Titanium-containing magnetic mesoporous silica spheres: effective enrichment of peptides and simultaneous separation of nonphosphopeptides and phosphopeptides

Protein phosphorylation is a common posttranslational modification, and involved in many cellular processes. Like endogenous peptides, endogenous phosphopeptides contain many biomarkers of preclinical screening and disease diagnosis. In this work, titanium-containing magnetic mesoporous silica spheres were synthesized and applied for effective enrichment of peptides from both tryptic digests of standard proteins and human serum. Besides, the enriched peptides can be further separated into nonphosphopeptides and phosphopeptides by a simple elution. First, titanium-containing magnetic mesoporous silica spheres were synthesized by a sol-gel method and found to have high surface area, narrow pore size distribution, and useful magnetic responsivity. Then, as the prepared material was used for selective capturing of phosphopeptides, it demonstrated to have higher selectivity than commercial titanium dioxide. Moreover, via combination of size-exclusion mechanism, hydrophobic interaction, and affinity chromatography, titanium-containing magnetic mesoporous silica spheres were successfully applied to simultaneously extract and separate nonphosphopeptides and phosphopeptides from standard protein digestion and human serum.     

Simultaneous preconcentration and determination of nickel and cobalt using functionalised mesoporous silica spheres by ICP-OES

In this work functionalised mesoporous silica spheres have been utilised for the simultaneous preconcentration of nickel and cobalt. The silica spheres (SiSPs) prepared by the sol-gel method were functionalised with sodium diethyldithiocarbamate (DDTC-SiSPs). They were characterised by SEM, TEM, XRD, FTIR, CHN and nitrogen adsorption. The adsorption efficiency of DDTC-SiSPs was examined by batch equilibrium technique. The DDTC-SiSPs showed 100% adsorption for Ni (II) and Co (II). The effect of changing variables such as pH, shaking time, sample volume, preconcentration factor, eluent type and volume were investigated so as to obtain maximum recovery with high selectivity over interfering ions. The maximum adsorption capacity was found to be 15.15 mg g^?1 and 11.80 mg g^?1 for Ni (II) and Co (II) respectively using DDTC-SiSPs. 100% recovery was achieved with 5 mL of 2 M HNO₃. The maximum preconcentration factor was 400 and the 3σ limits of detection were 0.201 µg L^?1 and 0.198 µg L^?1 for Ni (II) and Co (II) respectively. Thermodynamic studies showed that adsorption of Ni (II) and Co (II) on DDTC-SiSPs is exothermic with enthalpy changes of –0.514 KJ mol^?1 and –0.854 KJ mol^?1 for Ni (II) and Co (II) respectively. The method was applied to the preconcentration and determination of Ni (II) and Co (II) from tap, river and sea water.     

Synthesis of novel mesoporous silica spheres with starburst pore canal structure

Novel spherical mesoporous silica materials with uniform diameters and starburst mesopore structures were synthesized by a simple one-step procedure with ethanol as the co-solvent in dilute aqueous solution and their formation mechanism was proposed. The arrangement of the pore canal and the diameter of the sphere could be tailored by altering the concentration of ethanol.     

Direct synthesis of amino-functionalized monodispersed mesoporous silica spheres and their catalytic activity for nitroaldol condensation

New amino-functionalized monodispersed mesoporous silica spheres (MMSS) were synthesized directly by co-condensation of 3-aminopropyltrimethoxysilane (AP-TMS), [3-(2-aminoethylamino)propyl]trimethoxysilane (AEAP-TMS) or 3-[2-(2-aminoethylamino)ethylamino]propyltrimethoxysilane (AEAEAP-TMS) with tetramethoxysilane. By changing the methanol ratio or adding extra silica source, amino-functionalized MMSS with different particle diameter (310–780 nm) and the same mesopore size were successfully synthesized. TEM observations revealed that the mesopores were aligned radially from the center towards the outside of the spheres even in the amino-functionalized MMSS. The effect of particle diameter on base catalytic activity was investigated using the amino-functionalized MMSS. In addition, the amino-functionalized MMSS were found to be excellent base catalysts in the nitroaldol condensation reactions. The effectiveness factor was evaluated to be 0.8–0.82 and improved substantially compared with MMSS prepared by grafting method.     

双模板法制备介孔二氧化硅纳米蚕茧

用十八烷基三甲基溴化铵(STAB)作模板剂,左旋香茅醇(CN)为结构助剂,利用溶胶-凝胶法,在CN/STAB摩尔比1∶1条件下制备了介孔二氧化硅纳米蚕茧;采用扫描电镜和透射电镜分析了产物的结构,并对其进行了氮气吸附-脱附测试.结果表明,所制备的介孔二氧化硅纳米蚕茧的孔道与蚕茧表面平行;搅拌速度对介孔二氧化硅纳米蚕茧的长度有较大的影响,随着搅拌速度的增加,其长度减小.     

Study of the Pm3n space group of cubic mesoporous silica.

By using a Gemini surfactant, [C14H25N+(CH3)2-(CH2)2-N+(CH3)2C14H25]2 Br-(C(14-2-14)), with a short spacer group (s = 2) as structure-directing agent and sodium silicate as precursor, high-quality, ordered cubic mesoporous silica with space group Pm3n was prepared by the S+I-route (S = surfactants, I = precursor). The samples were characterized by small-angle X-ray diffraction, transmission electron microscopy, and N2 adsorption-desorption. The results showed that the pore structure of the resulting mesoporous silica belonged to the cubic system (space group Pm3n). The unit-cell parameter of the cubic system was in the range of 8.81-9.14 nm. The high-quality cubic mesoporous structure was formed at molar ratios of C(14-2-14) to sodium silicate of 0.33:1 to 0.16:1 and a molar ratio of ethyl acetate to sodium silicate of 2:1. N2 adsorption-desorption curves revealed type IV isotherms and H1 hysteresis loops. The primary pore volume, and the most probable pore size according to the Barrett-Joyner-Halenda (BJH) model, increased with increasing molar ratio of C(14-2-14) to sodium silicate.     

Nanoencapsulation of stem cells within polyelectrolyte multilayer shells

Mouse mesenchymal stem cells have been individually encased by polyelectrolyte layers of poly (L-lysine) and hyaluronic acid using the electrostatic layer-by-layer assembly technique, resulting in a shell consisting of nanolayers of thickness around 6-9 nm. Maintenance of cell morphology and viability were demonstrated for up to one week. Further adjustments to shell permeability and flexibility will facilitate the use of these encapsulated cells in tissue engineering and targeted-delivery applications.     

介孔二氧化硅的扩孔及其氨基功能化

利用嵌段共聚物聚环氧乙烷-聚环氧丙烷-聚环氧乙烷(P123)作为胶束模板,均三甲苯(TMB)为扩孔剂,在强酸条件下制备出了一系列大孔径的介孔二氧化硅材料,获得了一种泡状新型结构的硅材料;通过N2吸附-脱附、高分辨透射电镜(HTEM)等手段对这种新型结构的材料进行了表征,综合考察了扩孔剂的用量、酸的浓度以及水热处理温度对...     

Polyelectrolyte multilayers prepared on hydrogel surfaces

Poly(vinyl alcohol) hydrogels were alternately immersed in aqueous solutions of oppositely charged polymers. The adsorption of the cationic dye methylene blue to the immersed hydrogels suggested the presence of a coating on the hydrogel surfaces. Static contact angles with an air bubble in water showed layer‐by‐layer growth of the films. The films could be transferred onto solid substrates for mechanical strength after the hydrogels were placed on the solid substrates, and this resulted in an estimation of the film thickness. The number of assembly steps could regulate the film thickness. We present here coatings of hydrogels with thin polymer films prepared by layer‐by‐layer assembly. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1062–1067, 2005     

Microgel-based engineered nanostructures and their applicability with template-directed layer-by-layer polyelectrolyte assembly in protein encapsulation

A novel strategy for the fabrication of microcapsules is elaborated by employing biomacromolecules and a dissolvable template. Calcium carbonate (CaCO(3)) microparticles were used as sacrificial templates for the two-step deposition of polyelectrolyte coatings by surface controlled precipitation (SCP) followed by the layer-by-layer (LbL) adsorption technique to form capsule shells. When sodium alginate was used for inner shell assembly, template decomposition with an acid resulted in simultaneous formation of microgel-like structures due to calcium ion-induced gelation. An extraction of the calcium after further LbL treatment resulted in microcapsules filled with the biopolymer. The hollow as well as the polymer-filled polyelectrolyte capsules were characterized using confocal laser scanning microscopy (CLSM), scanning electron microscopy (SEM), and scanning force microscopy (SFM). The results demonstrated multiple functionalities of the CaCO(3) core - as supporting template, porous core for increased polymer accommodation/immobilization, and as a source of shell-hardening material. The LbL treatment of the core-inner shell assembly resulted in further surface stabilization of the capsule wall and supplementation of a nanostructured diffusion barrier for encapsulated material. The polymer forming the inner shell governs the chemistry of the capsule interior and could be engineered to obtain a matrix for protein/drug encapsulation or immobilization. The outer shell could be used to precisely tune the properties of the capsule wall and exterior. [Diagram: see text] Confocal laser scanning microscopy (CLSM) image of microcapsules (insert is after treating with rhodamine 6G to stain the capsule wall).     

Colloidal single crystals of silica spheres in the presence of simple- and poly-electrolytes,and ionic detergents

Colloidal single crystals of silica spheres (103 nm in diameter) are formed in the presence of various kinds of salts 1 simple electrolytes, i.e., sodium chloride, calcium chloride and lanthanum chloride, 2 polyelectrolytes such as 3–6 type ionen polymer (polybrene), poly-N-ethylpyridinium bromide, a copolymer ofN-benzyl pyridinium chloride andN-hexadecyl pyridinium bromide, and sodium polyethylene sulfonate, and 3 cationic and anionic detergents, hexadecyltrimethylammonium bromide and sodium dodecylsulfate. Shape and size of their single crystals, phase diagram, and the relationship between the two parameters among the critical concentration of melting, conductance and pH of the crystal-like suspensions have been studied. Colloidal single crystals ofpositively charged spheres have been formed in this study by the method of the charge reversal of spheres through the strong adsorption of cationic polyelectrolytes onto the anionic silica spheres.     

可见光下改性的纳米孔二氧化硅(LUS-1)光催化苯直接羟基化合成苯酚(英文)

Fe-g-C3N4-LUS-1 was prepared by the thermal decomposition of dicyandiamide inside the pores of LUS-1 under an inert atmosphere.It was used as a photocatalyst for the hydroxylation of benzene to phenol in sunlight.The catalysts were characterized by Fourier transform infrared spectroscopy,N2 adsorption-desorption,X-ray diffraction,and scanning electron microscopy.In Fe-g-C3N4-LUS-1,a single layer of graphitic carbon nitride(g-C3N4) was formed on the surface of LUS-1.The photocatalytic activity of the iron containing g-C3N4 based catalysts was investigated,and the catalytic activity was remarkably enhanced when the reaction condition was changed from dark to sunlight.The best result was obtained with 20%Fe-g-C3N4-LUS-1 in sunlight.     

以手性两亲小分子自组装体为模板制备介孔二氧化硅空心球

合成了手性阳离子型两亲性小分子化合物,利用圆二色谱分析了其在水中形成的自组装体的结构;以该化合物的自组装体为模板,在正丙醇和氨水的混合溶剂中制备得到了介孔二氧化硅空心球;利用扫描电镜、透射电镜、X射线衍射仪以及氮气吸附-脱附试验装置分析了二氧化硅空心球的形貌及孔结构.结果表明,两亲性小分子在水中形成的自组装体呈现手性堆积;合成的介孔二氧化硅空心球的直径约为600~800nm,壁厚约为100~150nm,其孔道垂直于球的表面,孔径约为3.0nm,比表面积约为306m2·g-1.正丙醇作为模板控制二氧化硅空心球的空腔尺寸和形貌,而两亲性小分子的自组装体作为模板控制放射状孔道的形貌和尺寸.     

The responses of preosteoblasts to collagen/hyaluronic acid polyelectrolyte multilayer coating on titanium

The purpose of this study was to investigate the effect of Collagen/hyaluronic acid (Col/HA) polyelectrolyte multilayer (PEM) coating on the behaviors and function of pre‐osteoblastic cells. Col/HA PEM coating was fabricated on acid etched Ti disc via layer‐by‐layer technique. The formation and properties of Col/HA PEM coating were investigated using scanning electron microscope (SEM), contact angle and quartz crystal microbalance (QCM). Moreover, mouse preosteoblasts were used to evaluate the effect of Col/HA PEM coating on cell behaviors and function. The results of in vitro evaluations showed that the Col/HA PEM coating could accelerate the proliferation and differentiation of preosteoblasts cells. Copyright © 2011 John Wiley & Sons, Ltd.     

Coating electrospun chitosan nanofibers with polyelectrolyte multilayers using the polysaccharides heparin and N,N,N-trimethyl chitosan

A new method is presented for functionalizing electrospun nanofibers with GAGs and growth factors by PEM deposition. Electrospun chitosan nanofibers, spun from trifluoroacetic acid and dichloromethane, were coated with PEMs, using the polysaccharides heparin and N,N,N-trimethyl chitosan. FGF-2 was adsorbed on the PEM-coated nanofibers. Nanofiber neutralization, PEM construction, and FGF-2 adsorption were monitored using FT-IR spectroscopy and X-ray photoelectron spectroscopy. Alcian blue staining was used to confirm the presence of heparin. SEM was used to study nanofiber morphology.     

Palladium nanoparticles embedded in improved mesoporous silica: a pH‐triggered phase transfer catalyst for Sonogashira reaction

An efficient and reusable pH‐responsive mesoporous silica nanocomposite shuttle‐supported palladium catalyst was synthesized, which efficiently promotes the Sonogashira reaction in water‐based biphasic systems. This catalyst of shell‐embedded palladium nanoparticles is highly dispersed in organic phase in a pH range from 9 to 10 just like a homogeneous catalyst, and can be separated and reused like a heterogeneous one by adjusting the pH value of the aqueous medium. In addition, Sonogashira reactions can be performed without a copper co‐catalyst. Copyright © 2015 John Wiley & Sons, Ltd.