Cadmium Tellurium Quantum Dots in Sol-Gel-Derived Silica Spheres Coated with Calix[6]Arene as an Optical Probe for Dalapon

This paper reports a new optical probe for detect dalapon. We have synthesized the luminescent and stable CdTe quantum dots(QDs) capped with calix[6]arene(C[6]/SiO₂/CdTe) via the sol-gel technique in aqueous media. These hybrid organic-inorganic compounds are characterized by IR spectroscopy, ultraviolet-visible spectroscopy (UV-vis), transmission electron microscopy (TEM), and fluorescence. We found that the C[6]/SiO₂/CdTe were more stable and had higher fluorescence than the SiO₂/CdTe nanoparticles (NPs). The C[6]/SiO₂/CdTe show selectivity and sensitivity to dalapon via significant fluorescence intensity decrease. It can be ascribed to the Stern-Volmer equation. Under the optimal conditions, the relative fluorescent intensity was decreased linearly with increasing dalapon concentration in the range of 1.0–25.0 nmol/L with a detection limit of 0.262 nmol/L of dalapon. The possible underlying mechanism is discussed by Langmuir binding isotherm.     

Tandem Transesterification–Esterification Reactions Using a Hydrophilic Sulfonated Silica Catalyst for the Synthesis of Wintergreen Oil from Acetylsalicylic Acid Promoted by Microwave Irradiation

SiO₂–SO₃H, with a surface area of 115 m²/g and pore volume of 0.38 cm³g⁻¹, and 1.32 mmol H⁺/g was used as a 20% w/w catalyst for the preparation of methyl salicylate (wintergreen oil or MS) from acetylsalicylic acid (ASA). A 94% conversion was achieved in a microwave reactor over 40 min at 120 °C in MeOH. The resulting crude product was purified by flash chromatography. The catalyst could be reused three times.     

Drug Encapsulation and Release by Mesoporous Silica Nanoparticles: The Effect of Surface Functional Groups

Mesoporous silica nanoparticles (MSNPs) have been widely used as drug carriers for stimuli‐responsive drug delivery. Herein, a catalysis screening technique was adopted for analyzing the effects of chain length, terminal group, and density of disulfide‐appended functional ligands on the surface of MSNPs on drug‐loading capacity and glutathione‐triggered drug‐release kinetics. The ligand with an intermediate length (5 carbon atoms) and a bulky terminal group (cyclohexyl) that complexes with theβ‐cyclodextrin ring showed the highest drug loading capacity as well as good release kinetics. In addition, decreasing the surface coverage of the functional ligands led to an enhancement in drug release. In vitro drug‐delivery experiments on a melanoma cell line (B16‐F10) by using the functionalized MSNPs further supported the conclusion. The results obtained may serve as a general guide for developing more effective MSNP systems for drug delivery.     

Evaluation of Chitosan Derivatives Modified Mesoporous Silica Nanoparticles as Delivery Carrier

Chitosan is a non-toxic biological material, but chitosan is insoluble in water, which hinders the development and utilization of chitosan. Chitosan derivatives N-2-Hydroxypropyl trimethyl ammonium chloride (N-2-HACC) and carboxymethyl chitosan (CMCS) with good water solubility were synthesized by our laboratory. In this study, we synthesized mesoporous SiO₂ nanoparticles by the emulsion, and then the mesoporous SiO₂ nanoparticles were modified with γ-aminopropyltriethoxysilane to synthesize aminated mesoporous SiO₂ nanoparticles; CMCS and N-2-HACC was used to cross-link the aminated mesoporous SiO₂ nanoparticles to construct SiO₂@CMCS-N-2-HACC nanoparticles. Because the aminated mesoporous SiO₂ nanoparticles with positively charged can react with the mucous membranes, the virus enters the body mainly through mucous membranes, so Newcastle disease virus (NDV) was selected as the model drug to evaluate the performance of the SiO₂@CMCS-N-2-HACC nanoparticles. We prepared the SiO₂@CMCS-N-2-HACC nanoparticles loaded with inactivated NDV (NDV/SiO₂@CMCS-N-2-HACC). The SiO₂@CMCS-N-2-HACC nanoparticles as delivery carrier had high loading capacity, low cytotoxicity, good acid resistance and bile resistance and enteric solubility, and the structure of NDV protein encapsulated in the nano vaccine was not destroyed. In addition, the SiO₂@CMCS-N-2-HACC nanoparticles could sustain slowly released NDV. Therefore, the SiO₂@CMCS-N-2-HACC nanoparticles have the potential to be served as delivery vehicle for vaccine and/or drug.     

基质环境对氨基苯甲酸/硅凝胶复合材料荧光特性的影响

近年来，溶胶－凝胶技术在制备无机－有机复合材料中的应用越来越广泛犤１～６犦。该方法既可以制得具有很好机械性能和光学均匀性的块体材料，也可以制得薄膜和粉体材料。有机光学活性物质在无机基质中的存在状态及其化学环境，有机分子之间及有机分子与无机基质之间的相互作用对材料的热稳定性、光学特性以及实际应用影响极大犤７～１０犦。研究无机基质的微环境与有机光学活性分子之间的相互作用，对于复合材料的组成、性能、制备工艺的优化设计和实际应用至关重要。但是，目前有关这方面的系统研究报道很少。本文在硅溶胶中分别掺入了一…     

Trimethylsilyl Protection of Alcohols Over Phosphorus Pentoxide Supported on Silica Gel

Abstract

An eco-friendly and mild protocol for trimethylsilyl protection of alcohols over phosphorus pentoxide supported on silica gel using hexamethyldisilazane has been described. Solvent-free and ambient reaction conditions, easy workup, short reaction times, excellent yields, and reusability of the catalyst are the noticeable features of this methodology.

GRAPHICAL ABSTRACT     

SiO2纳米颗粒与聚氧乙烯对Pickering乳液的协同稳定作用简

研究了聚氧乙烯(PEO)与SiO2纳米颗粒对水/二甲苯体系Pickering乳液的协同稳定作用. 实验发现,PEO的存在减小了乳液液滴的平均直径,抑制了乳液的相反转,有效阻止了乳液的熟化,使乳液具有更好的稳定性. 进一步对纳米颗粒膜的流变性质进行研究,结果表明,PEO高分子促进了纳米颗粒形成更大尺寸的聚集结构,提高了其在界面上的吸附性,增强了颗粒膜的力学性能,在较小颗粒用量条件下使得Gibbs稳定性判据得到满足.     

SiO2@CdTe@Au复合纳米粒子的制备与非线性吸收特性

应用SiO₂纳米粒子、CdTe量子点和Au纳米粒子,采用逐层吸附法制备SiO₂@CdTe@Au纳米复合材料。同时对样品进行了测试和表征,从多个方面证明纳米复合材料成功制备。利用Z扫描技术测量了SiO₂@CdTe和SiO₂@CdTe@Au纳米复合材料在纳秒激光脉冲作用下的非线性吸收光学特性。实验结果表明：SiO₂@CdTe和SiO₂@CdTe@Au纳米复合材料均表现出饱和吸收特性。SiO₂@CdTe@Au较SiO₂@CdTe纳米复合材料具有更强的非线性光学特性,并对其机理进行了分析。     

Effects of pH During the Base Catalyzed Reaction of Two-Step Acid/Base Catalyzed Process on the Microstructures and Physical Properties of Poly(dimethylsiloxane) Modified Silica Xerogels

Poly(dimethylsiloxane) (PDMS) modified silica xerogels were prepared by two-step acid/base catalyzed sol-gel process. By keeping the acid amount and hydrolysis period in acidic environment fixed, and adding different amounts of base to the sol afterwards, attempts had been made to study the effect of the different amounts of base catalyst on the micro-structure and physical properties of the prepared ORMOSILs. DTA, SEM, BET, FTIR were performed to characterize the derived specimens. The microstructure and physical properties are greatly influenced by the amount of base added to the sol. With increasing base content the crystallite size and porosity increase and the pore size distribution takes a broad spectrum. Whereas, the glass transition temperature seems to decrease with increasing of base catalyst amount. This is explained in terms of the change in the relative amounts of hydrolysis and condensation reactions due to the addition of different amount of base catalyst, which predominantly influences the condensation reactions. The results are reported in this communication along with possible explanations behind the observations.     

Preparation and Optical Properties of Submicron SiO2 Spheres Doped with YAG:Nd3+ Nanocrystallites

The sol-gel technology has been applied to obtain SiO₂ spheres of submicron size. The spheres have been doped with YAG:Nd³⁺ nanocrystallites. The nanocrystallites have been obtained from aqueous solutions of citric acid, yttrium, aluminum and neodymium chlorides. The obtained gels have been heated up to 800°C. Emission spectra as well as the excited state lifetimes have been measured at room and liquid nitrogen temperatures. The structural characterization has been performed by means of transmission and scanning electron microscopies (TEM, SEM) and powder diffraction (XRD) measurements. We have observed that the YAG:Nd³⁺ nanocrystallites demonstrate pronounced dependence of the emission intensities on the excitation power as compared to the YAG:Nd³⁺ crystallites embedded into the submicron SiO₂ spheres. The results suggest that silica spheres/YAG:Nd³⁺ composites are expected to be good hosts for microlaser systems.     

含10mol%氧化硅的钙磷酸盐玻璃陶瓷的合成及其体外生物活性

采用高分子网络凝胶法合成出SiO2-CaO-P2O5生物玻璃陶瓷,该材料具有较低含硅量和高钙磷比(nCa/nP=1.57)的特点,更接近人体硬组织的成分。将材料在SBF溶液浸泡研究材料的体外生物活性,通过TG/DTA,XRD,FTIR和SEM等方法对粉体和浸泡后的样品表面进行表征,ICP-AES对SBF溶液中钙、磷、硅离子的浓度进行检测。结果表明,氧化硅的添加有利于玻璃陶瓷表面磷灰石晶相的形成;随着浸泡时间的延长,沉积在样品表面的碳酸羟基磷灰石层逐渐由球型突起变为叶片状,溶液中钙、磷离子浓度降低,而硅离子浓度增加,说明材料具有良好的生物活性,适宜作为牙齿和骨骼的替代或修复材料。     

Investigation of New Ion-Conducting ORMOLYTES: Structure and Properties

Two families of hybrid organic-inorganic composites exhibiting Li⁺ ionic conduction (ORMOLYTES) have been prepared by the sol-gel process. The first family, prepared from a mixture of 3-isocyanatopropyltriethoxysilane, O,O Bis (2-aminopropyl)-polyethyleneglycol (or O,O Bis (2-aminopropyl)-polypropyleneglycol) and lithium salt, presents chemical bonds between the organic and the inorganic phase and an ionic conductivity higher than 10^-4 S m^-1 at room temperature. Their properties have been related to their structure using liquid state NMR measurements of ⁷Li between -100°C and +100°C and the DMTA technique. In the second family, prepared by ultrasonic method from a mixture of tetraethoxysilane (TEOS), polyethyleneglycol (PEG) and lithium salt, the organic and inorganic phases are not chemically bonded. Ionic conductivity has been studied as a function of the polymer chain length and concentration. Values of up to 10^-2 S m^-1 at room temperature have been obtained (with a silica-PEG₃₀₀ system, PEG/TEOS = 40% in weight). Again, structure was investigated by liquid state ⁷Li NMR measurements.     

Effects of pH and Dye Concentration on the Optical and Structural Properties of Coumarin-4 Dye-Doped SiO2-PDMS Xerogels

Optical and structural properties of coumarin-4 dye-doped SiO₂-PDMS xerogels synthesized by acid catalyzed (one-step) and acid-base catalyzed (two-step) sol-gel routes with varying pH (0.6 to 7) and dye content ( 5 × 10^–4 to 5 × 10^–2 mole) are reported. Spectroscopic methods such as photo-luminescence, FT-IR and FT-Raman were used for characterizations. The acid catalyzed xerogels prepared with pH < 2.5 exhibited two fluorescence peaks, I at 390 nm and II at 480 nm. The acid-base catalyzed xerogels synthesized with pH < 2.5 also exhibited two peaks, I at 400 nm and II at 475 nm. Peak II was not observed for the samples with pH 2.5. This phenomenon was attributed to the existence of pH dependent different forms of coumarin-4 molecule. The concentration-quenching phenomenon was observed for the acid catalyzed xerogels prepared with different dye concentration. TheFT-IR spectra indicated the existence of hydrogen bonds between the carbonyl groups of dye molecules and the silanol groups of gel matrix. The hydrogen bonding was the highest for the samples with the extremity pH, 0.6 and 7, resulting in the highest dye/gel matrix interactions, hence, the highest fluorescence peaks. The Raman studies indicated that the samples prepared with pH < 2.5 possessed relatively more number of 3-membered siloxane rings than 4-membered siloxane rings. The ring statistics was reversed for the samples with pH > 2.5. The number of silanol groups was higher for the samples with pH > 2.5.     

镁热还原气相法白炭黑制备纳米硅及其电化学性能

以气相法白炭黑(FS)为Si前驱体,通过镁热还原工艺和对获得的NPs-Si进行SiOx和C复合包覆,制备出NPs-Si@SiOx@C纳米复合结构,将其用作锂电池负极进行电化学性能测试。研究结果表明:镁热还原过程分两步进行,即SiO_2与Mg先生成Mg2Si中间相,Mg2Si继续与SiO_2反应生成Si的反应路径;根据此规律镁热还原气相法白炭黑的Si转化率达87.9%。电化学性能测试中NPs-Si@SiOx@C负极在2.0 A·g-1的电流密度下有1 300 mAh·g-1的容量平台,1 000次循环后的放电比容量为964.2mAh·g-1,容量保持率达75%。     

pH‐Disintegrable Polyelectrolyte Multilayer‐Coated Mesoporous Silica Nanoparticles Exhibiting Triggered Co‐Release of Cisplatin and Model Drug Molecules

We report on the fabrication of pH‐disintegrable polyelectrolyte multilayer‐coated mesoporous silica nanoparticles (MSN) capable of triggered co‐release of cisplatin and model drug molecules. The outer polyelectrolyte multilayer was assembled from permanently cationic polyelectrolyte, poly(allyl amine hydrochloride) (PAH), and negatively charged polyelectrolyte, P(DMA‐co‐TPAMA), consisting of N,N‐dimethylacrylamide (DMA) and 3,4,5,6‐tetrahydrophthalic anhydride‐functionalized N‐(3‐aminopropyl)methacrylamide (TPAMA) monomer units, which exhibits pH‐induced charge conversion characteristics. Thus, the subtle alteration of solution pH from 7.4 to ≈5–6 can lead to the disintegration of outer polyelectrolyte multilayers, accompanied with the co‐release of cisplatin and RhB.

     

Preparation and Characterization of Porous Silica Films by a Modified Base-Catalyzed Sol-Gel Process Containing PVA: I. The Precursor Solution Synthesis

A novel modified base-catalyzed Sol-Gel process containing polyvinyl alcohol (PVA) has been proposed to prepare the porous SiO₂ film. In this process, the growth of the sol particles was artificially broken off and controlled by acid-stabilising agent and PVA. As a result, a uniform and stable precursor solution was obtained in which the size of sol particles was stable. This new process efficiently overcomes the shortcomings of the traditional base-catalysed Sol-Gel process and can be employed to prepare porous SiO₂ films with desired porosity and thickness. The influence of the catalyst, the reaction temperature, the pH value, the stabilizing agent and the PVA additive on the size of the SiO₂ sol particles is systematically studied in part I.     

钴掺杂二氧化硅膜的制备、表征及氢气分离性能

采用正硅酸乙酯(TEOS)和Co(NO3)2.6H2O为前驱体通过溶胶-凝胶法制备掺钴微孔二氧化硅膜,研究钴在二氧化硅膜材料中的存在状态、膜材料孔结构以及膜材料的气体渗透和分离性能。结果表明钴元素以Si-O-Co的形式存在于SiO2骨架之中,掺杂Co 10%的微孔SiO2膜具有典型的微孔结构,其孔体积为0.119 cm3·g-1,平均孔径在0.52 nm左右且孔径主要分布在0.4～0.55 nm之间。氢气在膜材料中的输运低温下遵循Knudsen扩散机理,高于100℃时遵循活化扩散机理,300℃时膜材料的H2渗透率达到6.41×10-7 mol.m-2.s-1.Pa-1,H2/CO2分离系数达到6.61,高于Knudsen扩散的理想分离系数。     

基于MCM-41负载联吡啶钌的电致化学发光传感器

利用静电吸附作用将联吡啶钌[Ru(bpy)₃²⁺]负载到巯基化MCM-41介孔二氧化硅纳米颗粒上, 通过金-巯键修饰法将负载后的MCM-41固定在金电极表面, 发展了一种基于MCM-41负载联吡啶钌的电致化学发光传感器, 并研究了其电化学及电致化学发光行为. 基于三聚氰胺与增敏剂三正丙胺氨基结构的相似性, 将负载Ru(bpy)₃²⁺的MCM-41电致化学发光传感器用于三聚氰胺的检测, 获得了良好的检测效果, 为检测三聚氰胺提供了一种快速、简便的方法. 同时, 该研究为Ru(bpy)₃²⁺在电极表面的固定化提供了新思路.     

Investigations on the Angle-Dependent Dip Coating Technique (ADDC) for the Production of Optical Filters

Angle-dependent dip coating (ADDC) is a modified dip coating technique that offers advantages for the production of optical interference filters. In contrast to conventional dip coating (DC), the substrate is withdrawn from the coating solution under an angle of inclination. Thereby, the two surfaces of the substrate are coated with individual film thicknesses. An experimental setup for ADDC has been built and the decisive process influences on coating thicknesses have been evaluated. In order to gain full control over the individual layer thicknesses, reaching from 20 nm to 160 nm, it is necessary to vary the following process parameters: lifting speed, angle of inclination and concentration of the dipping solution. The results of coating experiments prove the advantages of ADDC over DC. A first example aims at reducing the number of coating steps: an ADDC long pass filter produced in 10 coating steps reaches the same optical performance as a conventional DC filter made in 16 steps. A second example demonstrates the possibility to improve quality: a commercial DC beam splitter can be improved with respect to the flatness of transmission and reflection curves when being produced in 4 steps by ADDC instead of 8 steps by DC. Furthermore, ADDC offers the possibility to fabricate even narrow band pass filters, which are naturally difficult to obtain by conventional DC.