De-Hui Sun

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.

Novel Ti4+-chelated magnetic nanostructured affinity microspheres containing N-methylene phosphonic chitosan for highly selective enrichment and rapid separation of phosphopeptides

Magnetic composite particles immobilized with metal affinity ions show high potential in the phosphoproteome mass-spectrometric (MS) analysis. However, the preparation of this kind of material still suffers from a complicated synthesis procedure and high cost. In this work, the magnetic nanostructured composite microspheres (MPCS) incorporated into N-methylene phosphonic chitosan were first fabricated via a facile one-pot synthesis strategy and titanium ions (Ti4+) were subsequently immobilized onto the MPCS to form MPCS-Ti4+ affinity particles. The uniform spherical MPCS-Ti4+ affinity particles with abundant chelated titanium ions have a particle size distribution between 126 nm and 280 nm, and they display superparamagnetism with a saturation magnetization (Ms) value of 44.75 emu g-1. The amount of the immobilized Ti4+ ions was estimated to be 11.6 wt% by EDS. The MPCS-Ti4+ exhibited excellent dispersibility in aqueous solution, high affinity selectivity for phosphopeptides and quite fast magnetic separation within 10 s as well as good reusability. Thus, the prepared magnetic MPCS-Ti4+ nanostructured affinity materials will possess great potential in phosphoproteome research.

Synthesis and characterization of terbium(III)-pyromellitic acid (H4L)-1,10-phenanthroline (phen) luminescent complex

Abstract The terbium(III)-pyromellitic acid(H4L)-1,10-phenanthroline(phen) luminescent complex was synthesized using a co-precipitation method. The chemical composition of the synthesized complex was speculated to be Tb4L3(phen)0.075·10H2O by elemental analysis, inductively coupled plasma-atomic emission spectroscopy (ICP-AES), and Fourier-transform infrared spectroscopy (FT-IR). The X-ray diffraction analytic results indicated that the synthesized complex is a new crystalline complex, whose structure was different from those of other two ligands. The scanning electron microscopy analytic results showed that the product was of spherical crystals with good dispersion property, and the mean diameter of the spheres was about 1-2 μm. The TG-DTA result showed that the complex had good stability below 489 °C. PL spectra showed that the complex emitted characteristic green fluorescence of Tb(III) ion under ultraviolet excitation.