Jiazuan Ni

Intramolecular energy transfer mechanism between ligands in ternary rare earth complexes with aromatic carboxylic acids and 1,10-phenanthroline

Abstract A series of binary and ternary rare earth (Gd, Eu, Tb) complexes with aromatic acids and 1,10-phenanthroline have been synthesized. The lowest triplet state energies of ligands have been obtained by measuring the phosphorescence spectra of binary gadolinium complexes. By comparing the phosphorescence spectra of binary complexes with those of ternary ones, it is found that there exists another intramolecular energy transfer process from the aromatic acids to 1,10-phenanthroline besides the intramolecular energy transfer process between the aromatic acids and the central rare earth ions. The intramolecular energy transfer efficiencies have been calculated by determining phosphorescence lifetimes of binary and ternary gadolinium complexes. The luminescence properties of corresponding europium and terbium complexes are in agreement with the prediction based on energy transfer mechanism.

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.

Luminescence properties of the ternary rare earth complexes with β-diketones and 1,10-phenanthroline incorporated in silica matrix by a sol-gel method

Ternary complexes of rare earth Eu(dbm)(3).phen and Tb(acac)(3).phen (dbm = dibenzoylmethanide, acac = acetylacetone and phen = 1,10-phenanthroline) were introduced into silica gel by the sol-gel method. The result indicated that the rare earth ions (EU3+ and Tb3+) showed fewer emission lines and slightly lower emission intensities in the silica gel than in the pure rare earth complexes. The lifetimes of rare earth ions in silica gel (Eu3+ and Tb3+) doped with Eu(dbm)(3).phen and Tb(acac)(3).phen were longer than those in purl Eu(dbm)(3).phen and Tb(acac)(3).phen. A very small amount of rare earth complexes doped in a silica gel matrix can retain excellent luminescence properties

The photophysical properties of binary and ternary complexes of rare earths with conjugated carboxylic acids and 1,10-phenanthroline

Results of photophysical properties of the complexes of Gd3+, Eu3+ and Tb3+ with conjugated carboxylic acids (3,4-funandicarboxylic acid and nicotinic acid) and 1,10-phenanthroline are reported. Whether between central ions and ligands or between the two ligands, it is found that the intramolecular energy efficiency is a sensitive function of the relative positions of the resonance energy levels of the central ions and the lowest triplet states of the ligands. Couplings of rare earth ions to the ligands are discussed in detail

Development of the Affinity Materials for Phosphorylated Proteins/Peptides Enrichment in Phosphoproteomics Analysis

Reversible protein phosphorylation is a key event in numerous biological processes. Mass spectrometry (MS) is the most powerful analysis tool in modern phosphoproteomics. However, the direct MS analysis of phosphorylated proteins/peptides is still a big challenge because of the low abundance and insufficient ionization of phosphorylated proteins/peptides as well as the suppression effects of nontargets. Enrichment of phosphorylated proteins/peptides by affinity materials from complex biosamples is the most widely used strategy to enhance the MS detection. The demand of efficiently enriching phosphorylated proteins/peptides has spawned diverse affinity materials based on different enrichment principles (e.g., electronic attraction, chelating). In this review, we summarize the recent development of various affinity materials for phosphorylated proteins/peptides enrichment. We will highlight the design and fabrication of these affinity materials, discuss the enrichment mechanisms involved in different affinity materials, and suggest the future challenges and research directions in this field.

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.

Luminescence properties of rare earth (Eu3+ and Tb3+) complexes with conjugated carboxylic acids and 1,10-phenanthroline incorporated in silica matrix

Binary and ternary complexes of europium and terbium with conjugated carboxylic acid (nicotinic acid and 3,4-furandicarboxylic acid) and 1,10-phenanthroline were introduced into silica gel by the sol-gel method. The luminescence behavior of the complexes in silica gels was studied compared with the corresponding solid state complexes by means of emission, excitation spectra and lifetimes. The result indicated that the rare earth ions (EU3+ and Tb3+) showed fewer emission lines and slightly lower emission intensities in the silica gel than those in pure rare earth complexes. The lifetimes of rare earth ions (EU3+ and Tb3+) in silica gel doped with rare earth complexes became longer than those in pure rare earth complexes

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.