by Keyword: Iron oxide

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Villa, Katherine, Parmar, Jemish, Vilela, Diana, Sánchez, Samuel, (2018). Metal-oxide-based microjets for the simultaneous removal of organic pollutants and heavy metals ACS Applied Materials & Interfaces , 10, (24), 20478-20486

Water contamination from industrial and anthropogenic activities is nowadays a major issue in many countries worldwide. To address this problem, efficient water treatment technologies are required. Recent efforts have focused on the development of self-propelled micromotors that provide enhanced micromixing and mass transfer by the transportation of reactive species, resulting in higher decontamination rates. However, a real application of these micromotors is still limited due to the high cost associated to their fabrication process. Here, we present Fe2O3-decorated SiO2/MnO2 microjets for the simultaneous removal of industrial organic pollutants and heavy metals present in wastewater. These microjets were synthesized by low-cost and scalable methods. They exhibit an average speed of 485 ± 32 μm s–1 (∼28 body length per s) at 7% H2O2, which is the highest reported for MnO2-based tubular micromotors. Furthermore, the photocatalytic and adsorbent properties of the microjets enable the efficient degradation of organic pollutants, such as tetracycline and rhodamine B under visible light irradiation, as well as the removal of heavy metal ions, such as Cd2+ and Pb2+.

Keywords: Micromotors, Photocatalytic, Water purification, Fenton, Magnetic control, Iron oxide, Manganese oxide

Tahirbegi, I.B., Pardo, W.A., Alvira, M., Mir, M., Samitier, J., (2016). Amyloid Aβ 42, a promoter of magnetite nanoparticle formation in Alzheimer's disease Nanotechnology , 27, (46), 465102

The accumulation of iron oxides - mainly magnetite - with amyloid peptide is a key process in the development of Alzheimer's disease (AD). However, the mechanism for biogeneration of magnetite inside the brain of someone with AD is still unclear. The iron-storing protein ferritin has been identified as the main magnetite-storing molecule. However, accumulations of magnetite in AD are not correlated with an increase in ferritin, leaving this question unresolved. Here we demonstrate the key role of amyloid peptide Aβ 42, one of the main hallmarks of AD, in the generation of magnetite nanoparticles in the absence of ferritin. The capacity of amyloid peptide to bind and concentrate iron hydroxides, the basis for the formation of magnetite, benefits the spontaneous synthesis of these nanoparticles, even under unfavorable conditions for their formation. Using scanning and transmission electron microscopy, electron energy loss spectroscopy and magnetic force microscopy we characterized the capacity of amyloid peptide Aβ 42 to promote magnetite formation.

Keywords: Alzheimer disease (AD), amyloid peptide Ab42, magnetite nanoparticle, metallobiomolecule, iron oxide, neurodegenerative brain diseases

Fernández-Remolar, D. C., Santamaría, J., Amils, R., Parro, V., Gómez-Ortíz, D., Izawa, M. R. M., Banerjee, N. R., Pérez-Rodríguez', R., Rodríguez, N., López-Martínez, N., (2015). Formation of iron-rich shelled structures by microbial communities Journal of Geophysical Research: Biogeosciences , 120, (1), 147-168

In this paper, we describe the discovery and characterization of shelled structures that occur inside galleries of Pyrenees mines. The structures are formed by the mineralization of iron and zinc oxides, dominantly franklinite (ZnFe2O4) and poorly ordered goethite (α-FeO(OH)). Subsurface oxidation and hydration of polymetallic sulfide orebodies produce solutions rich in dissolved metal cations including Fe2+/3+ and Zn2+. The microbially precipitated shell-like structure grows by lateral or vertical stacking of thin laminae of iron oxide particles which are accreted mostly by fungal filaments. The resulting structures are composed of randomly oriented aggregates of needle-like, uniform-sized crystals, suggesting some biological control in the structure formation. Such structures are formed by the integration of two separated shells, following a complex process driven likely by different strategies of fungal microorganisms that produced the complex macrostructure.

Keywords: Geobiology, Iron oxides, Microbial mineralization

Seo, K. D., Kwak, B. K., Sánchez, S., Kim, D. S., (2015). Microfluidic-assisted fabrication of flexible and location traceable organo-motor IEEE Transactions on Nanobioscience , 14, (3), 298-304

In this paper, we fabricate a flexible and location traceable micromotor, called organo-motor, assisted by microfluidic devices and with high throughput. The organo-motors are composed of organic hydrogel material, poly (ethylene glycol) diacrylate (PEGDA), which can provide the flexibility of their structure. For spatial and temporal traceability of the organo-motors under magnetic resonance imaging (MRI), superparamagnetic iron oxide nanoparticles (SPION; Fe3O4) were incorporated into the PEGDA microhydrogels. Furthermore, a thin layer of platinum (Pt) was deposited onto one side of the SPION-PEGDA microhydrogels providing geometrical asymmetry and catalytic propulsion in aqueous fluids containing hydrogen peroxide solution, H2O2. Furthermore, the motion of the organo-motor was controlled by a small external magnet enabled by the presence of SPION in the motor architecture.

Keywords: Flexible, Hydrogel, Magnetic resonance imaging, Microfluidics, Micromotor, Microparticle, Organo-motor, Poly (ethylene glycol) diacrylate, Self-propulsion, Superparamagnetic iron oxide nanoparticles