Application of magnetic iron oxide nanoparticles prepared from microemulsions for protein purification

BACKGROUND: Magnetic nanoparticles are of immense interest for their applications in biotechnology. This paper reports the synthesis of magnetic iron oxide nanoparticles from two different water‐in‐oil microemulsion systems (ME‐MIONs), their characterization and also their use in purification of coagulant protein. RESULTS: ME‐MIONs have demonstrated to be an efficient binder in the purification of Moringa oleifera protein when compared with the superparamagnetic iron oxide nanoparticles prepared from coprecipitation in aqueous media. The size and morphology of the ME‐MIONs were studied by transmission electron microscopy (TEM) while the structural characteristics were studied by X‐ray diffraction (XRD). The microemulsion magnetic iron oxide nanoparticles (ME 1‐MION and ME 2‐MION) obtained have a size range 7–10 nm. The protein and ME‐MIONs interaction was investigated by Fourier transform infrared spectroscopy (FT‐IR); the presence of three peaks at 2970, 2910 and 2870 cm^?1 respectively, confirms the binding of the protein. The purification and molecular weight of the coagulant protein was 6.5 kDa as analyzed by SDS‐PAGE. CONCLUSION: The ME‐MIONs have the advantage of being easily tailored in size, are highly efficient as well as magnetic, cost effective and versatile; they are, thus, very suitable for use in a novel purification technique for protein or biomolecules that possess similar characteristics to the Moringa oleifera coagulant protein. Copyright © 2011 Society of Chemical Industry     

Facile method to synthesize magnetic iron oxides/TiO2 hybrid nanoparticles and their photodegradation application of methylene blue

The primary objective of this study is to investigate the effect of slip mechanisms in nanofluids through scaling analysis. The role of nanoparticle slip mechanisms in both water- and ethylene glycol-based nanofluids is analyzed by considering shape, size, concentration, and temperature of the nanoparticles. From the scaling analysis, it is found that all of the slip mechanisms are dominant in particles of cylindrical shape as compared to that of spherical and sheet particles. The magnitudes of slip mechanisms are found to be higher for particles of size between 10 and 80 nm. The Brownian force is found to dominate in smaller particles below 10 nm and also at smaller volume fraction. However, the drag force is found to dominate in smaller particles below 10 nm and at higher volume fraction. The effect of thermophoresis and Magnus forces is found to increase with the particle size and concentration. In terms of time scales, the Brownian and gravity forces act considerably over a longer duration than the other forces. For copper-water-based nanofluid, the effective contribution of slip mechanisms leads to a heat transfer augmentation which is approximately 36% over that of the base fluid. The drag and gravity forces tend to reduce the Nusselt number of the nanofluid while the other forces tend to enhance it.     

磁性纳米颗粒的功能化及其在DNA提取中的应用

提出了一种应用功能化的磁性纳米颗粒进行DNA提取的新方法．该方法首先通过3-氨丙基三乙氧基硅烷（APTES）在纳米颗粒表面修饰上氨基（-NH2）官能团,然后利用氨基化的磁性Fe3O4纳米粒子（NH2-MNPs）进行DNA提取。结果表明,利用100μgNH2-MNPs从200μL全血中提取的基因组DNA大于2．89μg,OD260／OD280比值介于1．78和1．82之间。     

BSA修饰Fe_3O_4纳米颗粒用于苦瓜提取液中活性成分的筛选

用一步法直接合成了表面氨基化修饰的Fe3O4纳米颗粒(NH2-MION),通过双功能团试剂戊二醛将牛血清白蛋白(BSA)固定在NH2-MION表面,将BSA-MION用于苦瓜提取液中活性成分的筛选,利用气相色谱-质谱联用技术鉴定出了3种与BSA作用较强的活性成分。     

Effect of iron oxide nanoparticles on the morphological properties of isotactic polypropylene

Isotactic polypropylene (iPP) and iron oxide (Fe₃O₄) nanocomposites were mixed by masterbatch blending technique in a single screw extruder machine. The concentrations of Fe₃O₄ in the iPP/Fe₃O₄ nanocomposites were 0.5, 1, 2, and 5% by weight. The influence of Fe₃O₄ nanoparticles on the effectiveness of nucleation, morphology, mode of crystallization, and crystallinity of iPP were studied by differential scanning calorimetry (DSC) and polarized light microscopy (PLM). The introduction of Fe₃O₄ nanoparticles in the iPP matrix inhibited the formation of β crystals, and caused a shift in the melting point to higher values. The magnitude of the shift was up to 20–21°C which indicates that using the masterbatch technique leads to an enhancement of the dispersion process of the Fe₃O₄ nanoparticle and the formation of less agglomerates in the iPP/Fe₃O₄ nanocomposites. The percentage crystallinity, X_c, increased at the low cooling rates of 1 and 2°C/min. At higher cooling rates of 5, 10, and 20°C/min, the masterbatch technique produced nanocomposites of X_c with nonuniform trends. The overall crystallization rate enhancement for the iPP/Fe₃O₄ nanocomposites is attributed to the presence of Fe₃O₄ nanoparticles as a nucleating agent which have no significant effect on the growth rate of iPP crystals. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

磁性磷脂酶D交联酶聚集体的制备及其酶学性质

以磁性Fe3O4为载体,采用吸附-聚集-交联的方法固定来源于Streptomyces chromofuscus的磷脂酶D （scPLD）。该方法制备的磁性磷脂酶D交联酶聚集体（MCLEA）酶活回收率可达72.89%,酶活为（437±6.60）U/g。与游离酶相比,MCLEA在不同温度和pH下的稳定性都得到了一定程度的提升,但由于与底物的亲和力降低,需要更高浓度的磷脂酰胆碱（PC）和Ca2+作为反应底物与MCLEA结合。另外,还研究了MCLEA的有机溶剂耐受性,发现乙醇、四氢呋喃、叔丁醇、乙酸乙酯、乙醚和甲苯等有机溶剂对MCLEA的酶促反应具有促进作用,此发现为scPLD催化转磷脂酰作用生成磷脂酰丝氨酸（PS）过程中构建双相体系时有机溶剂的选择提供了参考。MCLEA在进行连续13次酶促反应后,酶活仍可保留在76%以上,其半衰期为331.67 min,说明所选择的固定化方案可以提高酶的稳定性,从而提高其在催化反应过程中的重复利用性。     

Anomalous IR optical properties of aggregates of Pd nanoparticles induced through electrochemical cyclic voltammetry

IR optical properties of Pd nanoparticles with different size and aggregation state were studied in the current paper. The dispersed Pd nanoparticles () stabilized with poly(N-vinylpyrrolidone) (PVP) were synthesized by the seeding growth method, in which the seeds were formed step by step through reducing H₂PdCl₄ with ethanol. The dispersed Pd nanoparticles of much large size () were grown from the by keeping the colloid of undisturbed for 150 days at room temperature around 20 °C. The aggregates of () were prepared through an agglomeration process induced during a potential cyclic scanning between −0.25 V and 1.25 V for 20 min at a scan rate of 50 mV s⁻¹. Scanning electron microscope (SEM) patterns confirmed such aggregation of . Fourier transform infrared (FTIR) spectroscopy together with CO adsorption as probe reaction was employed in studies of IR optical properties of the prepared Pd nanoparticles. The results demonstrated that CO adsorbed on films substrated on CaF₂ IR window or glassy carbon (GC) electrode yielded two strong IR absorption bands around 1970 cm⁻¹ and 1910 cm⁻¹, which were assigned to IR absorption of CO bonded on asymmetric and symmetric bridge sites, respectively. Similar IR bands were observed in spectra of CO adsorbed on films, except the IR bands were much weak, whereas CO adsorbed on film produced an IR absorption band near 1906 cm⁻¹, and an anomalous IR absorption band whose direction has been completely inverted around 1956 cm⁻¹. The direction inversion of the IR band of CO bonded to asymmetric bridge sites on was ascribed to the interaction between Pd nanoparticles inside the aggregates. Based on FTIR spectroscopic and cyclic voltammetric results, the aggregation mechanism of Pd nanoparticles from to has been suggested that the agglomeration of Pd nanoparticles was driven by the alteration of electric field across electrode-electrolyte interface, when the PVP stabilizer was stripped via oxidation during cyclic voltammetry.     

磁响应交联糖化酶聚集体的制备及催化特性

提出了一种采用羧基磁性纳米粒子制备杂化磁响应交联酶聚集体（M-CLEAs）的方法。表面羧基修饰的约10 nm的磁性纳米粒子与酶分子表面的氨基位点通过静电相互作用,形成复合物,在磁场作用下可将磁性纳米粒子-酶复合物从溶液中分离,经戊二醛交联即形成M-CLEAs。传统的表面氨基修饰的磁性纳米粒子与酶需在沉淀剂作用下,从溶液中分离,而后采用戊二醛共交联,而本方法无须沉淀剂,过程更为简化。以糖化酶为对象,对该过程的影响因素（交联时间、pH、酶浓度、戊二醛浓度等条件）进行了探索,并对制得的M-CLEAs的酶学性质进行了较为详细考察。结果表明,最优制备条件为：酶浓度1 mg·ml^-1,磁流体浓度10 mg·ml^-1,戊二醛浓度0.25%（质量体积比）,在pH 6.0下交联反应6 h,最终载酶量可达80 mg·g^-1、比活为50 U·mg^-1。制得的固定化酶pH稳定性、热稳定性和储存稳定性均显著改善,可实现糖化酶重复使用10次,仍保留接近60%的酶活。     

Fabrication of ferrogels using different magnetic nanoparticles and their performance on protein adsorption

Magnetic biomaterials were prepared using magnetite and chitosan‐coated magnetite nanoparticles (CSNPs) dispersed in poly(vinyl alcohol) gels. Two different methods were developed to obtain ferrogels: in situ co‐precipitation of magnetite (Ferro‐IS) and by adding previously synthesized CSNPs to the neat matrix (Ferro‐CSNPs). In both cases, the crosslinking was carried out by freezing ? thawing (F‐T). The as‐prepared materials as well as precursor CSNPs were characterized by Fourier transform infrared spectroscopy, electronic microscopy (scanning and transmission), X‐ray diffraction, ζ potential, dynamic light scattering, thermogravimetric analysis, differential scanning calorimetry and magnetic properties. The performance of these gels as protein adsorbents was evaluated. Batch adsorption experiments were carried out using bovine serum albumin (BSA) as a model. Substantially different adsorption behaviour was found using Ferro‐IS and Ferro‐CSNPs. This was assigned to dissimilar bonding mechanisms of BSA to the ferrogel matrix. Hence, biomaterials potentially useful in drug delivery as well as in protein purification fields may be prepared by a relatively simple, non‐toxic and low cost method. © 2013 Society of Chemical Industry     

Influence of magnetic casting on the permeability and anti-fouling properties of a novel iron oxide/alumina/polysulfone mixed matrix membrane

Novel mixed matrix membranes (MMMs) were fabricated using Fe₃O₄, and Al₂O₃ nanoparticles (NPs) were added to the polysulfone (PSf) and N-methylpyrrolidone (NMP) solution. The nanocomposite membranes were fabricated using the NIPS (non-solvent induced phase separation) method. In order to create preferential permeation pathways for water across the MMMs, membrane formation is accomplished with an external magnetic field. Using magnetic casting cause the targeted placement of NPs in the best location and orientation. The performance of the prepared membranes was examined in terms of pure water flux and fouling parameters. Magnetic casting considerably increased pure water flux and decreased the total resistance of the optimum mixed matrix membrane, which contains 0.2% wt. of Fe₃O₄ NPs to 1175 L/m²h and 13.4 * 10¹¹ (m⁻¹), respectively. This is explained by the ordering of magnetic nanoparticles on the membrane sub-layer cast under the magnetic field of 500 mT, which changed the sub-layer structure. Less rough membrane surface of the mixed matrix membranes offered preferable anti-fouling properties against fouling by BSA proteins. The characterization of fabricated membranes was carried out using field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), energy dispersive X-ray (EDX), and water contact angle measurement methods.     

Synthesis and adsorptive properties of sulfonated nanocomposites based on carbon-encapsulated iron nanoparticles and styrene-p-divinylbenzene copolymer

ABSTRACT

A method of the synthesis of novel magnetic nanocomposite adsorbent of Fe(III) from aqueous solutions is presented. The nanocomposites consisted of carbon-encapsulated iron nanoparticles and styrene-p-divinylbenzene copolymer. The adsorptive active sites were introduced via the post-synthesis sulfonation. The presented sulfonated magnetic nanocomposite adsorbents can be easily separated using permanent magnets and their adsorption performance was comparable to the commercially available ion-exchange resins. The determined maximum adsorption capacities were between 10.9 and 49.5 mg?g^?1, whilst the equilibrium was reached for the contact time lower than 60 minutes.     

Electrochemical preparation of iron cuboid nanoparticles and their catalytic properties for nitrite reduction

Iron cuboid nanoparticles supported on glassy carbon (denoted nm-Fe/GC) were prepared by electrochemical deposition under cyclic voltammetric (CV) conditions. The structure and composition of the Fe nanomaterials were characterized by scanning electron microscopy (SEM), selected area electron diffraction (SAED), X-ray diffraction (XRD) and energy dispersive X-ray analysis (EDX). The results demonstrated that the Fe cuboid nanoparticles are dispersed discretely on GC substrate with an average size ca. 171 nm, and confirmed that the electrochemical synthesized nanocubes are single crystals of pure Fe. The catalytic properties of the Fe cuboid nanoparticles towards nitrite electroreduction were investigated, and enhanced electrocatalytic activity of the Fe nanocubes has been determined. In comparison with the data obtained on a bulk-Fe electrode, the onset potential of nitrite reduction on nm-Fe/GC is positively sifted by 100 mV, and the steady reduction current density is enhanced about 2.4-3.2 times.     

Aqueous chemical synthesis of iron oxides magnetic nanoparticles of different morphology and mesostructure

Magnetic nanoparticles of magnetite structure were obtained by the aqueous chemical synthesis, namely: using the chemical co-precipitation from the 1:2 M ratio mix of the iron chlorides (II, III) water solution with the ammonia used as precipitation agent as well as with oleic acid. Obtained nanopowders were studied using the X-Ray diffraction, infrared spectroscopy, scanning and transmission electron microscopy, low-temperature nitrogen absorption, and small-angle X-Ray scattering methods in order to determine the influence of synthesis techniques (homogenization procedure, separation methods – decantation, vacuum filtration, rotary evaporation, or magnetic separation), on the phase composition, size, morphology and magnetic parameters of the nanoparticles. It was demonstrated that the value of the specific surface area of nanoparticles with the average size of 10–20 nm is relatively high (75–132 m²/g) and their shape is lamellar or rod-shaped as well as cylindrical (round). The technique of separating nanoparticles from the mother liquor had a dominant effect on the morphology of nanoparticles. Dynamic and Electrophoretic Light Scattering methods showed that homogenization procedure, separation methods and especially surface modification with oleic acid affect the size and surface charge of the nanopowders.     

精氨酸修饰的磁性纳米基因载体的研究

采用多层修饰方法制备出精氨酸修饰的磁性纳米基因载体,对样品进行了粒度分析、Zeta电位分析、耐酸性能、生物相容性、体外细胞转染性能研究。结果显示,精氨酸修饰的磁性纳米颗粒均匀,分散性好,大多呈圆球型,平均粒径为15 nm,粒径范围10~20 nm,其Zeta电位为+29.3 mV;多层修饰的纳米磁粒在pH 2.0的酸中具有很好的耐酸性能,而未处理的纳米粒子在酸溶液中发生了溶解。MTT实验结果显示,纳米颗粒与细胞有良好的生物相容性;体外细胞转染的结果表明,精氨酸修饰的纳米磁粒能介导pEGFP-N1质粒转染HepG2细胞,并在细胞中表达绿色荧光蛋白。因此,精氨酸修饰的磁性纳米颗粒作为一种新型非病毒基因载体具有介导核酸类生物大分子的应用价值。     

Application of magnetic nanoparticles to gene delivery

Nanoparticle technology is being incorporated into many areas of molecular science and biomedicine. Because nanoparticles are small enough to enter almost all areas of the body, including the circulatory system and cells, they have been and continue to be exploited for basic biomedical research as well as clinical diagnostic and therapeutic applications. For example, nanoparticles hold great promise for enabling gene therapy to reach its full potential by facilitating targeted delivery of DNA into tissues and cells. Substantial progress has been made in binding DNA to nanoparticles and controlling the behavior of these complexes. In this article, we review research on binding DNAs to nanoparticles as well as our latest study on non-viral gene delivery using polyethylenimine-coated magnetic nanoparticles.     

复印墨粉用四氧化三铁的制备

主要研究了在碱性条件下，由经过处理的工业级硫酸亚铁和氢氧化钠通过氧化沉淀的方法，制备适合复印墨粉用高档四氧化三铁磁粉。介绍了硫酸亚铁和氢氧化钠的反应原理、工艺流程以及不同的m（Fe）／m（NaOH）、加料方式、反应体系的pH、鼓气量、鼓气时间、以及分散剂对产品性能的影响。制备的四氧化三铁磁粉纯度高，颗粒大小均匀，磁性能好，价格低廉，能够满足国内复印机市场需求。     

Synthesis of Ni nanoparticles with controllable magnetic properties by atmospheric pressure microplasma assisted process

An atmospheric pressure microplasma technique is demonstrated for the gas phase synthesis of Ni nanoparticles by plasma‐assisted nickelocene dissociation at different conditions. The dissociation process and the products are characterized by complementary analytical methods to establish the relationship between operational conditions and product properties. The innovation is to show proof‐of‐principle of a new synthesis route which offers access to less costly and less poisonous reactant, a higher quality product, and a simple, continuous and pre/post treatment‐free manner with chance for fine‐tuning “in‐flight.” Results show that Ni nanoparticles with controllable magnetic properties are obtained, in which flexible adjustment of product properties can be achieved by tuning operational parameters. At the optimized condition only fcc Ni nanoparticles are formed, with saturation magnetization value of 44.4 mAm²/g. The upper limit of production rate for Ni nanoparticles is calculated as 4.65 × 10^?3 g/h using a single plasma jet, but the process can be scaled‐up through a microplasma array design. In addition, possible mechanisms for plasma‐assisted nickelocene dissociation process are discussed. © 2017 The Authors AIChE Journal published by Wiley Periodicals, Inc. on behalf of American Institute of Chemical Engineers AIChE J, 64: 1540–1549, 2018     

Effects of annealing on the structural and magnetic properties of flame spray pyrolyzed MnFe2O4 nanoparticles

In this study, manganese ferrite (MnFe₂O₄) nanoparticles were produced through flame spray pyrolysis (FSP). To investigate the effects of heat treatment, the nanoparticles were annealed between 400 and 650°C for 4 h in air in a comparative manner. The structural, chemical, morphological, and magnetic properties of the nanoparticles were evaluated using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), dynamic light scattering (DLS), and vibrating sample magnetometry (VSM), respectively. The XRD results showed that the nanoparticles synthesized by the FSP method exhibited the MnFe₂O₄ spinel ferrite structure. The annealing process led to the decomposition of MnFe₂O₄ into various phases. According to the morphological analysis, the as-synthesized particles were hemispherical–cubic in shape and had an average particle size of less than 100 nm. In addition, the chemical bond structures of the nanoparticles were confirmed in detail by XPS elemental analysis. The highest saturation magnetization was recorded as 33.50 emu/g for the as-produced nanoparticles. The saturation magnetization of the nanoparticles decreased with increasing annealing temperature, while coercivity increased.     

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.