be inextricably tied to CRC-associated events, including response to estrogen, inflammatory response, and heparin binding, suggesting that it is possible that these correlative pathways may be implicated in the pathogenesis of CRC.

An amino-rich polymer-coated magnetic nanomaterial for ultra-rapid separation of phosphorylated peptides in the serum of Parkinson's disease patients

The elucidation of disease pathogenesis can be achieved by analyzing the low-abundance phosphopeptides in organisms. Herein, we developed a novel and easy-to-prepare polymer-coated nanomaterial. By improving the hydrophilicity and spatial conformation of the material, we effectively enhanced the adsorption of phosphopeptides and demonstrated excellent enrichment properties. The material was able to successfully enrich the phosphopeptides in only 1 min. Meanwhile, the material has high selectivity (1:2000), good loading capacity (100 μg/mg), excellent sensitivity (0.5 fmol), and great acid and alkali resistance. In addition, the material was applied to real samples, and 70 phosphopeptides were enriched from the serum of Parkinson's disease (PD) patients and 67 phosphopeptides were enriched from the serum of normal controls. Sequences Logo showed that PD is probably associated with threonine, glutamate, serine, and glutamine. Finally, gene ontology (GO) analysis was performed on phosphopeptides enriched in PD patients' serum. The results showed that PD patients expressed abnormal expression of the cholesterol metabolic process and cell-matrix adhesion in the biological process (BP), endoplasmic reticulum and lipoprotein in the cellular component (CC), and heparin-binding, lipid-binding, and receptor-binding in the molecular function (MF) as compared with normal individuals. All the experiments indicate that the nanomaterials have great potential in proteomics studies.