Concept: Iron oxide
Magnetic iron oxide nanoparticles were prepared using a sonochemical method under atmospheric conditions at a Fe(2+) to Fe(3+) molar ratio of 1:2. The iron oxide nanoparticles were subsequently coated with chitosan and gallic acid to produce a core-shell structure.
Azlactones have been prepared via Erlenmeyer synthesis from aromatic aldehydes and hippuric acid using Fe(2)O(3) nanoparticles under ultrasonic irradiation. Short reaction times, easy and quick isolation of the products, and excellent yields are the main advantages of this procedure.
The cerebral blood volume (CBV) is a crucial physiological indicator of tissue viability and vascular reactivity. Thus, noninvasive CBV mapping has been of great interest. For this, ultrasmall superparamagnetic iron oxide (USPIO) nanoparticles, including monocrystalline iron oxide nanoparticles, can be used as long-half-life, intravascular susceptibility agents of CBV MRI measurements. Moreover, CBV-weighted functional MRI (fMRI) with USPIO nanoparticles provides enhanced sensitivity, reduced large vessel contribution and improved spatial specificity relative to conventional blood oxygenation level-dependent fMRI, and measures a single physiological parameter that is easily interpretable. We review the physiochemical and magnetic properties, and pharmacokinetics, of USPIO nanoparticles in brief. We then extensively discuss quantifications of baseline CBV, vessel size index and functional CBV change. We also provide reviews of dose-dependent sensitivity, vascular filter function, specificity, characteristics and impulse response function of CBV fMRI. Examples of CBV fMRI specificity at the laminar and columnar resolution are provided. Finally, we briefly review the application of CBV measurements to functional and pharmacological studies in animals. Overall, the use of USPIO nanoparticles can determine baseline CBV and its changes induced by functional activity and pharmacological interventions. Copyright © 2012 John Wiley & Sons, Ltd.
In the pursuit of optimized magnetic nanostructures for diagnostic and therapeutic applications, the role of nanoparticle architecture has been poorly investigated. In this study, we demonstrate that the internal collective organization of multi-core iron oxide nanoparticles can modulate their magnetic properties in such a way as to critically enhance their hyperthermic efficiency and their MRI T1 and T2 contrast effect. Multi-core nanoparticles comprised of maghemite cores were synthesized through a polyol approach and subsequent electrostatic colloidal sorting was used to fractionate the suspensions by size, and hence magnetic properties. We obtained stable suspensions of citrate-stabilized nanostructures ranging from single-core 10 nm nanoparticles, to multi-core magnetically-cooperative 30 nm nanoparticles. Three dimensional oriented attachment of primary cores results in enhanced magnetic susceptibility and decreased surface disorder compared to individual cores, while preserving the superparamagnetic behavior of the assembly and potentiating thermal losses. Exchange coupling in the assembly modifies the dynamics of the magnetic moment in such a way that both the longitudinal and transverse NMR relaxivities are also enhanced. Long term MRI detection of tumour cells and their efficient destruction by magnetic hyperthermia can be achieved thanks to a facile and non-toxic cell uptake of these iron oxide nanostructures. This study proves for the first time that cooperative magnetic behavior within highly crystalline iron oxide superparamagnetic multi-core assemblies can improve simultaneously therapeutic and diagnosis effectiveness over existing nanostructures, while preserving biocompatibility.
We report a highly versatile and one-pot microwave route to the mass production of three-dimensional graphene-carbon nanotube-iron oxide nanostructures for the efficient removal of arsenic from contaminated water. The unique three-dimensional nanostructure shows that carbon nanotubes are vertically standing on graphene sheets and iron oxide nanoparticles are decorated on both the graphene and the carbon nanotubes. The material with iron oxide nanoparticles shows excellent absorption for arsenic removal from contaminated water, due to its high surface-to-volume ratio and open pore network of the graphene-carbon nanotube-iron oxide three-dimensional nanostructures.
Gene therapy is a very promising technology for treatment of liver diseases. Minicircle DNA (MCDNA) is a versatile gene vector, which possesses excellent features in bio-safety and duration of transgene expression. However, its application has been hampered by the lack of an efficient gene delivery system. In this study, we developed a magnetic resonance imaging (MRI) visible nanoparticle to monitor MCDNA gene delivery and explore the potential of gene therapy in vivo. The nanoparticle was constructed via self-assembly of stearic acid modified low molecular polyethyleneimine (stPEI) and superparamagnetic iron oxide (SPIO) nanocrystals. The multiple SPIO nanocrystals with a controlled clustering structure in the nanoparticles were designed to achieve high MRI sensitivity. Furthermore, the MCDNA was combined with the nanoparticles via electronic interaction. Through intrabiliary infusion, the stPEI-SPIO/MCDNA nanoparticles were efficiently delivered to liver that was visualized by MRI in vivo and confirmed by histology. Moreover, the MCDNA nanoparticles exhibited non-cytotoxicity with no obvious inflammation in the transfection sites. These results indicate that stPEI-SPIO nanoparticle is able to serve as both an efficient DNA vector delivery system and a sensitive agent for MRI visualization.
Ochres and earths: Matrix and chromophores characterization of 19th and 20th century artist materials
- Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy
- Published almost 8 years ago
The present paper describes the main results obtained from the characterization of a wide range of natural and synthetic ochre samples used in Portugal from the 19th to the 20th century, including powder and oil painting samples. The powder ochre samples came from several commercial distributors and from the collection of Joaquim Rodrigo (1912-1997), a leading Portuguese artist, particularly active during the sixties and seventies. The micro-samples of oil painting tubes came from the Museu Nacional de Arte Contemporânea-Museu do Chiado (National Museum of Contemporary Art-Chiado Museum) in Lisbon and were used by Columbano Bordalo Pinheiro (1857-1929), one of the most prominent naturalist Portuguese painters. These tubes were produced by the main 19th century colourmen: Winsor & Newton, Morin et Janet, Maison Merlin, and Lefranc. The samples have been studied using μ-Fourier Transform Infrared Spectroscopy (μ-FTIR), Raman microscopy, μ-Energy Dispersive X-ray fluorescence (μ-EDXRF), and X-ray diffraction (XRD). The analyzed ochres were found to be a mixture of several components: iron oxides and hydroxides in matrixes with kaolinite, gypsum and chalk. The results obtained allowed to identify and characterize the ochres according to their matrix and chromophores. The main chromophores where identified by Raman microscopy as being hematite, goethite and magnetite. The infrared analysis of the ochre samples allowed to divide them into groups, according to the composition of the matrix. It was possible to separate ochres containing kaolinite matrix and/or sulfate matrix from ochres where only iron oxides and/or hydroxides were detected. μ-EDXRF and Raman were the best techniques to identify umber, since the presence of elements such as manganese is characteristic of these pigments. μ-EDXRF also revealed the presence of significant amounts of arsenic in all Sienna tube paints.
Frequency-dependent NMR relaxation studies have been carried out on water (polar) and cyclohexane (nonpolar) molecules confined inside porous ceramics containing variable amounts of iron oxide (III). The porous ceramics were prepared by compression of powders mixed with iron oxide followed by thermal treatment. The pore size distribution was estimated using a technique based on diffusion in internal fields that exposed a narrow distribution of macropore sizes with an average pore dimension independent of iron oxide content. The relaxation dispersion curves were obtained at room temperature using a fast field cycling NMR instrument. They display an increase of the relaxation rate proportional to the iron oxide concentration. This behavior is more prominent at low Larmor frequencies and is independent of the polar character of the confined molecules. The results reported here can be fitted well with a relaxation model considering exchange between molecules in the close vicinity of the paramagnetic centers located in the surface and bulk-like molecules inside the pores. This model allows the extraction of the transverse diffusional correlation time that can be related to the polar character of the confined molecules. Copyright © 2013 John Wiley & Sons, Ltd.
We tried to develop a multimodal iron oxide nanoparticles (IO NP) imaging probe by an encapsulation method using specific amphiphiles for (68)Ga-labeling and lymph node-targeting.
Liposome-capped core-shell mesoporous silica-coated superparamagnetic iron oxide nanoparticles called ‘magnetic protocells’ were prepared as novel nanocomposites and used for loading anticancer drug doxorubicin (DOX) for cellular toxicity study. Cytotoxicity of the magnetic protocells with or without DOX was tested in vitro on commercial MCF7 and U87 cell lines under alternating magnetic field. MCF7 cell line treated with the DOX-loaded nanoparticles under alternating magnetic field exhibited nearly 20% lower survival rate after 24 h compared with cells treated with free DOX and similarly, it was around 24% when applied to U87. The results indicate that the magnetic protocells could be useful for future cancer treatment in vivo by the combination of targeted drug delivery and magnetic hyperthermia.