Robust Dual-Biomimetic Titanium Dioxide-Cellulose Monolith for Enrichment of Phosphopeptides

Abstract

Metal oxide affinity chromatography (MOAC) is considered to be one of the most effective methods for phosphopeptide enrichment. However, most of the materials used in the method are powder; frequent centrifugation is necessitated during the enrichment process, and potential risks of loss of peptides and materials and clogging of the column employed for liquid chromatography–mass spectrometry (LC–MS) arise. Moreover, the reusability of these materials to achieve sustainability was hardly investigated. To overcome these limitations, herein, inorganic titanium dioxide (TiO2) was coated onto the skeletal surface of the organic cellulose monolith (CM) material with a coral-like structure via a sol–gel method. This produced an organic–inorganic hybrid TiO2-CM material, which contained a combination of organic and inorganic substances, making it mimic the mollusk shell in terms of composition. The prepared TiO2-CM material as monolith exhibited excellent mechanical strength and did not break during the enrichment process; thus, the tedious implementation of multiple centrifugation cycles was prevented, thereby streamlining the experimental procedure and avoiding the loss of peptides and materials. Moreover, a large amount of TiO2 was introduced onto the surface of the CM material, and thus, the resultant TiO2-CM material exhibited a large surface area. As a result, the fabricated TiO2-CM material was successfully applied to the enrichment of phosphopeptides obtained from the tryptic digests of a BSA/β-casein (mass ratio, 500/1) mixture. The results were superior to those achieved for commercial TiO2 beads, confirming that TiO2-CM has excellent selectivity for phosphopeptides and reusability. Furthermore, 9287 unique phosphopeptides derived from the 2661 phosphoproteins were successfully identified from two milligrams of tryptic digests of Hela cell exosomes obtained through five independent replications after enriching using the TiO2-CM material. The results indicated that the material has good application prospects in the analysis of protein phosphorylation. Furthermore, TiO2-CM consists of green and cheap cellulose as the skeleton, and its synthesis process is environment-friendly, simple, and inexpensive.

Enrichment of Phosphopeptides Based on Zirconium Phthalocyanine-Modified Magnetic Nanoparticles

“…1,2 Protein phosphorylation, as one of the most essential of PTMs, performs important functions in numerous biological events. 3,4 Protein phosphorylation is a highly complex and dynamic process. Abnormal phosphorylation regulation is related to a variety of human diseases, such as leukemia, neurodegenerative diseases, etc.…”

Functionalized cellulose monolith based affinity chromatography columns for efficient separation of protein molecules

“…2 MPa in the dry state and 0.1 MPa in the wet state, at 20% compression). 38,39 The monoliths can be transformed into efficient affinity chromatography columns for selective adsorption of proteins by immobilization of suitable ligands over the porous surface. 40 Various strategies are adopted to improve the performance of protein adsorption like ligand modification, 41 orientation fixation, 42 increasing the surface area by loading nanoparticles, 43 etc.…”

“…220 °C. 38 Moreover, the rigid structure of cellulose provides excellent mechanical stability to the monoliths both in dry and wet states, contributing to the high durability required for flow systems (compression stress is ca. 2 MPa in the dry state and 0.1 MPa in the wet state, at 20% compression).…”

Shape-Stabilized Monolithic Composite for Switchable Stiffness Based on Cellulose and Poly(stearyl methacrylate)

“…Also, the skeletal backbone of CM composed of amorphous cellulose has high porosity, allowing great permeability of substances into the backbone as well as pores of CM. These favorable properties have led to the application of the CM in catalysis, ion exchange, adsorption, and chromatography . Moreover, because of its porous nature, the CM can absorb solvents, which enables effective functionalization not only on the surface but also on the backbone in the interior.…”

“…These favorable properties have led to the application of the CM in catalysis, 27 ion exchange, 28 adsorption, 29 and chromatography. 30 Moreover, because of its porous nature, the CM can absorb solvents, which enables effective functionalization not only on the surface but also on the backbone in the interior. Therefore, the functionalized responsive components of SCMs in the CM are expected to be densely packed, thereby conferring excellent mechanical robustness.…”