Magnetically Recoverable Catalysts: Beyond Magnetic Separation

Here, we discuss several important aspects of magnetically recoverable catalysts which can be realized when magnetic oxide nanoparticles are exposed to catalytic species and catalytic reaction media. In such conditions magnetic oxides can enhance performance of catalytic nanoparticles due to (i) electronic effects, (ii) catalyzing reactions which are beneficial for the final reaction outcome, or (iii) providing a capacity to dilute catalytic metal oxide species, leading to an increase of oxygen vacancies. However, this approach should be used when the magnetic oxides are stable in reaction conditions and do not promote side reactions. Incorporation of another active component, i.e., a graphene derivative, in the magnetically recoverable catalyst constitutes a smart design of a catalytic system due to synergy of its components, further enhancing catalytic properties

Magnetic Drug Delivery: Where the Field Is Going

Targeted delivery of anticancer drugs is considered to be one of the pillars of cancer treatment as it could allow for a better treatment efficiency and less adverse effects. A promising drug delivery approach is magnetic drug targeting which can be realized if a drug delivery vehicle possesses a strong magnetic moment. Here, we discuss different types of magnetic nanomaterials which can be used as magnetic drug delivery vehicles, approaches to magnetic targeted delivery as well as promising strategies for the enhancement of the imaging-guided delivery and the therapeutic action

BikeNet: Preventing theft, building community

This report discusses the Save the Bike Project and the BikeNet App, and the ways it helps prevent and recover stolen bikes.Ope

Zn2+ ion surface enrichment in doped iron oxide nanoparticles leads to charge carrier density enhancement

Here, we report the development of monodisperse Zn-doped iron oxide nanoparticles (NPs) with different amounts of Zn (ZnxFe3-xO4, 0 < x < 0.43) by thermal decomposition of a mixture of zinc and iron oleates. The as-synthesized NPs show a considerable fraction of wüstite (FeO) which is transformed to spinel upon 2 h oxidation of the NP reaction solutions. At any Zn doping amounts, we observed the enrichment of the NP surface with Zn2+ ions, which is enhanced at higher Zn loadings. Such a distribution of Zn2+ ions is attributed to the different thermal decomposition profiles of Zn and Fe oleates, with Fe oleate decomposing at much lower temperature than that of Zn oleate. The decomposition of Zn oleate is, in turn, catalyzed by a forming iron oxide phase. The magnetic properties were found to be strongly dependent on the Zn doping amounts, showing the saturation magnetization to decrease by 9 and 20% for x = 0.05 and 0.1, respectively. On the other hand, X-ray photoelectron spectroscopy near the Fermi level demonstrates that the Zn0.05Fe2.95O4 sample displays a more metallic character (a higher charge carrier density) than undoped iron oxide NPs, supporting its use as a spintronic material

Metal oxide–zeolite composites in transformation of methanol to hydrocarbons : do iron oxide and nickel oxide matter?

The methanol-to-hydrocarbon (MTH) reaction has received considerable attention as utilizing renewable sources of both value-added chemicals and fuels becomes a number one priority for society. Here, for the first time we report the development of hierarchical zeolites (ZSM-5) containing both iron oxide and nickel oxide nanoparticles. By modifying the iron oxide (magnetite, Fe3O4) amounts, we are able to control the catalyst activity and the product distribution in the MTH process. At the medium Fe3O4 loading, the major fraction is composed of C9–C11 hydrocarbons (gasoline fraction). At the higher Fe3O4 loading, C1–C4 hydrocarbons prevail in the reaction mixture, while at the lowest magnetite loading the major component is the C5–C8 hydrocarbons. Addition of Ni species to Fe3O4–ZSM-5 leads to the formation of mixed Ni oxides (NiO/Ni2O3) positioned either on top of or next to Fe3O4 nanoparticles. This modification allowed us to significantly improve the catalyst stability due to diminishing coke formation and disordering of the coke formed. The incorporation of Ni oxide species also leads to a higher catalyst activity (up to 9.3 g(methanol)/(g(ZSM-5) × h)) and an improved selectivity (11.3% of the C5–C8 hydrocarbons and 23.6% of the C9–C11 hydrocarbons), making these zeolites highly promising for industrial applications

Magnetically Recoverable Catalysts: Beyond Magnetic Separation

Here, we discuss several important aspects of magnetically recoverable catalysts which can be realized when magnetic oxide nanoparticles are exposed to catalytic species and catalytic reaction media. In such conditions magnetic oxides can enhance performance of catalytic nanoparticles due to (i) electronic effects, (ii) catalyzing reactions which are beneficial for the final reaction outcome, or (iii) providing a capacity to dilute catalytic metal oxide species, leading to an increase of oxygen vacancies. However, this approach should be used when the magnetic oxides are stable in reaction conditions and do not promote side reactions. Incorporation of another active component, i.e., a graphene derivative, in the magnetically recoverable catalyst constitutes a smart design of a catalytic system due to synergy of its components, further enhancing catalytic properties

Design of biocatalysts for efficient catalytic processes

Biocatalysts based on immobilized enzymes received considerable attention due to important applications in syntheses of value-added chemicals, pharmaceuticals and drug intermediates with great catalytic efficiency and high yields of target molecules. The important advantages of such biocatalysts are enhanced stability in tolerant pH and temperature range, separation from reaction solutions, stability in repeated use, etc. In this review, we discuss recent findings in biocatalyst design, in particular, types of promising supports, the biocatalyst surface modification, and incorporation of magnetic nanoparticles for facilitated magnetic recovery. Furthermore, we highlight the development of multienzyme and enzyme/nanoparticle catalysts for cascade reactions, which are carried out in a one-pot process and allow elimination of isolation and purification of intermediates

Magnetic Nanoparticle-Containing Supports as Carriers of Immobilized Enzymes: Key Factors Influencing the Biocatalyst Performance

In this short review (Perspective), we identify key features of the performance of biocatalysts developed by the immobilization of enzymes on the supports containing magnetic nanoparticles (NPs), analyzing the scientific literature for the last five years. A clear advantage of magnetic supports is their easy separation due to the magnetic attraction between magnetic NPs and an external magnetic field, facilitating the biocatalyst reuse. This allows for savings of materials and energy in the biocatalytic process. Commonly, magnetic NPs are isolated from enzymes either by polymers, silica, or some other protective layer. However, in those cases when iron oxide NPs are in close proximity to the enzyme, the biocatalyst may display a fascinating behavior, allowing for synergy of the performance due to the enzyme-like properties shown in iron oxides. Another important parameter which is discussed in this review is the magnetic support porosity, especially in hierarchical porous supports. In the case of comparatively large pores, which can freely accommodate enzyme molecules without jeopardizing their conformation, the enzyme surface ordering may create an optimal crowding on the support, enhancing the biocatalytic performance. Other factors such as surface-modifying agents or special enzyme reactor designs can be also influential in the performance of magnetic NP based immobilized enzymes