Facile fabrication of hydrophilic PAA-Ti/TiO2 nanocomposite for selective enrichment and detection of phosphopeptides from complex biological samples

Highly selective enrichment of trace phosphorylated proteins or peptides from complex biological samples is of profound significance for the discovery of disease biomarkers in biological systems. In this study, a novel affinity material has been synthesized to improve the enrichment specificity for phosphopeptides by using PAAS as coupling molecule. In the resulting materials, highly abundant titanium is available for selective enrichment of phosphopeptides, with plenty of carboxylate groups that can inhibit nonspecific adsorption. The enrichment results demonstrated that the hydrophilic PAA-Ti/TiO₂ composite possesses excellent selectivity for phosphopeptides even at a very low molar ratio of phosphopeptides/non-phosphopeptides (1:1000), extreme sensitivity (the detection limit was at the fmol level), and high recovery of phosphopeptides (as high as 78%). Moreover, the as-prepared nanocomposite provides effective enrichment of phosphopeptides from real samples (mouse liver), showing great potential in the detection of low-abundance phosphopeptides in biological samples.     

Mesoporous TiO2 aerogel for selective enrichment of phosphopeptides in rat liver mitochondria

The enrichment of low abundance phosphopeptides before MS analysis is a critical step for in-depth phosphoproteome research. In this study, mesoporous titanium dioxide (TiO₂) aerogel was prepared by precipitation and supercritical drying. The specific surface area up to 490.7 m² g⁻¹ is achieved by TiO₂ aerogel, much higher than those obtained by commercial TiO₂ nanoparticles and by the latest reported mesoporous TiO₂ spheres. Due to the large specific surface area and the mesoporous structure of the aerogel, the binding capacity for phosphopeptides is six times higher than that of conventional TiO₂ microparticles (173 vs 28 μmol g⁻¹). Because of the good compatibility of enrichment procedure with MALDI-TOF-MS and the large binding capacity of TiO₂ aerogel, a detection limit as low as 30 amol for analyzing phosphopeptides in β-casein digest was achieved. TiO₂ aerogel was further applied to enrich phosphopeptides from rat liver mitochondria, and 266 unique phosphopeptides with 340 phosphorylation sites, corresponding to 216 phosphoprotein groups, were identified by triplicate nanoRPLC-ESI-MS/MS runs, with false-positive rate less than 1% at the peptide level. These results demonstrate that TiO₂ aerogel is a kind of promising material for sample pretreatment in the large-scale phosphoproteome study.     

Preparation and characterization of SiO2/TiO2 composite microspheres with microporous SiO2 core/mesoporous TiO2 shell

SiO₂/TiO₂ composite microspheres with microporous SiO₂ core/mesoporous TiO₂ shell structures were prepared by hydrolysis of titanium tetrabutylorthotitanate (TTBT) in the presence of microporous silica microspheres using hydroxypropyl cellulose (HPC) as a surface esterification agent and porous template, and then dried and calcined at different temperatures. The as-prepared products were characterized with differential thermal analysis and thermogravimetric (DTA/TG), scanning electron microscopy (SEM), X-ray diffraction (XRD), nitrogen adsorption. The results showed that composite particles were about 1.8 μm in diameter, and had a spherical morphology and a narrow size distribution. Uniform mesoporous titania coatings on the surfaces of microporous silica microspheres could be obtained by adjusting the HPC concentration to an optimal concentration of about 3.2 mmol L⁻¹. The anatase and rutile phase in the SiO₂/TiO₂ composite microspheres began to form at 700 and 900 °C, respectively. At 700 °C, the specific surface area and pore volume of the SiO₂/TiO₂ composite microspheres were 552 and 0.652 mL g⁻¹, respectively. However, at 900 °C, the specific surface area and pore volume significantly decreased due to the phase transformation from anatase to rutile.     

CTAB-assisted synthesis of mesoporous F-N-codoped TiO2 powders with high visible-light-driven catalytic activity and adsorption capacity

This article describes the preparation of mesoporous rod-like F-N-codoped TiO₂ powder photocatalysts with anatase phase via a sol-gel route at the temperature of 373 K, using cetyltrimethyl ammonium bromide (CTAB) as surfactant. The as-prepared photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and UV-visible diffuse reflectance spectra (UV-vis DRS). The results showed that the photocatalysts possessed a homogeneous pore diameter and a high surface area of 106.3-160.7 m³ g⁻¹. The increasing CTAB reactive concentration extended the visible-light absorption up to 600 nm. The F-N-codoped TiO₂ powders exhibited significant higher adsorption capacity for methyl orange (MO) than that of Degussa P25 and showed more than 6 times higher visible-light-induced catalytic degradation for MO than that of P25.     

Preparation and characterization of mesoporous TiO2-CeO2 nanopowders respond to visible wavelength

Mesoporous TiO₂-CeO₂ nanopowders responding to visible wavelength were synthesized by using a surfactant assisted sol-gel technique. They were obtained using metal alkoxide precursors modified with acetylacetone (ACA) and laurylamine hydrochloride (LAHC) as surfactant. The samples were characterized by XRD, nitrogen adsorption isotherm, SEM, TEM, and selected area electron diffraction (SAED), respectively. The 95 mol% TiO₂-5 mol% CeO₂ system yielded single anatase phase, however, further addition of the CeO₂ formed cubic CeO₂ structure while anatase TiO₂ decreased. Additions of 5 and 10 mol% CeO₂ increased the surface area, but those of 25, 50, and 75 mol% CeO₂ did not affect it very much. By using this mixed metal oxides system, TiO₂ can be modified to respond to the visible wavelength. The mixed metal oxides had catalytic activity (evaluating the formation rate of I₃⁻) about 2-3 times higher than pure CeO₂, while nanosize anatase type TiO₂ materials had no catalytic activity under visible light. The catalytic activity was almost proportional to the specific surface area. The formation rate of I₃⁻ was much improved by changing the calcination temperature and calcination period. Highest catalytic activity in this study was obtained for the 50 mol% TiO₂-50 mol% CeO₂ nanopowders calcined at 250 °C for 24 h.     

High lithium electroactivity of hierarchical porous rutile TiO2 nanorod microspheres

Here we report on the hierarchical porous rutile TiO₂ nanorod micospheres as an anode material for lithium-ion batteries. The resulting hierarchical porous rutile TiO₂ nanorod microspheres possessed much higher reversible capacity, cycling stability and rate capability than nanosized rutile TiO₂ previously reported in the literatures. These good electrochemical performances may be attributed to the facile diffusion of Li⁺ ions from outside through the porous channels into the TiO₂ nanorods in the microspheres and the high electrode–electrolyte contact area offered by hierarchical porous microspheres with a large specific surface area.     

Preparation of monodispersed microporous SiO2 microspheres with high specific surface area using dodecylamine as a hydrolysis catalyst

A novel and simple method for the synthesis of monodispersed microporous SiO₂ microspheres with high specific surface area was developed by hydrolysis of tetraethoxysilane (TEOS) in a water-ethanol mixed solution and using dodecylamine (DDA) as hydrolysis catalyst and template. The as-prepared products were characterized with differential thermal analysis-thermogravimetry, scanning electron microscopy, high-resolution transmission electron microscopy, small angle X-ray diffraction and nitrogen adsorption. The effects of experimental conditions including hydrolysis temperatures, calcination temperature and concentrations of TEOS and DDA on the morphology and pore parameters of the as-prepared SiO₂ microspheres were investigated and discussed. The results showed that hydrolysis temperature and concentrations of TEOS and DDA are important parameters for the control of size and morphology of particles. The specific surface area and specific pore volume of the as-prepared SiO₂ microspheres increased with increasing DDA concentration and calcination temperature. DDA may act not only as a good hydrolysis catalyst but also as a template for the formation of monodispersed SiO₂ microspheres with high specific surface area. This research may provide new insight into the synthesis of monodispersed microporous SiO₂ microspheres.     

TiO2/Cu2O/Pt复合空心微球的制备及其光催化性能

以锐钛矿相TiO₂溶胶为基底,采用沉淀法和液相沉积法制备了TiO₂/Cu₂O/Pt复合空心微球,通过改变n₍Ti⁴⁺)∶n_Cu2+和H₂Pt Cl₆·6H₂O溶液的加入量对TiO₂的形貌和结构进行调控,采用不同的方法对不同样品的物相及结构、微观形貌和光学性能进行了对比分析。分析结果表明,复合材料中Pt与Cu₂O的引入产生协同效应,不仅在一定程度上阻止了电子-空穴的复合,还降低了禁带宽度,在可见光区域光吸收明显增强。与TiO₂、Cu₂O和TiO₂/Cu₂O光催化剂相比较,TiO₂/Cu₂O/Pt降解有机污染物的能力显著增强,首次光照120 min可降解93%的甲基橙(MO)溶液,4次循环后降解率为71%,具有良好的光催化...     

TiO2/Cu2O/Pt复合空心微球的制备及其光催化性能

以锐钛矿相TiO₂溶胶为基底,采用沉淀法和液相沉积法制备了TiO₂/Cu₂O/Pt复合空心微球,通过改变n_Ti⁴⁺∶ n_Cu²⁺和H₂PtCl₆·6 H₂O溶液的加入量对TiO₂的形貌和结构进行调控,采用不同的方法对不同样品的物相及结构、微观形貌和光学性能进行了对比分析。分析结果表明,复合材料中Pt与Cu₂O的引入产生协同效应,不仅在一定程度上阻止了电子-空穴的复合,还降低了禁带宽度,在可见光区域光吸收明显增强。与TiO₂、Cu₂O和TiO₂/Cu₂O光催化剂相比较,TiO₂/Cu₂O/Pt降解有机污染物的能力显著增强,首次光照120 min可降解93%的甲基橙(MO)溶液,4次循环后降解率为71%,具有良好的光催化稳定性能。     

Phosphate-functionalized magnetic microspheres for immobilization of Zr ions for selective enrichment of the phosphopeptides

In this work, we developed phosphate functionalized magnetic Fe₃O₄@C microspheres to immobilize Zr⁴⁺ ions for selective extraction and concentration of phosphopeptides for mass spectrometry analysis. Firstly, we synthesized Fe₃O₄@C magnetic microspheres as our previous work reported. Then, the microspheres were functionalized with phosphate groups through a simple hydrolysis reaction using 3-(trihydroxysilyl)propyl methylphosphate. And the Zr⁴⁺ ions were immobilized on phosphate-functionalized magnetic microspheres by using phosphate chelator. Finally, we successfully employed Zr⁴⁺-phosphate functionalized magnetic microspheres to selectively isolate the phosphopeptides from tryptic digests of standard protein and real samples including rat brain. All the experimental results demonstrate the enrichment efficiency and selectivity of the method we reported here.     

Photocatalytic hydrogen evolution over mesoporous TiO2/metal nanocomposites

Na⁺ complex with the dibenzo-18-crown-6 ester was used as a template to synthesize mesoporous titanium dioxide with the specific surface area 130–140 m²/g, pore diameter 5–9 nm and anatase content 70–90%. The mesoporous TiO₂ samples prepared were found to have photocatalytic activity in Cu^II, Ni^II and Ag^I reduction by aliphatic alcohols. The resulting metal–semiconductor nanostructures have remarkable photocatalytic activity in hydrogen evolution from water–alcohol mixtures, their efficiency being 50–60% greater than that of the metal-containing nano-composites based on TiO₂ Degussa P25.The effects of the thermal treatment of mesoporous TiO₂ upon its photocatalytic activity in hydrogen production were studied. The anatase content and pore size were found to be the basic parameters determining the photoreaction rate. The growth of the quantum yield of hydrogen evolution from TiO₂/Ag⁰ to TiO₂/Ni⁰ to TiO₂/Cu⁰ was interpreted in terms of differences in the electronic interaction between metal nanoparticles and the semiconductor surface. It was found that there is an optimal metal concentration range where the quantum yield of hydrogen production is maximal. A decrease in the photoreaction rate at further increment in the metal content was supposed to be connected with the enlargement of metal nanoparticles and deterioration of the intimate electron interaction between the components of the metal–semiconductor nanocomposites.     

Characterization of mesoporous nanocrystalline TiO2 photocatalysts synthesized via a sol-solvothermal process at a low temperature

Nanocrystalline TiO₂ samples with mesoporous structure were prepared via a solvothermal treatment of surfactant-stabilized TiO₂ sols. The samples were obtained from media of different acidities including nitric acid, deionized water, and ammonia (denoted as HT-1, HT-2 and HT-3, respectively). These samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), N₂-sorption (BET surface area), micro-Raman spectroscopy, infrared absorption spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). The photocatalytic activities of the samples were tested by the self-photosensitized degradation of an azo dye, Mordant Yellow 10 (MY), in aqueous solution under visible light irradiation. The results reveal that all three samples have high surface area and are pure anatase phase. The sample prepared in nitric acid medium possesses the most ideal mesoporous structure and also exhibits a blue shift in the Raman spectrum. All three samples show much higher photocatalytic activity than the commercial P-25. The activity order of the three samples is HT-1>HT-2>HT-3.     

Catalytic oxidation of no to NO2 over Cr/TiO2 and Cu/TiO2 under oxidizing atmosphere

The catalytic activity of Cr/TiO₂ and Cu/TiO₂ for the oxidation of NO under an oxidizing atmosphere has been examined. Both catalysts had excellent ability for the oxidation of NO to NO₂ in the temperature range of 350–400°C.     

Top-down synthesized TiO2 nanowires as a solid matrix for surface-assisted laser desorption/ionization time-of-flight (SALDI-TOF) mass spectrometry

Top-down synthesized TiO₂ nanowires are presented as an ideal solid matrix to analyze small biomolecules at a m/z of less than 500. The TiO₂ nanowires were synthesized as arrays using a modified hydrothermal process directly on the surface of a Ti plate. Finally, the feasibility of the TiO₂ nanowires in the anatase phase as a solid matrix. The crystal and electronic structures of the top-down TiO₂ nanowires were analyzed at each step of the hydrothermal process, and the optimal TiO₂ nanowires were identified by checking their performance toward the ionization of analytes in surface-assisted laser desorption/ionization time-of-flight (SALDI-TOF) mass spectrometry. Finally, the feasibility of the TiO₂ nanowires in the anatase phase as a solid matrix for SALDI-TOF mass spectrometry was demonstrated using eight types of amino acids and peptides as model analytes.     

高电化学活性SnO2/TiO2空心微球的制备及其性能

采用一种简便的无模板溶剂热法合成了尺寸在1μm左右、具有堆叠结构的SnO_2/TiO_2空心微球。合成过程的研究结果表明:SnO_2/TiO_2空心微球在形成过程中经历了空心、被填充、分裂到再次形成空心结构的过程。随后,SnO_2/TiO_2空心微球作为锂离子电池负极材料的电化学性能测试结果表明:SnO_2/TiO_2空心微球在0.1 A·g~(-1)的电流密度下,其首次放电容量达到1 484.9mAh·g~(-1),库伦效率为49.0%。经过600次循环后,其放电容量依然可以达到565.6 mAh·g~(-1),显示了高的容量和循环稳定性。     

TiO2/SnO2复合光催化剂的耦合效应

采用改进的sol gel技术制备TiO2/SnO2耦合型半导体光催化剂,利用XRD、气相色谱 仪、粒度仪和表面光电压装置等研究了耦合型半导体光催化机理和光催化效率的影响因素, 并通过降解甲醛探讨其在空气污染治理中的作用.实验结果表明,添加20 ％(mol) SnO2的复 合半导体光催化剂,其光催化效率比纯TiO2高一倍以上.据实验结果和粒子紧密堆积原理,提 出强耦合效应和弱耦合效应的光催化反应模型,并用此模型较好地解释了TiO2/SnO2复合型半 导体光催化剂的光催化效率随SnO2含量变化规律.     

Preparation, characterization, and infrared emissivity property of optically active polyurethane/TiO2/SiO2 multilayered microspheres

Optically active polyurethane/titania/silica (LPU/TiO₂/SiO₂) multilayered core–shell composite microspheres were prepared by the combination of titania deposition on the surface of silica spheres and subsequent polymer grafting. LPU/TiO₂/SiO₂ was characterized by FT-IR, UV–vis spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), SEM and TEM, and the infrared emissivity value (8–14 μm) was investigated in addition. The results indicated that titania and polyurethane had been successfully coated onto the surfaces of silica microspheres. LPU/TiO₂/SiO₂ exhibited clearly multilayered core–shell construction. The infrared emissivity values reduced along with the increase of covering layers thus proved that the interfacial interactions had direct influence on the infrared emissivity. Besides, LPU/TiO₂/SiO₂ multilayered microspheres based on the optically active polyurethane took advantages of the orderly secondary structure and strengthened interfacial synergistic actions. Consequently, it possessed the lowest infrared emissivity value.     

Synthesis of bimodal porous structured TiO2 microsphere with high photocatalytic activity for water treatment

In this work bimodal structured titanium dioxide (TiO₂) microsphere has been prepared from commercial TiO₂ powder and nano-sized titania gel via sol–gel spray-coating technique. Crystallization and transformation behavior of titania gel were investigated. The results revealed that the crystallization and transformation of anatase particles were substantially affected by the concentration of solvent and calcination temperature. Anatase crystallite size of 10 nm was obtained at mole ratio of solvent/precursor 50/1 and calcination temperature of 450 °C. The prepared nano-sized titania gel was embedded within the core (commercial TiO₂, P25) during the spraying process. The prepared TiO₂ microsphere was characterized using X-ray diffractometer (XRD), scanning electron microscope (SEM), field emission electron microscope (FESEM) and micropore analysis. The photocatalytic activity was monitored by following the degradation of phenol with activity benchmarked against commercial P25 (Degussa). The increase of photocatalytic activity of TiO₂ microsphere was attributed to the nano-sized anatase crystallite which has been incorporated into the TiO₂ microsphere.     

Synthesis and visible light photocatalysis of Fe-doped TiO2 mesoporous layers deposited on hollow glass microbeads

Nano-composite of Fe-doped anatase TiO₂ nanocrystals loaded on the hollow glass microbeads was prepared by co-thermal hydrolysis deposition and calcining treatment. The adherence of TiO₂ mesoporous layers to the surfaces of hollow glass microbeads prevented the aggregation of TiO₂ nanoparticles and benefited to their catalytic activity. The doping of Fe ions makes the absorption edge of the TiO₂ based nano-composite red-shifted into the visible region. An effective photodegradation of the methyl orange aqueous solution was achieved under visible light (λ>420 nm) irradiation, revealing the potential applicability of such nano-composite in some industry fields, such as air and water purifications.     

Synthesis and photocatalytic activity of co-doped mesoporous TiO2 on Brij98/CTAB composite surfactant template

Using composite surfactant templates, polyoxyethylene (20) oleyl ether (Brij98) and cetyl trimethyl ammonium bromide (CTAB), as structure-directing agents, N and La co-doped mesoporous TiO₂ complex photocatalysts were synthesized successfully. The micromorphology of co-doped mesoporous TiO₂ samples was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transformed infrared spectroscopy (FT-IR), energy-dispersive X-ray spectrometer (EDS) and N₂ adsorption-desorption measurements. The results indicated that the complex photocatalyst prepared with a molar ratio of Brij98:CTAB=1:1 showed a uniform pore size of ca. 7 nm and a high specific surface area (S_BET) of 279.0 m² g⁻¹, and exhibited the highest photocatalytic activity for degradation of papermaking wastewater under ultra-violet light irradiation. The chemical oxygen demand (CODc_r) percent degradation was about 73% in 12 h and chroma percent degradation was 100% in 8 h.