Yan-Lin Liu

Synthesis of novel Fe3O4@SiO2@CeO2 microspheres with mesoporous shell for phosphopeptide capturing and labeling

Fe(3)O(4)@SiO(2)@CeO(2) microspheres with magnetic core and mesoporous shell were synthesized, and the multifunctional materials were utilized to capture phosphopeptides and catalyze the dephosphorylation simultaneously, thereby labeling the phosphopeptides for rapid identification.

Synthesis and characteristic of the Fe3O4@SiO2@Eu(DBM)3·2H2O/SiO2 luminomagnetic microspheres with core-shell structure

The core-shell structured luminomagnetic microsphere composed of a Fe(3)O(4) magnetic core and a continuous SiO(2) nanoshell doped with Eu(DBM)(3).2H(2)O fluorescent molecules was fabricated by a modified Stöber method combined with a layer-by-layer assembly technique. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), confocal microscopy, photoluminescence (PL), and superconducting quantum interface device (SQUID) were employed to characterize the Fe(3)O(4)@SiO(2)@Eu(DBM)(3).2H(2)O/SiO(2) microspheres. The experimental results show that the microshpere has a typical diameter of ca. 500 nm consisting of the magnetic core with about 340 nm in diameter and silica shell doped with europium complex with an average thickness of about 80 nm. It possesses magnetism with a saturation magnetization of 25.84 emu/g and negligible coercivity and remanence at room temperature and exhibits strong red emission peak originating from electric-dipole transition (5)D(0)-->(7)F(2) (611 nm) of Eu(3+) ions. The luminomagnetic microspheres can be uptaken by HeLa cells and there is no adverse cell reaction. These results suggest that the luminomagnetic microspheres with magnetic resonance response and fluorescence probe property may be useful in biomedical imaging and diagnostic applications.

The GO/rGO–Fe3O4 composites with good water-dispersibility and fast magnetic response for effective immobilization and enrichment of biomolecules

The graphene oxide (GO)–Fe3O4 and the reduced graphene oxide (rGO)–Fe3O4 composites with good water dispersibility, high affinity and rapid magnetic response have been prepared via a facile grafting method. They can be used for the effective immobilization of proteins and the enrichment of peptides, respectively. By taking advantage of the high loading capacity and the abundant hydrophilic groups of the GO–Fe3O4 composites, they can be applied to immobilize proteins. The amount of loading of protein (BSA) on GO–Fe3O4 is as high as 294.54 mg g−1. The rGO–Fe3O4 composites can be used to enrich the low-concentration peptides conveniently due to their high surface areas, special structures and strong magnetism. Nineteen target peptides with the sequence coverage of 21% can be enriched and detected from the highly diluted digest of BSA (5 fmol μL−1). These results reveal that the prepared GO/rGO–Fe3O4 composites have potential application as a carrier for biomolecule immobilization, enrichment, and separation.

Monodisperse REPO4 (RE=Yb, Gd, Y) Hollow Microspheres Covered with Nanothorns as Affinity Probes for Selectively Capturing and Labeling Phosphopeptides

Rare-earth phosphate microspheres with unique structures were developed as affinity probes for the selective capture and tagging of phosphopeptides. Prickly REPO(4) (RE = Yb, Gd, Y) monodisperse microspheres, that have hollow structures, low densities, high specific surface areas, and large adsorptive capacities were prepared by an ion-exchange method. The elemental compositions and crystal structures of these affinity probes were confirmed by energy-dispersive spectroscopy (EDS), powder X-ray diffraction (XRD), and Fourier-transform infrared (FTIR) spectroscopy. The morphologies of these compounds were investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and nitrogen-adsorption isotherms. The potential ability of these microspheres for selectively capturing and labeling target biological molecules was evaluated by using protein-digestion analysis and a real sample as well as by comparison with the widely used TiO(2) affinity microspheres. These results show that these porous rare-earth phosphate microspheres are highly promising probes for the rapid purification and recognition of phosphopeptides.

Fabrication of Novel Hierarchical Structured Fe3O4@LnPO4 (Ln=Eu, Tb, Er) Multifunctional Microspheres for Capturing and Labeling Phosphopeptides

Novel core-shell structured Fe3O4@LnPO4 (Ln=Eu, Tb, Er) multifunctional microspheres with a magnetic Fe3O4 core and a LnPO4 shell covered with spikes are synthesized for the first time through the combination of a homogeneous precipitation approach and an ion-exchange process. Their potential for selective capture, rapid separation, and easy mass spectrometry (MS) labeling of the phosphopeptides from complex proteolytic digests are evaluated. These affinity microspheres can improve the specificity for capture of the phosphopeptides, realize fast magnetic separation, enhance the MS detection signals, and directly identify phosphopeptides through 80 Da mass loss in the mass spectra. The synthesis strategy could become a general and effective technique for similar core-shell hierarchical structures.

A graphene-based multifunctional affinity probe for selective capture and sequential identification of different biomarkers from biosamples

A novel multifunctional graphene-based affinity probe has been explored for selective capture of two different types of peptides from the biosamples for sequential detection.

Novel core-shell Cerium(IV)-immobilized magnetic polymeric microspheres for selective enrichment and rapid separation of phosphopeptides

In this work, novel magnetic polymeric core-shell structured microspheres with immobilized Ce(IV), Fe3O4@SiO2@PVPA-Ce(IV), were designed rationally and synthesized successfully via a facile route for the first time. Magnetic Fe3O4@SiO2 microspheres were first prepared by directly coating a thin layer of silica onto Fe3O4 magnetic particles using a sol-gel method, a poly(vinylphosphonic acid) (PVPA) shell was then coated on the Fe3O4@SiO2 microspheres to form Fe3O4@SiO2@PVPA microspheres through a radical polymerization reaction, and finally Ce(IV) ions were robustly immobilized onto the Fe3O4@SiO2@PVPA microspheres through strong chelation between Ce(IV) ions and phosphate moieties in the PVPA. The applicability of the Fe3O4@SiO2@PVPA-Ce(IV) microspheres for selective enrichment and rapid separation of phosphopeptides from proteolytic digests of standard and real protein samples was investigated. The results demonstrated that the core-shell structured Fe3O4@SiO2@PVPA-Ce(IV) microspheres with abundant Ce(IV) affinity sites and excellent magnetic responsiveness can effectively purify phosphopeptides from complex biosamples for MS detection taking advantage of the rapid magnetic separation and the selective affinity between Ce(IV) ions and phosphate moieties of the phosphopeptides. Furthermore, they can be effectively recycled and show good reusability, and have better performance than commercial TiO2 beads and homemade Fe3O4@PMAA-Ce(IV) microspheres. Thus the Fe3O4@SiO2@PVPA-Ce(IV) microspheres can benefit greatly the mass spectrometric qualitative analysis of phosphopeptides in phosphoproteome research.

Magnetic γ-Fe2O3@REVO4 (RE = Sm, Dy, Ho) affinity microspheres for selective capture, fast separation and easy identification of phosphopeptides

The multifunctional microspheres consisting of the magnetic γ-Fe2O3 core and the affinity REVO4 (RE = Sm, Dy, Ho) shell have been synthesized via the homogenous precipitation-calcination-ion exchange three-step synthetic route. Their morphologies, structures, surface properties, and magnetisms were characterized, respectively. SEM and TEM images indicate that they all have an average size of about 400 nm and very rough surfaces. The TEM images further reveal that the γ-Fe2O3@REVO4 microspheres are all core-shell structures and the REVO4 shells are about 55-60 nm in thickness. The XRD pattern analyses show that the magnetic γ-Fe2O3 cores belong to cubic structure and the REVO4 (RE = Sm, Dy, Ho) shells are composed of their corresponding tetragonal major phases. HRTEM images, FTIR spectra and EDS further demonstrate the formations of tetragonal REVO4 shells based on checkup of the corresponding lattice fringes, characteristic IR absorption peaks and element signals. Their potentials for selective capture, rapid separation, and convenient mass spectra (MS) labeling of the phosphopeptides from complex proteolytic digests are explored and evaluated for the first time. The experimental results show that the magnetic γ-Fe2O3@REVO4 core-shell structured microspheres have high selective affinity for the phosphopeptides. The trapped phosphopeptides can be rapidly isolated by an external magnetic field, and can be easily identified by characteristic MS signals from 80 Da mass losses in the mass spectra (MS). Additionally, the γ-Fe2O3@REVO4 affinity materials can be reused after recovery.

Yolk-shell magnetic microspheres with mesoporous yttrium phosphate shells for selective capture and identification of phosphopeptides

Architectural design is important to achieve appropriate chemical and biological properties of nanostructures. Yolk-shell magnetic microspheres consisting of Fe3O4 cores and porous and hollow YPO4 affinity shells have been designed and constructed. The yolk-shell magnetic microspheres have a saturation magnetization (Ms) value of 48.3 emu g-1 with a negligible coercivity and remanence at 300 K and a BET specific surface area of 12.5 m2 g-1 with an average pore size of 10.1 nm for the mesoporous YPO4 shell. The novel multifunctional yolk-shell nanostructures can realize the selective capture, convenient magnetic separation and rapid identification of target phosphopeptides by taking advantage of the Fe3O4 magnetic cores and the selective YPO4 affinity shells. Sensitivity and selectivity of the affinity yolk-shell nanostructures were evaluated by digests of standard proteins and complex biosamples. 2678 unique phosphopeptides were captured and identified from the digest of mouse brain proteins. Therefore, this work will be highly beneficial for future applications in the isolation and purification of biomolecules, in particular, low-abundance phosphopeptide biomarkers.

Novel 3D flowerlike hierarchical γ-Fe2O3@xNH4F·yLuF3 core–shell microspheres tailor-made by a phase transformation process for the capture of phosphopeptides

Novel three-dimensional (3D) flowerlike hierarchical γ-Fe2O3@xNH4F·yLuF3 core-shell architectures were synthesized by a simple phase transformation route under mild conditions. The evolution of the flowerlike structure assembled by thin xNH4F·yLuF3 nanosheets has been investigated in detail. We found that an appropriate amount of NH4F and a suitable phase transformation reaction temperature are crucial for the formation of the flowerlike structure, while the calcination treatment is essential to maintain the well-defined core-shell structure. A possible formation mechanism was proposed for the phase transformation reaction and the self-assembly growth in situ. The novel composite material with large open pores, a specific surface area (26.2 m2 g-1), strong reversible magnetic response (Ms = 27.99 emu g-1), and good structural stability has been primarily applied for the selective and effective capture of phosphopeptides and it showed good performance. The obtained products may also have potential applications in areas such as water treatment, purification of biomolecules, and solid catalysis.