Synthesis, Catalytic Properties and Application in Biosensorics of Nanozymes and Electronanocatalysts: A Review

The current review is devoted to nanozymes, i.e., nanostructured artificial enzymes which mimic the catalytic properties of natural enzymes. Use of the term “nanozyme” in the literature as indicating an enzyme is not always justified. For example, it is used inappropriately for nanomaterials bound with electrodes that possess catalytic activity only when applying an electric potential. If the enzyme-like activity of such a material is not proven in solution (without applying the potential), such a catalyst should be named an “electronanocatalyst”, not a nanozyme. This paper presents a review of the classification of the nanozymes, their advantages vs. natural enzymes, and potential practical applications. Special attention is paid to nanozyme synthesis methods (hydrothermal and solvothermal, chemical reduction, sol-gel method, co-precipitation, polymerization/polycondensation, electrochemical deposition). The catalytic performance of nanozymes is characterized, a critical point of view on catalytic parameters of nanozymes described in scientific papers is presented and typical mistakes are analyzed. The central part of the review relates to characterization of nanozymes which mimic natural enzymes with analytical importance (“nanoperoxidase”, “nanooxidases”, “nanolaccase”) and their use in the construction of electro-chemical (bio)sensors (“nanosensors”).

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Magnetite-Silica Core/Shell Nanostructures: From Surface Functionalization towards Biomedical Applications—A Review

Applied Sciences ◽

10.3390/app112211075 ◽

2021 ◽

Vol 11 (22) ◽

pp. 11075

Author(s):

Angela Spoială ◽

Cornelia-Ioana Ilie ◽

Luminița Narcisa Crăciun ◽

Denisa Ficai ◽

Anton Ficai ◽

...

Keyword(s):

Magnetite Nanoparticles ◽

Biomedical Applications ◽

Sol Gel ◽

Magnetic Nanomaterials ◽

Core Shell ◽

Synthesis Methods ◽

Shell Nanostructures ◽

Silica Core ◽

Magnetic Resonance Imaging Mri ◽

Co Precipitation

The interconnection of nanotechnology and medicine could lead to improved materials, offering a better quality of life and new opportunities for biomedical applications, moving from research to clinical applications. Magnetite nanoparticles are interesting magnetic nanomaterials because of the property-depending methods chosen for their synthesis. Magnetite nanoparticles can be coated with various materials, resulting in “core/shell” magnetic structures with tunable properties. To synthesize promising materials with promising implications for biomedical applications, the researchers functionalized magnetite nanoparticles with silica and, thanks to the presence of silanol groups, the functionality, biocompatibility, and hydrophilicity were improved. This review highlights the most important synthesis methods for silica-coated with magnetite nanoparticles. From the presented methods, the most used was the Stöber method; there are also other syntheses presented in the review, such as co-precipitation, sol-gel, thermal decomposition, and the hydrothermal method. The second part of the review presents the main applications of magnetite-silica core/shell nanostructures. Magnetite-silica core/shell nanostructures have promising biomedical applications in magnetic resonance imaging (MRI) as a contrast agent, hyperthermia, drug delivery systems, and selective cancer therapy but also in developing magnetic micro devices.

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Study on Different Synthesis Methods of Spherical YAG:Ce3+ Phosphor and its Luminescence Properties

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1088.371 ◽

2015 ◽

Vol 1088 ◽

pp. 371-376 ◽

Cited By ~ 1

Author(s):

Xia Zhang ◽

Cui Xia Yan ◽

Rong Feng Guan

Keyword(s):

Sol Gel ◽

Spherical Particles ◽

Luminescence Properties ◽

Precipitation Method ◽

Thermal Method ◽

Synthesis Methods ◽

Processing Parameter ◽

Gel Method ◽

Sol Gel Method ◽

Co Precipitation

Spherical YAG:Ce3+phosphors were synthesized by three different routes namely sol-gel method, co-precipitation method and solvethermal method. The microstructure, crystallization and luminescent properties of the phosphors were studied in order to find the best processing parameter for spherical shape and good luminescence properties of YAG:Ce3+phosphor. Adding citric acid to the precursor solution resulted in the formation of spherical particles in sol-gel method. YAG:Ce3+phosphor made by co-precipitation method was separated with PEG2000, and its spherical particles of size was around 500nm. The hydro-thermal method could get perfect spherical appearance, but it needed heat treatment improve the luminescence property.

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Synthesis Methods of Obtaining Materials for Hydrogen Sensors

Sensors ◽

10.3390/s21175758 ◽

2021 ◽

Vol 21 (17) ◽

pp. 5758

Author(s):

Izabela Constantinoiu ◽

Cristian Viespe

Keyword(s):

Spin Coating ◽

Sol Gel ◽

Synthesis Method ◽

Pulsed Laser ◽

Laser Deposition ◽

Synthesis Methods ◽

Sensitive Area ◽

Hydrogen Sensors ◽

Hydrogen Detection ◽

Co Precipitation

The development of hydrogen sensors has acquired a great interest from researchers for safety in fields such as chemical industry, metallurgy, pharmaceutics or power generation, as well as due to hydrogen’s introduction as fuel in vehicles. Several types of sensors have been developed for hydrogen detection, including resistive, surface acoustic wave, optical or conductometric sensors. The properties of the material of the sensitive area of the sensor are of great importance for establishing its performance. Besides the nature of the material, an important role for its final properties is played by the synthesis method used and the parameters used during the synthesis. The present paper highlights recent results in the field of hydrogen detection, obtained using four of the well-known synthesis and deposition methods: sol-gel, co-precipitation, spin-coating and pulsed laser deposition (PLD). Sensors with very good results have been achieved by these methods, which gives an encouraging perspective for their use in obtaining commercial hydrogen sensors and their application in common areas for society.

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In Situ Synthesis of a Stable Fe3O4@Cellulose Nanocomposite for Efficient Catalytic Degradation of Methylene Blue

Nanomaterials ◽

10.3390/nano9020275 ◽

2019 ◽

Vol 9 (2) ◽

pp. 275 ◽

Cited By ~ 9

Author(s):

Quan Lu ◽

Yanjuan Zhang ◽

Huayu Hu ◽

Wen Wang ◽

Zuqiang Huang ◽

...

Keyword(s):

Methylene Blue ◽

Fe3o4 Nanoparticles ◽

Catalytic Performance ◽

Catalytic Degradation ◽

Precipitation Method ◽

Regenerated Cellulose ◽

Practical Applications ◽

Fenton Catalyst ◽

Co Precipitation

To rapidly obtain a stable Fe3O4@cellulose heterogeneous Fenton catalyst, a novel in situ chemical co-precipitation method was developed. Compared with mechanical activation (MA)-pretreated cellulose (MAC), MA + FeCl3 (MAFC)-pretreated cellulose (MAFCC) was more easily dissolved and uniformly distributed in NaOH/urea solvent. MAFCC and MAC solutions were used as precipitators to prepare Fe3O4@MAFCC and Fe3O4@MAC nanocomposites, respectively. MAFCC showed stronger interaction and more uniform combination with Fe3O4 nanoparticles than MAC, implying that MAFC pretreatment enhanced the accessibility, reactivity, and dissolving capacity of cellulose thus, provided reactive sites for the in situ growth of Fe3O4 nanoparticles on the regenerated cellulose. Additionally, the catalytic performance of Fe3O4@MAFCC nanocomposite was evaluated by using for catalytic degradation of methylene blue (MB), and Fe3O4@MAC nanocomposite and Fe3O4 nanoparticles were used for comparative studies. Fe3O4@MAFCC nanocomposite exhibited superior catalytic activity for the degradation and mineralization of MB in practical applications. After ten cycles, the structure of Fe3O4@MAFCC nanocomposite was not significantly changed owing to the strong interaction between MAFCC and Fe3O4 nanoparticles. This study provides a green pathway to the fabrication of a stable nanocomposite catalyst with high catalytic performance and reusability for the degradation of organic pollutants.

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Innovative Synthesis Methods of Mixed Actinides Compounds with Control of the Composition Homogeneity at a Molecular or Nanometric Scale

MRS Proceedings ◽

10.1557/proc-0893-jj08-03 ◽

2005 ◽

Vol 893 ◽

Cited By ~ 1

Author(s):

Stephane Grandjean ◽

Chapelet-Arab Bénédicte ◽

Lemonnier Stéphane ◽

Robisson Anne-Charlotte ◽

Vigier Nicolas

Keyword(s):

Thermal Treatment ◽

Sol Gel ◽

3D Structure ◽

Molar Ratio ◽

Synthesis Methods ◽

Oxalate Precursor ◽

Fuel Cycles ◽

Tetravalent Actinide ◽

Sol Gel Transition ◽

Co Precipitation

AbstractActinides contained in the used nuclear fuel need to be managed in the future fuel cycles for the sustainability of this source of energy. The major ones such as uranium or plutonium are very valuable for energy production within a new fuel. The minor ones such as neptunium, americium or curium are responsible for the long-term radiotoxicity of the ultimate waste if not separated and transmuted within new fuels or dedicated targets. Whatever the choice of management in the present or future, innovative synthesis methods are studied in many research institutions to elaborate new actinides based materials.Innovative concepts for future fuels or transmutation targets focus on mixed actinides or mixed actinide-inert element materials. For their synthesis, wet methods fulfill very useful requirements such as flexibility, compatibility with a hydrometallurgical fuel processing, less dissemination of radioactive dusts during processing, and above all a better accessibility to very homogeneous compounds and interesting nanostructures. When dealing with plutonium or minor actinides, this last characteristic is of great importance in order to avoid the so-called “hot spots” and to limit macroscopic defects in the fuel material.In this communication, experimental results are given to illustrate interesting achievements to control the composition or the structure of mixed actinides compounds at a molecular or at a nanometric scale using co-precipitating techniques or sol-gel methods.The first illustration describes the flexibility of the oxalate ligand to modulate the nanostructure of actinides-based solid precursors and obtain mixed actinides oxide following a thermal treatment of the oxalate precursor. New mixed oxalate structures which present original features such as accepting in the same crystallographic site either a tetravalent actinide or a trivalent one are noticeably detailed. Monocharged cations equilibrate the charge in the 3D structure depending on the molar ratio of trivalent to tetravalent actinides. These oxalate compounds are particularly suitable precursors of oxide solid solutions for various actinides systems.The second illustration deals with the control of inorganic condensation reactions of tri- and tetravalent cations in solution by using suitable ligands with a view to obtaining homogeneous oxy-hydroxyde mixtures. The results obtained using Zr(IV), Y(III) and Am(III) or Nd(III) are quite original: a very stable colloidal sol is obtained at pH 5-6 and a nanostructured mixed oxy-hydroxide phase is formed by adapting the sol-gel transition conditions. The initial interactions between the oxy-hydroxide Zr nanoparticles, the ligand and the trivalent cations at a nanometric scale in the sol give access, after gel formation and thermal treatment, to a crystallized phase (Am-bearing cubic Y-stabilized Zirconia) at comparatively low temperatures.In both cases, the simultaneous co-precipitation or co-gelation of the involved actinides remains a challenge because of the specific properties of each actinide, properties which moreover differ according to various possible oxidation states.

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Comparative studies on impact of synthesis methods on structural and magnetic properties of magnesium ferrite nanoparticles

Processing and Application of Ceramics ◽

10.2298/pac1403137k ◽

2014 ◽

Vol 8 (3) ◽

pp. 137-143 ◽

Cited By ~ 31

Author(s):

Navneet Kaur ◽

Manpreet Kaur

Keyword(s):

Sol Gel ◽

Thermolysis Product ◽

Ferrite Nanoparticles ◽

Precipitation Method ◽

Synthesis Methods ◽

Magnesium Ferrite ◽

Solution Combustion ◽

Magnetic Parameters ◽

Physical Density ◽

Co Precipitation

Magnesium ferrite nanoparticles (NPs) were synthesized by co-precipitation, sol-gel and solution combustion methods. Polyethylene glycol (PEG), urea and oxalyl dihydrazide (ODH) were used as fuels for the combustion. Various physicochemical techniques viz. X-ray diffraction (XRD), vibrating sample magnetometry (VSM), Fourier transform infrared spectroscopy (FT-IR), BET surface analysis and transmission electron microscopy (TEM) were utilized to study the effect of synthetic methodology on the properties of synthesized NPs. Differences in crystallinity, surface area, particle size and magnetic parameters of the ferrite NPs synthesized by different methods were observed. XRD pattern of NPs obtained by sol-gel and combustion methods confirmed phase purity where as in co-precipitation method ?-Fe2O3 was detected as impurity phase which also resulted in greater value of physical density and lowering of magnetic parameters of the final thermolysis product. TEM micrographs indicated that ferrite NPs are spherical with average diameter of 12-25 nm. Presence of rectangular shaped crystallites of ?-Fe2O3 was clearly evident in the TEM images of the NPs synthesized by co-precipitation method.

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An overview of the synthesis of CuO-ZnO nanocomposite for environmental and other applications

Nanotechnology Reviews ◽

10.1515/ntrev-2017-0144 ◽

2018 ◽

Vol 7 (3) ◽

pp. 267-282 ◽

Cited By ~ 22

Author(s):

Susmita Das ◽

Vimal Chandra Srivastava

Keyword(s):

Metal Oxide ◽

Environmental Science ◽

Mixed Oxides ◽

Sol Gel ◽

Metal Oxide Semiconductor ◽

Oxide Semiconductor ◽

Wet Impregnation ◽

Practical Applications ◽

Wide Range ◽

Co Precipitation

Abstract In the field of environmental science, metal oxide nanocomposites have gained a great attention for both theoretical and experimental aspects of their upgradation because of their wide range of practical applications such as catalysts, sensors, hydrogen storages, and optoelectronics. Among all nanocomposites, Copper oxide-zinc oxide (CuO-ZnO) has attracted more research due to their excellent tunable catalytic, electrical, optical, and magnetic properties and environment-friendly nature. Coupling of one metal oxide semiconductor with another metal oxide semiconductor produces an enlarged surface area, which provide more reactive sites, promotes mass transfer, promotes electron transfer, and avoids photo-corrosion of nanocomposites, which enhances its efficiency. The CuO-ZnO nanocomposite has been prepared by various methods such as co-precipitation, sol-gel, wet impregnation, and thermal decomposition. Depending on the preparation method and conditions used, different types of CuO-ZnO nanocomposites like Cu-doped ZnO, Cu supported/impregnated on ZnO, and CuO-ZnO mixed oxides with different morphologies of CuO-ZnO nanocomposites have been obtained. This article reviews the synthesis techniques of the CuO-ZnO nanocomposite and its morphology. Various practical applications of the CuO-ZnO nanocomposites have also been discussed.

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Effect of Silica Promoter on Performance of CuO-ZnO-ZrO2 Catalyst for Methanol Synthesis from CO2 Hydrogenation

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.556-562.117 ◽

2014 ◽

Vol 556-562 ◽

pp. 117-122 ◽

Cited By ~ 4

Author(s):

Miao Yao Jia ◽

Wen Gui Gao ◽

Hua Wang ◽

Yu Hao Wang

Keyword(s):

Catalytic Activity ◽

Specific Surface ◽

Surface Area ◽

Methanol Synthesis ◽

Catalytic Properties ◽

Catalytic Performance ◽

Precipitation Method ◽

Test Results ◽

Excellent Performance ◽

Co Precipitation

Various CuO-ZnO-ZrO2(CZZ) catalysts for methanol synthesis from CO2 hydrogenation were prepared by co-precipitation method. Small amount of silica was incorporated into CZZ catalyst to produce these modified ternary CZZ catalysts. The effects of silica on physicochemical and catalytic properties were studied by TG-DTG,XRD,BET,N2O chemisorption,H2-TPR,NH3-TPD and CO2-TPD techniques. The results show that the properties of catalysts were strongly influenced by the content of SiO2 used as promoter. The catalytic performance for methanol synthesis from CO2 hydrogenation was evaluated. The test results show that the CZZ catalyst modified with 4 wt.% SiO2 exhibits an optimum catalytic activity. The silica improves the dispersion of CuO and its modified CZZ catalysts exhibits higher specific surface area, which were confirmed to be responsible for excellent performance of the catalysts for methanol synthesis from CO2 hydrogenation.

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Investigation and Preparation of the SCR Catalysts Nano-Co/Ce-V-Zr-TiO2

Materials Science Forum ◽

10.4028/www.scientific.net/msf.663-665.1097 ◽

2010 ◽

Vol 663-665 ◽

pp. 1097-1102

Author(s):

Xiu Feng Ren ◽

Fen Wang ◽

Yuan Zhou ◽

Hong En Nian ◽

Yu Na Pang ◽

...

Keyword(s):

Reaction Temperature ◽

Catalytic Reduction ◽

Sol Gel ◽

Selective Reduction ◽

Catalytic Performance ◽

Scr Catalysts ◽

Selective Reduction Of Nox ◽

Reduction Of Nox ◽

Co Precipitation ◽

Catalytic Performances

The nano-Co/Ce-V-Zr-TiO2 catalysts with the selective catalytic reduction (SCR) were prepared by methods of Sol-gel, impregnation (IM) and co-precipitation (CP). The phase compositions, microstructures and specific surface area of the catalysts were analyzed by BET, XRD and SEM, respectively. The effect of CeO2, CoO, V2O5 and V2O5 loading and reaction temperature on the catalytic performances of the as-prepared catalysts was investigated by using the selective reduction of NOx with NH3. The results showed all the as-prepared Co/Ce-V-Zr-TiO2 catalysts were made up of nanometer grains. Compared to conventional TiO2 catalysts, the as-prepared Co/Ce-V-Zr-TiO2 catalysts possessed better catalytic performance, higher adsorbability and larger area of contact with reactant, which is due to large quantity surface micropores. The NOx conversion of SCR over 8 wt%Co/Ce-V-Zr-TiO2 catalysts reached 98.3% at the reaction temperature of 550 oC. Furthermore, the activity of Co/Ce-V-Zr-TiO2 catalysts were improved by the Co loading, however, further increasing the Co loading lead to decrease the catalysis activity.

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Study of Polyethers/Lii Systems by Addition of Alumina Ceramic Powders Prepared by Two Synthesis Methods

MRS Proceedings ◽

10.1557/proc-548-383 ◽

1998 ◽

Vol 548 ◽

Author(s):

R. A. Ribeiro ◽

G. G. Silva ◽

N. D. S. Mohallem

Keyword(s):

Sol Gel ◽

Alumina Ceramic ◽

Synthesis Methods ◽

Ceramic Powders ◽

Scanning Calorimetry ◽

Dsc Studies ◽

Lower Melting Point ◽

Poly Ethylene ◽

Copolymer Poly ◽

Co Precipitation

ABSTRACTComposites of alumina ceramic powders prepared by co-precipitation and sol-gel methods with Lithium Iodide based polymer electrolytes are described. The polyether matrices Poly(ethylene oxide) (PEO) and block copolymer Poly(propylene glycol-ethylene glycolpropylene glycol) (Triblock) with Lil in a ratio [O]:[Li] = 20:1 are used with up to 17 wt% of α-A1203 (medium grain size). Differential Scanning Calorimetry (DSC) studies show that Tg values for PEO based composites are higher whereas those for Triblock based composites are lower than the Tg value of the polymer/salt system.Conductivity measurements as a function of temperature show that there is no significant change in conductivity above the melting points for the electrolytes after α-A1203 powder addition (σ approximately 10−3 S.cm−l at 100°C), whereas better mechanical properties are observed for the ceramic reinforced samples. An increase in conductivity is obtained for the Triblock based composites near room temperature as a consequence of the lower melting point of these materials (26°C) in comparison to the PEO based composites (54°C).

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