磁性SiO2纳米粒子的制备及其用于漆酶固定化

以氨基修饰的磁性SiO2纳米粒子为载体,通过交联剂戊二醛固定漆酶,对固定化条件进行了优化,比较了固定化酶与游离酶的酶学性质. 结果表明,漆酶固定化的最佳条件为戊二醛浓度8%(w),固定化时间6 h,缓冲液pH值7.0,初始酶液浓度0.15 g/L. 固定化的漆酶的最适pH为4.0,最适温度为20℃. 在60℃条件下保温4 h,固定化漆酶仍能保持酶活力60.9%,在连续10次操作后,酶活力仍能保持55%以上,其热稳定性和操作稳定性均比游离酶高.     

磁性介孔二氧化硅微球的研究及应用进展

磁性介孔二氧化硅微球作为一种新型纳米复合材料,广泛应用于众多领域.综述了近年来磁性介孔二氧化硅微球的制备方法,并对其在靶向药物、生物富集与分离、磁热疗、固定化酶等生化领域的应用作了介绍.     

荧光磁性双功能Fe3O4@PHEMA-Tb微球的制备及其蛋白固定化

以甲基丙烯酸-2-羟基乙酯为单体,N,N￠-亚甲基双丙烯酰胺为交联剂,采用光化学方法在Fe3O4磁性液体中制备了磁性聚甲基丙烯酸-2-羟基乙酯微球,合成了含有稀土元素Tb的荧光磁性高分子微球,以牛血清白蛋白为模型对微球固定释放蛋白能力进行了研究,用VSM, PCS, FT-IR, TG-DTA, SEM, FS, UV-Vis等技术对微球的性能进行了表征. 结果表明,荧光磁性高分子微球粒径为29.6 nm,比饱和磁化强度为40.1 emu/g,变异系数为3.7%,具有超顺磁性荧光性,分散性好,呈圆球形,对蛋白的装载率和包封率分别为6.5%和74.7%,pH越低蛋白释放率越高.     

均匀包覆的Fe3O4@SiO2纳米复合粒子的制备

本文主要分析了超顺磁性Fe3O4@SiO2纳米复合粒子的化学制备方法,并简要分析了其作为催化载体在催化剂分离方面的应用前景.通过各种制备方法的比较,认为经由稳定的磁性Fe3O4液体(或称Fe3O4磁流体)是制备均匀包覆的Fe3O4@SiO2样品的比较理想的路线.     

磁性Fe3O4@SiO2颗粒结构对其吸附DNA的影响

采用共沉淀法和水热法制备了不同结构的超顺磁性Fe3O4@SiO2纳米颗粒,对其进行表征,研究了其吸附DNA的性能及磁分离性能. 结果表明,20?750 nm范围内粒径较大的颗粒与DNA结合时可提供更多单位平面结合位点,使结合的稳定性和结合几率增加,DNA结合量提高. 不同核?壳结构的Fe3O4@SiO2纳米颗粒的磁分离响应时间不同,内核大小相近时,壳层厚度增加会导致颗粒在磁场中受到的磁力与阻力的比值减小,磁响应时间增加,DNA回收率降低. 粒径约为200 nm的Fe3O4@SiO2纳米颗粒用于纯化全血中DNA最好,提取率为95.2%,磁响应时间为10 s.     

多巴胺包埋磁性SiO2固定化漆酶催化去除4-氯酚

以磁性纳米颗粒为载体,通过多巴胺(dopamine,DA)聚合原位包埋制备了磁性SiO₂固定化漆酶(Fe₃O₄@SiO₂-PDA-Lac)。结果显示纳米颗粒尺寸均匀,并且保持较高的饱和磁性。通过最优条件制备出的固定化漆酶在50℃放置6 h后,活性保持在63%,而游离酶仅保留18%。将固定化酶用于催化降解4-氯酚(4-CP),探究了溶液pH、漆酶浓度和ABTS[2,2-联氮-二(3-乙基-苯并噻唑-6-磺酸铵)]对4-CP去除率的影响。固定化漆酶在反应最适pH时,4-CP去除率为84.3%,而游离酶仅为65.7%。当漆酶浓度为1.2 U·ml^-1时,反应8 h后,4-CP去除率可达95%,而游离酶的4-CP去除率仅82%。ABTS可促进固定化漆酶降解4-CP,当体系中加入50 μmol·L^-1 的ABTS,反应10 min后,固定化酶对4-CP去除率可达99%。固定化漆酶在重复使用10次后,4-CP去除率仍可达67%。     

核/壳结构磁性Fe3O4@SiO2纳米粒子的制备及表征

在Triton X-100/正己醇/环己烷/水反相微乳液体系中,分别采用一步法和两步法制备具有核/壳结构的磁性Fe3O4@SiO2复合纳米粒子.考察了搅拌方式和超声条件对一步法产物结构、形貌的影响,并与两步法进行了对比研究.通过XRD、FT-IR、DLS、TEM和VSM对复合颗粒进行了表征.结果表明,反相微乳液体系下,...     

近单分散介孔SiO2/Fe3O4/SiO2微球的制备及漆酶固定化

以自制近单分散、平均粒径约为250 nm的SiO2亚微球为核心,采用液相沉积法得到β-FeOOH/SiO2微球,再通过溶胶-凝胶法以β-FeOOH/SiO2微球为内核,十六烷基三甲基溴化铵(CTAB)为模板剂,正硅酸乙酯(TEOS)为硅源,经水解缩聚反应,焙烧后得到近单分散介孔SiO2/Fe3O4/SiO2微球,以复合微球为载体,对漆酶进行固定。结果表明,近单分散介孔SiO2/Fe3O4/SiO2复合微球的介孔层厚约40 nm,具有较大的饱和磁化强度(14.715 emu/g),较小的剩余矫顽力(约为109Oe),其比表面积为391.067 m2/g,孔容为0.53 cm3/g,孔径分别在5.43 nm和20～80 nm,呈现双孔径分布。复合微球吸附漆酶后,介孔材料的比表面积与孔容分别减小为103 m2/g和0.37 cm3/g,复合微球对漆酶的吸附量为202.6 mg/g。     

纳米磁性空心微球制备技术研究进展

纳米磁性空心微球由于其独特的结构和性质在国内外引起了越来越多的关注。本文综述了纳米磁性空心微球制备方法的最新研究进展。制备方法一般可分为模板法、非模板法、牺牲模板法、自催化还原法、置换反应法、溶胶-凝胶烧结法和化学镀法。同时,讨论了各种制备方法存在的问题及其优缺点。     

表面改性磁性Fe3O4/SiO2复合微球的制备与表征

以聚乙二醇修饰的纳米Fe3O4为种子,采用溶胶-凝胶法使正硅酸乙酯在氨水催化下进行水解、缩合反应,在Fe3O4表面包覆一层SiO2,制备了磁性Fe3O4/SiO2复合微球.复合微球粒径均一,而且具有良好的超顺磁性,饱和磁化强度Ms达31.98 A·m2/kg.最后用γ-甲基丙烯酰氧基丙基三甲氧基硅烷对Fe3O4/SiO...     

磁性能优化纳米Fe3O4合成工艺

通过化学共沉淀法制备了纳米Fe3O4粉体,研究了反应物配比和反应温度对磁性粒子的物相以及磁性能的影响,优化了合成工艺。通过对二元参数的选择和严格控制,可以制备出磁化率高、粒径分布相对较好的球形磁性颗粒,干燥后获得纳米磁性粉体。     

SiO2@BiOCl-Bi24O31Cl10核壳微球的合成及光催化

调整禁带宽度和抑制光生电子-空穴对复合是提高Bi₂O₃半导体光催化性能的重要途径。首先采用溶液合成和热处理法成功制备了SiO₂@Bi₂O₃核壳微球,研究了投料比、热处理温度等因素来调控核壳组成和包覆效果。为提高光催化活性,采用Cl掺杂改变SiO₂@Bi₂O₃核壳微球壳层的结构、形貌与组成,通过XRD、SEM、TEM等方法确定了微球壳层为BiOCl-Bi₂₄O₃₁Cl₁₀复合物。调整摩尔比、氨水和NaCl用量等参数,优化SiO₂@BiOCl-Bi₂₄O₃₁Cl₁₀核壳微球的均匀包覆效果,大幅提高了对罗丹明B（RhB）的光催化降解效率。在此基础上,阐述了SiO₂@Bi₂O₃核壳微球的形成机理和SiO₂@BiOCl-Bi₂₄O₃₁Cl₁₀核壳微球的光催化降解机理。     

SiO2@BiOCl-Bi24O31Cl10核壳微球的合成及光催化

调整禁带宽度和抑制光生电子-空穴对复合是提高Bi₂O₃半导体光催化性能的重要途径。首先采用溶液合成和热处理法成功制备了SiO₂@Bi₂O₃核壳微球,研究了投料比、热处理温度等因素来调控核壳组成和包覆效果。为提高光催化活性,采用Cl掺杂改变SiO₂@Bi₂O₃核壳微球壳层的结构、形貌与组成,通过XRD、SEM、TEM等方法确定了微球壳层为BiOCl-Bi₂₄O₃₁Cl₁₀复合物。调整摩尔比、氨水和NaCl用量等参数,优化SiO₂@BiOCl-Bi₂₄O₃₁Cl₁₀核壳微球的均匀包覆效果,大幅提高了对罗丹明B（RhB）的光催化降解效率。在此基础上,阐述了SiO₂@Bi₂O₃核壳微球的形成机理和SiO₂@BiOCl-Bi₂₄O₃₁Cl₁₀核壳微球的光催化降解机理。     

Synthesis of multifunctional hollow SiO2-CaO-Fe2O3 glass-ceramic nanospheres

Glass ceramics with multifunctions of bioactivity, drug delivery, and magnetic hyperthermia have great potential applications in the field of bioscience. Herein, we design and synthesize a multifunctional hollow SiO₂-CaO-Fe₂O₃ (SCF) glass-ceramic nanosphere (GCNS) by a template-mediated sol-gel precipitate method. The magnetite as the main crystal phase was successfully precipitated from the SCF glassy matrixes after heat treated at 800°C. The influence of composition and the Fe³⁺/Fe²⁺ precursor ratio on the morphology, crystallization, micropore structure, and magnetic properties were systematically studied. Intact spherical hollow SCF GCNSs were obtained under the heat treatment at 800°C for 2 hours when the Fe₂O₃ content below 15 wt%. Under certain Fe₂O₃ content, the coercivity and micropore volume of SCF GCNSs were found to be increased with increasing the mole ratio of FeCl₃/FeCl₂ precursors. High drug loading capacity of 24.2 wt% and sustained drug release were observed from the methylene blue–loaded SCF GCNSs in simulated body fluid solution. The hollow SCF GCNSs synthesized in this work exhibiting good magnetic properties and sustained drug release performance have great potential applications in the cancer therapy.     

PLA–PEG‐grafted hollow magnetic silica microspheres as the carrier of iodinated contrast media

In this work, hollow magnetic silica microspheres (HMS) were synthesized by the template method, polyethylene glycol (PEG) and poly(lactic acid) (PLA)‐grafted hollow magnetic microspheres HMS@PLA–PEG were successfully prepared through ring‐opening polymerization method. Ioversol was loaded into HMS@PLA–PEG by physical coating, and the drug loading content was up to 39.4%. It also exhibited a slower and steady release than HMS and the cumulative release was up to 55.1% at physiological pH, which implied the PLA–PEG could prolong the circulation time. Meanwhile, to improve the efficiency of contrast, we have developed composite microspheres encapsulating superparamagnetic iron oxide (Fe₃O₄) as magnetic target for increasing the local concentration of the contrast media and expecting to put magnetic resonance imaging (MRI) and computed tomography (CT) technology together to apply in medical applications. Furthermore, the cytotoxicity assay in vitro was also investigated. The results revealed the ioversol‐loaded HMS@PLA–PEG exhibited low toxicity at a higher concentration, even it is up to 400 μg/mL. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44914.     

Synthesis of Fe3O4@SiO2@MPS@P4VP nanoparticles for nitrate removal from aqueous solutions

In this study, synthesis of Fe₃O₄@SiO₂@MPS@poly(4‐vinylpyridine) core‐shell‐shell structure was investigated as an efficient adsorbent for removal of nitrate ions from aqueous solutions. Fe₃O₄ nanoparticles were initially prepared by co‐precipitation method, then the surface of Fe₃O₄ was coated with SiO₂ through a modified St öber method. Finally, the Fe₃O₄@SiO₂ nanoparticles were modified by 3‐(trimethoxysilyl) propyl methacrylate followed by emulsion polymerization of 4‐vinylpyridine. The resultant material was acidified in HCl solution to be effective for nitrate removal. The synthesized sample was characterized by X‐ray diffraction, transmission electron microscopy, field‐emission scanning electron microscopy, Fourier‐transform infrared spectra, thermogravimetric analysis (TGA), and vibrating sample magnetometer. The removal efficiency was optimized for some experimental parameters such as pH, contact time, and amount of sorbent loading. The maximum predictable adsorption capacity was 80.6 (mg nitrate/g sorbent) at optimum conditions. Also, regeneration of the nitrate adsorbed particles was possible with NaOH solution. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44330.