Facile synthesis of titanium(IV) ion-immobilized poly-glycidyl methacrylate microparticles functionalized with polyethylenimine and adenosine triphosphate for highly specific enrichment of intact phosphoproteins

Recent advances in development of functional magnetic adsorbents for selective separation of proteins/peptides

Nowadays, proteins separation has attracted great attention in proteomics research. Because the proteins separation is helpful for making an early diagnosis of many diseases. Magnetic nanoparticles are an interesting and useful functional material, and have attracted extensive research interest during the past decades. Because of the excellent properties such as easy surface functionalization, tunable biocompatibility, high saturation magnetization etc, magnetic microspheres have been widely used in isolation of proteins/peptides. Notably, with the rapid development of surface decoration strategies, more and more functional magnetic adsorbents have been designed and fabricated to meet the growing demands of biological separation. In this review, we have collected recent information about magnetic adsorbents applications in selective separation of proteins/peptides. Furthermore, we present a comprehensive prospects and challenges in the field of protein separation relying on magnetic nanoparticles.

Advances in proteomics sample preparation and enrichment for phosphorylation and glycosylation analysis

As the common and significant chemical modifications, post-translational modifications (PTMs) play a key role in the functional proteome. Affected by the signal interference, low concentration, and insufficient ionization efficiency of impurities, the direct detection of PTMs by mass spectrometry (MS) still faces many challenges. Therefore, sample preparation and enrichment are an indispensable link before MS analysis of PTMs in proteomics. The rapid development of functionalized materials with diverse morphologies and compositions provides an avenue for sample preparation and enrichment for PTMs analysis. In this review, we summarize recent advances in the application of novel functionalized materials in sample preparation for phosphoproteomes and glycoproteomes analysis. In addition, this review specifically discusses the design and preparation of functionalized materials based on different enrichment mechanisms, and proposes research directions and potential challenges for proteomic PTMs research.

Novel Ti4+-Chelated Polyoxometalate/Polydopamine Composite Microspheres for Highly Selective Isolation and Enrichment of Phosphoproteins

Selective isolation and enrichment of phosphoproteins play critical roles for identification of biomarkers in biological applications. Herein, a kind of polyoxometalate (P₅W₃₀)/polydopamine (PDA) composite microspheres is readily synthesized via an in situ polymerization way, followed by immobilization of Ti⁴⁺ on the surface of the microspheres to obtain P₅W₃₀/PDA-Ti⁴⁺. Due to metal affinity and π stacking interaction, this novel material exhibits high selectivity to β-casein (β-ca), and the theoretical maximum adsorption capacity is as high as 1250 mg g^-1, fitting well with the Langmuir model. The captured β-ca can be collected by using Britton-Robinson (B-R) buffer at pH 7.0, and a recovery of 81.5% is acquired. The enrichment factor is over 150 at a mass ratio of BSA/β-ca = 100:1, indicating that phosphoproteins can be purified by P₅W₃₀/PDA-Ti⁴⁺. Moreover, the application of P₅W₃₀/PDA-Ti⁴⁺ as sorbent in real biological samples has been investigated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis, and the consequences show that this kind of material is able to selectively isolate phosphoproteins from complex samples such as drinking milk and chicken egg white.

Smart polymers driven by multiple and tunable hydrogen bonds for intact phosphoprotein enrichment

Separation of phosphoproteins is essential for understanding their vital roles in biological processes and pathology. Transition metal-based receptors and antibodies, the routinely used materials for phosphoproteins enrichment, both suffer from low sensitivity, low recovery and coverage. In this work, a novel smart copolymer material was synthesized by modifying porous silica gel with a poly[(N-isopropylacrylamide-co-4-(3-acryloylthioureido) benzoic acid)0.35] (denoted as NIPAAm-co-ATBA0.35@SiO2). Driven by the hydrogen bonds complexation of ATBA monomers with phosphate groups, the copolymer-modified surface exhibited a remarkable adsorption toward native α-casein (a model phosphoprotein), accompanied with significant changes in surface viscoelasticity and roughness. Moreover, this adsorption was tunable and critically dependent on the polarity of carrier solvent. Benefiting from these features, selective enrichment of phosphoprotein was obtained using NIPAAm-co-ATBA0.35@SiO2 under a dispersive solid-phase extraction (dSPE) mode. This result displays a good potential of smart polymeric materials in phosphoprotein enrichment, which may facilitate top-down phosphoproteomics studies.