多孔磁性硅胶微球的制备及其在基因组脱氧核糖核酸提取中的应用

采用模板法制备了多孔磁性硅胶微球,用于生物样品中基因组脱氧核糖核酸(DNA)的分离纯化。以球形和无定型硅胶为对照,考察了吸附液组成和洗脱时间等实验参数对小牛胸腺基因组DNA在磁性硅胶固相载体上的提取回收率的影响。实验结果表明:20%(W/V)聚乙二醇和2 mol/L氯化钠,洗脱10 m in,DNA的回收率可达80%;采用简单的细胞裂解体系和合适的吸附液组成,磁性微球应用于酿酒酵母中基因组DNA的提取,得到了平均长度约为5 kb、A260/A280大于1.77的高纯度DNA片段。     

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.     

A sol-gel immobilization of nano and micron size sorbents in poly(dimethylsiloxane) (PDMS) microchannels for microscale solid phase extraction (SPE)

Sorbent particles consisting of nano and micro silica, and micron size octadecylsilica (ODS) were immobilized using sol-gel chemistry onto poly(dimethylsiloxane) (PDMS) microfluidic channels to serve as μ-chip solid phase extraction (SPE) devices. Extraction, preconcentration and purification of biological and chemical analytes were carried out using these. Micro and nano scale silica-immobilized μ-SPE were used for the extraction/purification of DNA from recombinant Escherichia coli crude lysate. The average DNA recovery was 77 ± 9% (X ± R.S.D.) for the micron size silica particles and 70 ± 5% (X ± R.S.D.) for the nano silica particles. The extracted DNA could be amplified by polymerase chain reaction (PCR) whereas the DNA from the crude lysate solution could not be. This was a testimony to the purification capability of the μ-SPE device. ODS immobilized μ-SPE were used to study the extraction efficiency (EE) and enhancement factor (EF) for three groups of organic compounds, aromatics, phenols and carboxylic acids. They showed poor recovery and low enrichment because the analytes sorbed into the PDMS and were not quantitatively extracted.     

Needle-like calcium carbonate assisted self-assembly of mesostructured hollow silica nanotubes

Mesostructured hollow silica nanotubes (MHSNTs) were successfully produced via the self-assembly of C₁₆TMABr and silica species on the surface of needle-like calcium carbonate nanoparticles in an alkaline medium at room temperature. The characterization of MHSNTs by transmission electron microscopy (TEM), scanning electron microscopy (SEM), pore size distribution (PSD) and Brunauer-Emmett-Teller (BET) indicated that MHSNTs had uniform tubular hollow structures with big openings, a length of 1.5-2.0 μm, an inner diameter of 150-200 nm at the open end and 50-60 nm at the closed end, and a wall thickness of 20-30 nm, as well as a narrow PSD around 2.3 nm in the shells and a BET surface area as high as ∼975.3 m²/g. By small-angle X-ray diffraction (XRD), BET and pore structure analysis, it was found that more uniformly structured mesopores could be formed by the method of removing the double templates simultaneously through a solvent extraction process, as compared to the separate removal of the double templates by calcinating and then etching in an acidic solution, and the amount of C₁₆TMABr affected the mesoporous structures of MHSNTs greatly. The formation processes of MHSNTs were also studied with XRD and FTIR.     

A simple route to synthesize nanocrystalline nickel ferrite (NiFe2O4) in the presence of octanoic acid as a surfactant

Nanocrystalline nickel ferrite (NiFe₂O₄) powder was prepared by a co-precipitation method from Ni and Fe chlorides. The as-prepared samples were characterized by powder X-ray diffractometry (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and vibrating sample magnetometry (VSM). SEM and TEM indicated that the particles were spherical with particle sizes in the range 25 ± 5 nm. The magnetic properties of the sample were measured by using a vibrating sample magnetometer, which showed that the sample exhibited typical ferromagnetic behavior at room temperature, while a finite coercivity of 245.5 Oe was present at 300 K. The saturation magnetization of the sample (23.13 emu/g) was significantly lower than that for the reported multidomain bulk particles (55 emu/g), reflecting the ultrafine nature of the sample.     

Preparation of uniform rhodamine B-doped SiO2/TiO2 composite microspheres

Uniform rhodamine B (RB)-doped SiO₂/TiO₂ composite microspheres with catalytic and fluorescent properties were prepared by an easy and economical method in this paper. The composite microspheres were built up with well-dispersed silica particles as the cores, RB as both the doped agent and stabilizer, and the TiO₂ shells were obtained through the hydrolysis of TiCl₄ in water bath. The morphology and structure of the particles were characterized by scanning electron microscopy (SEM) and X-ray powder diffraction (XRD). The characterization results indicate that composite particles are all in spherical shape and have a narrow size distribution. The composite particles calcined above 500 °C reveal clear crystalline reflection peaks of the rutile TiO₂ which exhibits well catalytic property. The photocatalytic experiment was carried out in order to examine the catalytic property of composite microspheres. The fluorescent property of particles was also investigated. Dye-leakage test indicates that RB molecules entrapped in the composite particles by this method are stable inside the particles.     

Extraction of cationic surfactant templates from mesoporous materials by CH(3)OH-modified CO(2) supercritical fluid

Extraction of cationic surfactant templates from MCM-41, MCM-48, SBA-1 and SBA-3 has been conducted using CH₃OH-modified CO₂ supercritical fluid. The supercritical fluid extraction (SFE) has been integrated with thermogravimetry (TG), X-ray diffraction (XRD) and N₂ adsorption-desorption to evaluate extraction efficiency and structural stability of mesoporous materials. Experiments of optimization indicate that the conditions of 90 bar, 85 °C, CH₃OH/CO₂ = 0.1/1.0 ml/min and 3 h are most suitable for the SFE of cationic templates. 76-95% of the cationic templates can be extracted from the mesoporous materials. XRD and N₂ adsorption-desorption studies illustrate that SFE possesses some advantages over calcination in maintaining mesoporous uniformity and structural stability when used to remove templates. The impact of curing on mesoporous structure is also dealt with.     

Magnetic Silica‐Coated Sub‐Microspheres with Immobilized Metal Ions for the Selective Removal of Bovine Hemoglobin from Bovine Blood

Magnetic silica‐coated magnetite (Fe₃O₄) sub‐microspheres with immobilized metal‐affinity ligands are prepared for protein adsorption. First, magnetite sub‐microspheres were synthesized by a hydrothermal method. Then silica was coated on the surface of Fe₃O₄ particles using a sol–gel method to obtain magnetic silica sub‐microspheres with core‐shell morphology. Next, the trichloro(4‐chloromethylphenyl) silane was immobilized on them, reacted with iminodiacetic acid (IDA), and charged with Cu²⁺. The obtained magnetic silica sub‐microspheres with immobilized Cu²⁺ were applied for the absorption of bovine hemoglobin (BHb) and the removal of BHb from bovine blood. The size, morphology, and magnetic properties of the resulting magnetic micro(nano) spheres were investigated by using scanning microscopy (SEM), transmission electron microscopy (TEM), X‐ray diffraction (XRD), and a vibrating sample magnetometer (VSM). The measurements showed that the magnetic sub‐microspheres are spherical in shape, very uniform in size with a core‐shell, and are almost superparamagnetic. The saturation magnetization of silica‐coated magnetite (Fe₃O₄) sub‐microspheres reached about 33 emu g^?1. Protein adsorption results showed that the sub‐microspheres had a high adsorption capacity for BHb (418.6 mg g^?1), low nonspecific adsorption, and good removal of BHb from bovine blood. This opens a novel route for future applications in removing abundant proteins in proteomic analysis.     

Imprinted functionalized silica sol-gel for solid-phase extraction of triazolamin

A triazolam-imprinted silica microsphere was prepared by combining a surface molecular-imprinting technique with the sol-gel process. The results illustrate that the triazolam-imprinted silica microspheres provided using γ-aminopropyltriethoxysilane and phenyltrimethoxysilane as monomers exhibited higher selectivity than those provided from γ-aminopropyltriethoxysilane and methyltriethoxysilane. In addition, the optimum affinity occurred when the molar ratio of γ-aminopropyltriethoxysilane, phenyltrimethoxysilane, and the template molecule was 4.2:4.7:0.6. Retention factor (k) and imprinting factor (IF) of triazolam on the imprinted and non-imprinted silica microsphere columns were characterized using high performance liquid chromatography (HPLC) with different mobile phases including methanol, acetonitrile, and water solutions. The molecular selectivity of the imprinted silica microspheres was also evaluated for triazolam and its analogue compounds in various mobile phases. The better results indicated that k and IF of triazolam on the imprinted silica microsphere column were 2.1 and 35, respectively, when using methanol/water (1/1, v/v) as the mobile phase. Finally, the imprinted silica was applied as a sorbent in solid-phase extraction (SPE), to selectively extract triazolam and its metabolite, α-hydroxytriazolam, from human urine samples. The limits of detection (LOD) for triazolam and α-hydroxytriazolam in urine samples were 30 ± 0.21 ng mL⁻¹ and 33 ± 0.26 ng mL⁻¹, respectively.     

pH-responsive deoxyribonucleic acid capture/release by polydopamine functionalized magnetic nanoparticles

Polydopamine functionalized magnetic nanoparticles (PDA@Fe₃O₄) were prepared and characterized by transmission electron microscopy, scanning electron microscopy, zeta potential and vibrating sample magnetometry. They were found to enable highly efficient capture of genomic deoxyribonucleic acid (DNA). The adsorption capacity of PDA@Fe₃O₄ for genomic DNA can reach 161 mg g⁻¹. The extraction protocol used aqueous solutions for DNA binding to and releasing from the surface of the magnetic particles based on the pH inducing the charge switch of amino and phenolic hydroxyl groups on PDA@Fe₃O₄. The extracted DNA with high quality (A₂₆₀/A₂₈₀ = 1.80) can be directly used as templates for polymerase chain reaction (PCR) followed by capillary electrophoresis (CE) analysis. None of the toxic chemical reagents and PCR inhibitors was used throughout the whole procedure. PDA@Fe₃O₄ based magnetic solid phase extraction (MSPE) method was superior to those using commercial kit and traditional phenol–chloroform extraction methods in yield of DNA. The developed PDA@Fe₃O₄ based MSPE-PCR-CE method was applied for simultaneous and fast detection of Listeria monocytogenes and Escherichia coli O157:H7 in milk.     

Fabrication of hollow silica microspheres utilizing a hydrothermal approach

Hollow silica microspheres(HSMSs) have been successfully fabricated via a facile hydrothermal route using D-glucose as the sacrificial template and sodium silicate powder as the silica precursor.The resulting silica hollow particles were characterized by scanning electron microscopy(SEM),transmission electron microscopy(TEM),X-ray diffraction(XRD),and infrared spectroscopy(IR).The surface area was determined using the BET method.SEM and TEM images exhibited micro-sized silica hollow particles with a size of ~1.5μm.     

N-Methylimidazolium modified magnetic particles as adsorbents for solid phase extraction of genomic deoxyribonucleic acid from genetically modified soybeans

N-Methylimidazolium modified magnetic particles (MIm-MPs) were prepared and applied in the solid phase extraction of genomic deoxyribonucleic acid (DNA) from genetically modified soybeans. The adsorption of MIm-MPs for DNA mainly resulted from the strong electrostatic interaction between the positively charged MPs and the negatively charged DNA. The elution of DNA from MPs–DNA conjugates using phosphate buffer resulted from the stronger electrostatic interaction of phosphate ions with MPs than DNA. In the extraction procedure, no harmful reagents (e.g. phenol, chloroform and isopropanol, etc.) used, high yield (10.4 μg DNA per 30 mg sample) and high quality (A₂₆₀/A₂₈₀ = 1.82) of DNA can be realized. The as-prepared DNA was used as template for duplex-polymerase chain reaction (PCR) and the PCR products were analyzed by a sieving capillary electrophoresis method. Quick and high quality extraction of DNA template, and fast and high resolution detection of duplex PCR products can be realized using the developed method. No toxic reagents are used throughout the method.     

陶瓷基钛掺杂硅胶块体吸附剂研究

以陶瓷纤维纸为基材, 顺次经水玻璃、酸性硫酸氧钛溶液浸渍共沉淀制得新型蜂窝状陶瓷基钛掺杂硅胶块体吸附剂. FTIR谱在波数954 cm^－1附近的特征吸收峰表明钛掺杂硅胶中存在Si-O-Ti键; XRD谱显示掺杂材料为无定型非晶相材料; SEM显示钛掺杂硅胶粒子较好地分散在陶瓷纤维表面及其空隙中; 用EDS及XPS揭示了材料的组成和钛原子含量, 根据钛掺杂前后XPS中Si2p, O1s, Ti2p 3/2电子结合能变化以及²⁹Si MAS NMR中硅原子化学位移差异, 进一步表明钛原子替代硅原子进入了四面体骨架; BET分析显示掺杂材料以中孔为主. 与硅胶相比, 由于钛掺杂, 其比表面积、孔容增大, 吸附性能、耐热性能增强.     

Size characterization by Sedimentation Field Flow Fractionation of silica particles used as food additives

Four types of SiO₂, available on the market as additives in food and personal care products, were size characterized using Sedimentation Field Flow Fractionation (SdFFF), SEM, TEM and Photon Correlation Spectroscopy (PCS). The synergic use of the different analytical techniques made it possible, for some samples, to confirm the presence of primary nanoparticles (10 nm) organized in clusters or aggregates of different dimension and, for others, to discover that the available information is incomplete, particularly that regarding the presence of small particles. A protocol to extract the silica particles from a simple food matrix was set up, enriching (0.25%, w w⁻¹) a nearly silica-free instant barley coffee powder with a known SiO₂ sample. The SdFFF technique, in conjunction with SEM observations, made it possible to identify the added SiO₂ particles and verify the new particle size distribution. The SiO₂ content of different powdered foodstuffs was determined by graphite furnace atomic absorption spectroscopy (GFAAS); the concentrations ranged between 0.006 and 0.35% (w w⁻¹). The protocol to isolate the silica particles was so applied to the most SiO₂-rich commercial products and the derived suspensions were separated by SdFFF; SEM and TEM observations supported the size analyses while GFAAS determinations on collected fractions permitted element identification.     

Fabrication of Porous Silica Microspheres Under the Assistance of Solid Template

Spherical porous silica microparticles were synthesized by a sol-gel process in the presence of porous CaCO₃ particles, followed by removal of the carbonate templates. The resulting silica particles had very high porosity and wide pore size distribution, whose surface area and pore volume reached up to 367.3 m²/g and 0.72 mL/g, respectively. With a larger amount of the tetraethyl orthosilicate used, hollow silica microspheres were further obtained. Characterization was made to confirm the chemical and physical structures and purity of the silica microspheres. Spontaneous deposition of tetramethyl rhodamine isothiocyanate labeled dextran into the microspheres was also observed due to the charge attraction.     

Zirconia layer coated mesoporous silica microspheres used for highly specific phosphopeptide enrichment

Zirconia layer coated mesoporous silica microspheres with mesostructured cellular foams (MCFs) were prepared by NH₃/water vapor-induced internal hydrolysis method. Zirconia layer coated MCF microspheres were characterized by SEM, XRD, N₂ sorption, UV, and chromatographic analysis, and explored for enrichment of phosphopeptides. ZrO₂/MCF microspheres in solid-phase extraction (SPE) mode demonstrated much higher selectivity and higher efficiency towards phosphopeptide enrichment than bulk ZrO₂ particles. In particular, the selectivities of ZrO₂/MCF microspheres towards multi-phosphopeptides are even higher than that of the widely used commercial TiO₂ microparticles. The ZrO₂/MCF microspheres were also applied to enrich endogenous phosphopeptides from human serum, and twelve endogenous phosphorylated peptides could be specifically enriched.     

Polystyrene-ZnO core-shell microspheres and hollow ZnO structures synthesized with the sulfonated polystyrene templates

Mono-sized sulfonated polystyrene (PS) microspheres were used as templates to prepare PS-zinc oxide (ZnO) core-shell microspheres. Two different hollow ZnO structures were obtained after removing the PS cores by solvent extraction or calcinations. However, we obtained rod-like ZnO by either using unsulfonated PS microspheres as templates or without any templates. Transmission electron microscope (TEM) and scanning electron microscope (SEM) images were used to characterize the structures and morphologies of all the samples. X-ray diffraction (XRD), electron diffraction (ED) and infrared (IR) spectra were, respectively, used to study the crystal structure and composition of samples, respectively.     

磁性二氧化硅微球的表面修饰及其在植物基因组核酸纯化中的应用

在利用自主研发的专利技术制备球形磁性硅胶微球的基础上,对磁性硅胶微球进行表面改性,使其表面分别键合硅羟基、环氧基、邻二醇基和羧基等官能团,并对表面官能团进行了定量研究。以小牛胸腺基因组脱氧核糖核酸(DNA)为模型化合物,研究了核酸在不同表面官能团的磁性硅胶上的吸附和脱附行为,发现表面具有硅醇基的磁球对DNA的回收率最高。将改性后磁性微球应用于玉米DNA的提取,得到了平均长度大于8kb的高纯度基因组DNA。与传统的有机溶剂抽提法相比,基于磁性微球的核酸固相萃取法具有快速简便、省时省力、易于自动化的特点,适合于大规模植物基因组DNA的样品制备。     

Development of a simultaneous extraction and cleanup method for pyrethroid pesticides from indoor house dust samples

An efficient and reliable analytical method was developed for the sensitive and selective quantification of pyrethroid pesticides (PYRs) in house dust samples. The method is based on selective pressurized liquid extraction (SPLE) of the dust-bound PYRs into dichloromethane (DCM) with analysis by gas chromatography/mass spectrometry. Various adsorbents and combinations of extraction solvents and temperatures were evaluated to achieve a high-throughput sample preparation that eliminates the post-extraction cleanup step. The final method used sulfuric acid-impregnated silica (acid silica) and neutral silica together in the extraction cell with the dust sample to provide both extraction and cleanup simultaneously. The optimal ratio of dust/acid silica/silica was 1:0.8:8. The extraction was performed at 2000 psi, at 100 °C with DCM for 5 min in three cycles. Method precision and accuracy were evaluated by the analysis of triplicate aliquots of the dust samples and the samples fortified with the target PYRs. The accuracy measured as the recoveries of the PYRs in the fortified samples ranged from 85% to 120%. The precision measured as the relative standard deviation of replicate samples was within ±25%. The SPLE method was applied to 20 house dust samples collected from households that participated in two field studies regarding exposures to pesticides and other pollutants. Similar concentrations of target PYRs were obtained for the SPLE and a stepwise extraction/cleanup procedure. The SPLE procedure reduces organic solvent consumption and increases the sample throughput when compared with a traditional stepwise extraction and cleanup procedure. This study demonstrates that the SPLE procedure can be applied to complex dust matrices for analysis of PYRs for large scale exposure or environmental monitoring studies.     

ZnO@P(AA/MMA/GMA)@Fe3O4复合微球：制备及光催化性能

采用导向沉淀法在胺化的P(AA/MMA/GMA)@Fe3O4(MCM,其中AA为丙烯酸,MMA为甲基丙烯酸甲酯,GMA为甲基丙烯酸缩水甘油酯)微球表面负载ZnO粒子制备得到了ZnO@P(AA/MMA/GMA)@Fe3O4(ZPM)三层结构磁性复合微球。通过XRD、SEM、粒度分析、TGA及VSM等手段对ZPM微球进行表征,结果表明:ZPM微球平均粒径为1.38μm,ZnO负载量为13.02%,比饱和磁化强度为8.64 emu.g-1。同时研究了ZPM微球的光催化性能,以罗丹明B(RhB)为被降解物,微球对RhB的吸附效率为50.07%,催化降解效率可达93.40%。