Magnetic Silica Nanoparticles Research Articles

ChemInform Abstract: Separation of Enantiomers with Magnetic Silica Nanoparticles Modified by a Chiral Selector: Enantioselective Fishing.

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Facile Fabrication of Ultrafine Hollow Silica and Magnetic Hollow Silica Nanoparticles by a Dual-Templating Approach.

The development of synthetic process for hollow silica materials is an issue of considerable topical interest. While a number of chemical routes are available and are extensively used, the diameter of hollow silica often large than 50 nm. Here, we report on a facial route to synthesis ultrafine hollow silica nanoparticles (the diameter of ca. 24 nm) with high surface area by using cetyltrimethylammmonium bromide (CTAB) and sodium bis(2-ethylhexyl) sulfosuccinate (AOT) as co-templates and subsequent annealing treatment. When the hollow magnetite nanoparticles were introduced into the reaction, the ultrafine magnetic hollow silica nanoparticles with the diameter of ca. 32 nm were obtained correspondingly. Transmission electron microscopy studies confirm that the nanoparticles are composed of amorphous silica and that the majority of them are hollow.

Studies on Preparation of Photosensitizer Loaded Magnetic Silica Nanoparticles and Their Anti-Tumor Effects for Targeting Photodynamic Therapy.

As a fast developing alternative of traditional therapeutics, photodynamic therapy (PDT) is an effective, noninvasive, nontoxic therapeutics for cancer, senile macular degeneration, and so on. But the efficacy of PDT was compromised by insufficient selectivity and low solubility. In this study, novel multifunctional silica-based magnetic nanoparticles (SMNPs) were strategically designed and prepared as targeting drug delivery system to achieve higher specificity and better solubility. 2,7,12,18-Tetramethyl-3,8-di-(1-propoxyethyl)-13,17-bis-(3-hydroxypropyl) porphyrin, shorted as PHPP, was used as photosensitizer, which was first synthesized by our lab with good PDT effects. Magnetite nanoparticles (Fe3O4) and PHPP were incorporated into silica nanoparticles by microemulsion and sol–gel methods. The prepared nanoparticles were characterized by transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy and fluorescence spectroscopy. The nanoparticles were approximately spherical with 20–30 nm diameter. Intense fluorescence of PHPP was monitored in the cytoplasm of SW480 cells. The nanoparticles possessed good biocompatibility and could generate singlet oxygen to cause remarkable photodynamic anti-tumor effects. These suggested that PHPP-SMNPs had great potential as effective drug delivery system in targeting photodynamic therapy, diagnostic magnetic resonance imaging and magnetic hyperthermia therapy.

A Selective Fluoroionophore Based on BODIPY‐functionalized Magnetic Silica Nanoparticles: Removal of Pb2+ from Human Blood

Get the lead out: The title fluorescence receptor exhibits a high affinity and selectivity for Pb(2+) over competing metal ions in water (see picture) with an overall emission change of approximately 8-fold at the emission maximum for Pb(2+). The fluorescence receptor can remove 96 % of 100 ppb Pb(2+) from human blood, and can be useful and effective for the selective and rapid removal of Pb(2+) in vivo.

A Selective Fluoroionophore Based on BODIPY‐functionalized Magnetic Silica Nanoparticles: Removal of Pb2+ from Human Blood

AbstractWeg mit Blei: Der Fluoreszenzrezeptor im Titel zeichnet sich durch eine hohe Affinität und Selektivität für Pb2+ gegenüber konkurrierenden Metallionen in Wasser aus (siehe Bild), wobei der Faktor der gesamten Emissionsänderung am Emissionsmaximum für Pb2+ etwa 8 beträgt. Der Fluoreszenzrezeptor kann 96 % von 100 ppb Pb2+ aus menschlichem Blut entfernen und eignet sich für die effektive, selektive und schnelle Entfernung von Pb2+ in vivo.magnified image

Effect of surface functionality of magnetic silica nanoparticles on the cellular uptake by glioma cells in vitro

The cellular uptake efficiency of nanoparticles depends mainly on the surface characteristics of these materials. In this study, amine- and ester-terminated polyamidoamine (PAMAM) dendrimers were used to functionalize fluorescein-doped magnetic mesoporous silica nanoparticles (FMNPs) to evaluate the effect of surface functionality on cellular uptake by glioma cells. The successful synthesis of these materials was confirmed by transmission electron microscopy (TEM), thermogravimetric analysis (TGA) and zeta potential titration. Neither of these materials showed acute cytotoxicity and it was demonstrated that the different surface functionalities regulated the ability of the nanoparticles to cross cell membranes. In addition to serving as an imaging agent, fluorescein isothiocyanate isomer I (FITC) was used as a model drug to evaluate the drug release rates of these drug delivery systems.

Separation of enantiomers with magnetic silica nanoparticles modified by a chiral selector: enantioselective fishing

Magnetic silica nanoparticles modified by a chiral selector were demonstrated to be useful in magnetic field induced separation of enantiomers.

One-pot construction of doxorubicin conjugated magnetic silica nanoparticles

Doxorubicin (DOX) conjugated magnetic silica nanoparticles (DOX–Fe3O4–SiO2) are successfully fabricated using a new one-pot method without need for the process of inconvenient multistep synthesis in advance, based on the condensation of DOX and the silica precursor 3-isocyanatopropyltriethoxysilane (ICPTES), followed by the spontaneous formation of a silica coating onto the surface of Fe3O4nanoparticlesvia sol–gel polymerization of triethoxysilane. Mass spectroscopy provides evidence that doxorubicin is conjugated to ICPTES via a urea bond (–NHCONH–) via the reaction of the amino groups of DOX with the isocyanate group (–NCO) of ICPTES in water. The obtained magnetic nanoparticles are well dispersed. Their mean diameter is about 66.9 nm with a narrow size distribution. The conjugated DOX–SiO2–Fe3O4nanoparticles exhibited a higher loading efficiency of 60.5 ± 3.7% and a more sustained release profile than SiO2nanoparticles containing physically-entrapped DOX. It is anticipated that fine-tuning of other drugs or bioactive molecules containing –NH2groups to Fe3O4/SiO2nanoparticles would foster innovative avenues for the development of smart drug delivery and controlled release systems.

Magnetic nanoparticles supported ionic liquids for lipase immobilization: Enzyme activity in catalyzing esterification

Candida rugosa lipase was immobilized on magnetic nanoparticles supported ionic liquids having different cation chain length (C 1, C 4 and C 8) and anions (Cl −, BF 4 − and PF 6 −). Magnetic nanoparticles supported ionic liquids were obtained by covalent bonding of ionic liquids–silane on magnetic silica nanoparticles. The particles are superparamagnetic with diameter of about 55 nm. Large amount of lipase (63.89 mg/(100 mg carrier)) was loaded on the support through ionic adsorption. Activity of the immobilized lipase was examined by the catalysis of esterification between oleic acid and butanol. The activity of bound lipase was 118.3% compared to that of the native lipase. Immobilized lipase maintained 60% of its initial activity even when the temperature was up to 80 °C. In addition, immobilized lipase retained 60% of its initial activity after 8 repeated batches reaction, while no activity was detected after 6 cycles for the free enzyme.

Polyethylene glycol grafting and attachment of encapsulated magnetic iron oxide silica nanoparticles onto chlorosilanized single-wall carbon nanotubes

It is demonstrated that functionalization of single-wall carbon nanotubes (SWCNTs) can be carried out using simple chlorosilane chemistry, which allows coupling of the SWCNTs with external chemical species. As a result, organic polymers and magnetically iron oxide-in-silica nanoparticles are specifically bonded onto SWCNTs. It is also found that the SWCNTs functionalized with long PEG chains greatly enhance dispersion of the carbon structure in water. Furthermore, the SWCNT–COO–Si(Fe 3O 4@SiO 2) can be quickly separated and redispersed from their aqueous colloid with the application of external magnetic field.

Development of C 18-functionalized magnetic silica nanoparticles as sample preparation technique for the determination of ergosterol in cigarettes by microwave-assisted derivatization and gas chromatography/mass spectrometry

Ergosterol is one of the important precursors of tumorigenic polynuclear aromatic hydrocarbons. A large amount of ergosterol is present in mildewy cigarettes, which derives from fungal contaminations. In this paper, a novel approach based on C 18-functionalized magnetic silica nanoparticles (C 18-f-MS NPs) coupled with microwave-assisted derivatization and gas chromatography/mass spectrometry (GC/MS) was developed for the rapid enrichment and determination of ergosterol in cigarettes. Due to that, microwave-assisted derivatization requires very short time (several minutes), and the extraction and concentration of ergosterol become the key step in the sample preparation process. In this study, the prepared C 18-f-MS NPs with its unique properties (high surface area and strong magnetism) provided an efficient way for extraction and concentration of ergosterol in the samples. Additionally, the analyte of ergosterol adsorbed with C 18-f-MS NPs in cigarettes can be simply and rapidly isolated (only about 2 s) through placing a strong magnet on the bottom of container. In this work, different parameters such as added amounts of C 18-f-MS NPs, extraction temperature, and extraction time were optimized to enhance the extraction efficiency. Method validations (linear range, detection limit, precision, and recovery) were also studied. The results obtained by the optimal conditions showed that the proposed method based on C 18-f-MS NPs was a simple, high efficient, and had a rapid approach for the enrichment of ergosterol in cigarettes and was successfully applied to the analysis of ergosterol in normal and mildewy cigarettes followed by microwave-assisted derivatization and GC/MS.

A novel mimetic peroxidase catalyst by using magnetite-containing silica nanoparticles as carriers

A method for coating magnetite and mimetic enzyme (hemin) with amorphous silica to form a novel mimetic peroxidase (magnetite-hemin/SiO2) has been developed by combining reverse microemulsion and the modified Stober method. The magnetic silica nanoparticle supported hemin has a long-term stability toward temper- ature and good reusability. They can be easily separated from the reaction solution by using an external magnetic field and reused directly for next round of reaction. The peroxidase activity of the magnetite-hemin/SiO2 was studied based on its catalytic effect on the reaction of p- hydroxyphenylacetic acid and H2O2. The results indicated that the catalytic activity of the new mimetic enzyme catalyst is higher than that of the free hemin. The possibility of its application was proven by the determination of H2O2, with the detection limits of 7.3 nmol L �1 H2O2.

Magnetic sensitivity enhanced novel fluorescent magnetic silica nanoparticles for biomedicalapplications

We synthesized novel fluorescent magnetic silica nanoparticles (FMSNPs) containing largemagnetic components for biomedical application. By employing assemblies of magneticnanoparticles as kernels against FMSNPs, both the saturation of magnetization and themagnetic resonance (MR) signal intensity were significantly enhanced. Furthermore, thecellular binding of FMSNPs was improved by introducing a positive charge on the surfaceof the FMSNPs, and fluorescent dyes on the surface of FMSNPs enable optical imaging ofsub-cellular regions.

Design of Superparamagnetic Iron Oxide Nanoparticle for Purification of Recombinant Proteins

This article reports the synthesis, characterization and also the use of surface modified iron oxide nanoparticles in affinity separation of his-tagged protein. Magnetite particles were prepared by simple coprecipitation of Fe3+/Fe2+ in aqueous medium and then subsequently coated with silica following a sol-gel route. Iminodiacetate was immobilized on them through a silane-coupling agent and charged with Ni2+. These Ni2+ charged magnetic silica nanoparticles have been shown as an efficient carrier, binder and anchor to obtain his-tagged protein directly from total cell lysate. The structural characteristics of the powders were studied by XRD. Magnetic silica particles with 12 nm and aggregate size 90 nm containing inverse spinel magnetite core were observed by transmission electron micrograph and dynamic light scattering. The presence of surface-iminodiacetate groups was shown by FTIR and X-ray photoelectron spectra. The immobilization of Ni2+ through the surface chelating iminodiacetate groups was also studied by XPS. VSM measurement shows these iminodiacetate functionalized magnetic carriers have saturation magnetization 56 e.m.u./g at room temperature. Due to its high efficiency, cost-effectiveness, biocompatibility, and versatility, this magnetic nano-adsorbent may be used as a novel purification system for 6xHis-Tagged recombinant proteins.

Biofunctional magnetic nanoparticles as a general agent to immobilize proteins contained in traditional Chinese medicines

Maghemite nanoparticles were synthesized by the coprecipitation method. Silica was coated to the maghemite nanoparticles and amino silane was modified to the surface of the silica magnetic nanoparticles. We use the biofunctional magnetic nanoparticles as a general agent to immobilize and separate the proteins in a broad range from different traditional Chinese medicines. The transmission electron microscopy results showed that the average diameter of the well-dispersed silica-coated nanoparticles was about 60 nm. The Fourier transform infrared spectrum indicated that the amino group had been successfully coupled to the surface of the maghemite particles. And the protein immobilization effect was characterized by the microplate reader. The characterization results proved that the synthesized functional magnetic nanoparticles could effectively immobilize and separate the proteins from traditional Chinese medicines.

One-step synthesis of magnetic hollow silica and their application for nanomedicine

Magnetic nanoparticles are usually present in the form of magnetic carriers and used in nanomedicine and biosystem. In this paper, magnetic hollow silica (MHS) nanoparticles were fabricated by a one-step synthesis of Fe3O4 nanoparticles and then coating of silica on nanosized spherical calcium carbonate under alkaline conditions, in which nanosized calcium carbonate (CaCO3, 25–60nm) was used as a scarified template, tetraethoxysilane as a precursor, and Fe3O4 nanoparticles (∼5nm), formed in the initial reaction stage, as magnetic agents. The as-synthesized nanoparticles were immersed in a weak acetic acidic solution to remove CaCO3, forming MHS carriers. The nanostructures of the MHS carriers were characterized by scanning electron microscope, transmission electron microscope, and x-ray diffraction. Superconducting quantum interference device measurement exhibited that the MHS nanoparticles were superparamagnetic. Toxicity was tested for MHS carriers using rat brain microvascular endothelial cells. The cells treated with concentration lower than 50μg∕ml of the MHS nanoparticles showed no significant toxicity. After modification by silane coupling agent, the MHS carriers have strong absorption for ibuprofen in nanomedicine field.

Superparamagnetic silica nanoparticles with immobilized metal affinity ligands for protein adsorption

Superparamagnetic silica-coated magnetite (Fe 3O 4) nanoparticles with immobilized metal affinity ligands were prepared for protein adsorption. First, magnetite nanoparticles were synthesized by co-precipitating Fe 2+ and Fe 3+ in an ammonia solution. Then silica was coated on the Fe 3O 4 nanoparticles using a sol–gel method to obtain magnetic silica nanoparticles. The condensation product of 3-Glycidoxypropyltrimethoxysilane (GLYMO) and iminodiacetic acid (IDA) was immobilized on them and after charged with Cu 2+, the magnetic silica nanoparticles with immobilized Cu 2+ were applied for the adsorption of bovine serum albumin (BSA). Scanning electron micrograph showed that the magnetic silica nanoparticles with an average size of 190 nm were well dispersed without aggregation. X-ray diffraction showed the spinel structure for the magnetite particles coated with silica. Magnetic measurement revealed the magnetic silica nanoparticles were superparamagnetic and the saturation magnetization was about 15.0 emu/g. Protein adsorption results showed that the nanoparticles had high adsorption capacity for BSA (73 mg/g) and low nonspecific adsorption. The regeneration of these nanoparticles was also studied.

Preparation, characterization and application of magnetic silica nanoparticle functionalized multi-walled carbon nanotubes

Magnetic silica nanoparticle functionalized multi-walled carbon nanotubes (MS-MWNTs) were prepared, characterized and used for the convenient, rapid and efficient separation of trace aromatic compounds.

Applications of magnetic targeting in diagnosis and therapy--possibilities and limitations: a mini-review.

Applications of magnetic targeting in diagnosis and therapy--possibilities and limitations: a mini-review.