Materials

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15 pages, 2998 KiB

Open AccessEditor’s ChoiceArticle

Functional Evaluation of 3D Liver Models Labeled with Polysaccharide Functionalized Magnetic Nanoparticles

by Yoshitaka Miyamoto, Yumie Koshidaka, Katsutoshi Murase, Shoichiro Kanno, Hirofumi Noguchi, Kenji Miyado, Takeshi Ikeya, Satoshi Suzuki, Tohru Yagi, Naozumi Teramoto and Shuji Hayashi

Materials 2022, 15(21), 7823; https://doi.org/10.3390/ma15217823 - 5 Nov 2022

Cited by 2 | Viewed by 2553

Abstract

Establishing a rapid in vitro evaluation system for drug screening is essential for the development of new drugs. To reproduce tissues/organs with functions closer to living organisms, in vitro three-dimensional (3D) culture evaluation using microfabrication technology has been reported in recent years. Culture [...] Read more.

Establishing a rapid in vitro evaluation system for drug screening is essential for the development of new drugs. To reproduce tissues/organs with functions closer to living organisms, in vitro three-dimensional (3D) culture evaluation using microfabrication technology has been reported in recent years. Culture on patterned substrates with controlled hydrophilic and hydrophobic regions (Cell-able^TM) can create 3D liver models (miniature livers) with liver-specific Disse luminal structures and functions. MRI contrast agents are widely used as safe and minimally invasive diagnostic methods. We focused on anionic polysaccharide magnetic iron oxide nanoparticles (Resovist^®) and synthesized the four types of nanoparticle derivatives with different properties. Cationic nanoparticles (TMADM) can be used to label target cells in a short time and have been successfully visualized in vivo. In this study, we examined the morphology of various nanoparticles. The morphology of various nanoparticles showed relatively smooth-edged spherical shapes. As 3D liver models, we prepared primary hepatocyte–endothelial cell heterospheroids. The toxicity, CYP3A, and albumin secretory capacity were evaluated in the heterospheroids labeled with various nanoparticles. As the culture period progressed, the heterospheroids labeled with anionic and cationic nanoparticles showed lower liver function than non-labeled heterospheroids. In the future, there is a need to improve the method of creation of artificial 3D liver or to design a low-invasive MRI contrast agent to label the artificial 3D liver. Full article

(This article belongs to the Special Issue Synthesis and Applications of Nanoparticles)

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14 pages, 4430 KiB

Open AccessArticle

Solvothermal Synthesis, Structural Characterization and Optical Properties of Pr-Doped CeO₂ and Their Degradation for Acid Orange 7

by Yaohui Xu, Pingkeng Wu, Mingjin Wu, Yuehe Gu, Hongguang Yu and Zhao Ding

Materials 2022, 15(19), 6953; https://doi.org/10.3390/ma15196953 - 7 Oct 2022

Cited by 2 | Viewed by 1647

Abstract

Pr-doped CeO₂ with different doping levels was prepared from Ce(NO₃)₃∙6H₂O and Pr(NO₃)₃∙6H₂O by solvothermal method without any additional reagents, in which the mixed solution of ethylene glycol and distilled water [...] Read more.

Pr-doped CeO₂ with different doping levels was prepared from Ce(NO₃)₃∙6H₂O and Pr(NO₃)₃∙6H₂O by solvothermal method without any additional reagents, in which the mixed solution of ethylene glycol and distilled water was employed as a solvent. The influences of Pr-doping on phase composition, crystal structure and morphology were investigated, as well as Pr valence and oxygen vacancy defects. The Pr cations entered into the CeO₂ crystal lattice with normal trivalence and formed a Pr-CeO₂ solid solution based on the fluorite structure. The larger trivalent Pr was substituted for tetravalent Ce in the CeO₂ crystal and compensated by oxygen vacancy defects, which caused the local lattice expansion of the crystal lattice. Moreover, the Pr-doped CeO₂ solid solutions exhibited visible color variation from bright cream via brick red to dark brown with the increasing of Pr contents. The degradation of AO7 dye was also investigated using a domestic medical ultraviolet lamp; the removal efficiency of AO7 by 1% and 2% Pr-doped CeO₂ approached 100%, much higher than 66.2% for undoped CeO₂. Full article

(This article belongs to the Special Issue Synthesis and Applications of Nanoparticles)

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20 pages, 4382 KiB

Open AccessArticle

Experimental and Computational Study of Novel Pyrazole Azo Dyes as Colored Materials for Light Color Paints

by Sabina Nitu, Marius Silviu Milea, Sorina Boran, Giannin Mosoarca, Alina D. Zamfir, Simona Popa and Simona Funar-Timofei

Materials 2022, 15(16), 5507; https://doi.org/10.3390/ma15165507 - 11 Aug 2022

Cited by 6 | Viewed by 2275

Abstract

This paper presents the synthesis of eight new pyrazole azo dyes using ethyl 5-amino-3-methyl-1H-pyrazole-4-carboxylate as the diazotization component and various active methylene derivatives as coupling components. These new azo dyes were characterized by spectroscopic (FT-IR, UV-VIS), and spectrometric (¹H [...] Read more.

This paper presents the synthesis of eight new pyrazole azo dyes using ethyl 5-amino-3-methyl-1H-pyrazole-4-carboxylate as the diazotization component and various active methylene derivatives as coupling components. These new azo dyes were characterized by spectroscopic (FT-IR, UV-VIS), and spectrometric (¹H NMR, ¹³C NMR, MS) analyses. The dye structures were modeled by the MMFF94s force field and quantum chemical density functional theory (DFT) calculations using the B3LYP functional and the 6-311G(d,p) basis set, in the gas phase. Weak electrostatic hydrogen bonds for the azo and hydrazo dye tautomers were found in the ground state. The CIS, TD (using the B3LYP and M06-2X functionals), and ZINDO methods were used to estimate the dye UV-VIS spectra in ethanol, which were compared with the experimental ones. The anti-configuration arrangement of the π-bonds and the presence of the prevalent hydrazo dye tautomer were supported by the computed ¹H NMR and ¹³C NMR spectra. A good accordance between the experimental and predicted absorption maxima and chemical shifts was observed. Color investigations using the CIEL*a*b* space were conducted for all dyes in powder and for their mixtures in water-based acrylic resins. The results confirm the newly synthesized dyes’ color properties and that they might be used for light color paints in the varnishes industry. Full article

(This article belongs to the Special Issue Synthesis and Applications of Nanoparticles)

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12 pages, 1493 KiB

Open AccessArticle

Onion Peel Waste Mediated-Green Synthesis of Zinc Oxide Nanoparticles and Their Phytotoxicity on Mung Bean and Wheat Plant Growth

by Shreya Modi, Virendra Kumar Yadav, Nisha Choudhary, Abdullah M. Alswieleh, Anish Kumar Sharma, Abhishek Kumar Bhardwaj, Samreen Heena Khan, Krishna Kumar Yadav, Ji-Kwang Cheon and Byong-Hun Jeon

Materials 2022, 15(7), 2393; https://doi.org/10.3390/ma15072393 - 24 Mar 2022

Cited by 39 | Viewed by 4870

Abstract

Nanoparticles and nanomaterials have gained a huge amount of attention in the last decade due to their unique and remarkable properties. Metallic nanoparticles like zinc oxide nanoparticles (ZnONPs) have been used very widely as plant nutrients and in wastewater treatment. Here, ZnONPs were [...] Read more.

Nanoparticles and nanomaterials have gained a huge amount of attention in the last decade due to their unique and remarkable properties. Metallic nanoparticles like zinc oxide nanoparticles (ZnONPs) have been used very widely as plant nutrients and in wastewater treatment. Here, ZnONPs were synthesized by using onion peel and characterized by various sophisticated instruments like Fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), and field emission scanning electron microscopes (FESEM). FTIR confirmed ZnONPs synthesis due to the formation of the band in the region of 400–800 cm⁻¹, while FESEM confirmed the spherical shape of the particles whose size varies in the range of 20–80 nm. FTIR revealed several bands from 1000–1800 cm⁻¹ which indicates the capping by the organic molecules on the ZnONPs, which came from onion peel. It also has carbonyl and hydroxyl groups, due to the organic molecules present in the Allium cepa peel waste. The average hydrodynamic size of ZnONPs was 500 nm as confirmed by DLS. The synthesized ZnONPs were then used as a plant nutrient where their effect was evaluated on the growth of Vigna radiate (mung bean) and Triticum aestivum (wheat seeds). The results revealed that the germination and seedling of mung and wheat seeds with ZnONPs were grown better than the control seed. However, seeds of mung and wheat with ZnONPs at median concentration exposure showed an enhancement in percent germination, root, and shoot length in comparison to control. Thus, the effect of ZnONPs has been proved as a nano-based nutrient source for agricultural purposes. Full article

(This article belongs to the Special Issue Synthesis and Applications of Nanoparticles)

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19 pages, 4545 KiB

Open AccessArticle

Laboratory Evaluation of Mechanical Properties of Modified Asphalt and Mixture Using Graphene Platelets (GnPs)

by Mohamed Samir Eisa, Ahmed Mohamady, Mohamed E. Basiouny, Ayman Abdulhamid and Jong R. Kim

Materials 2021, 14(19), 5599; https://doi.org/10.3390/ma14195599 - 27 Sep 2021

Cited by 12 | Viewed by 3107

Abstract

Recently, nanomaterials have attracted attention in the field of pavement construction as modifiers to endure heavy loads and climate changes. In this study, conventional asphalt (bitumen) of penetration grade AC (60/70) was modified with graphene platelets (GnPs) at three different contents: 0.5%, 1.0%, [...] Read more.

Recently, nanomaterials have attracted attention in the field of pavement construction as modifiers to endure heavy loads and climate changes. In this study, conventional asphalt (bitumen) of penetration grade AC (60/70) was modified with graphene platelets (GnPs) at three different contents: 0.5%, 1.0%, and 1.5% by weight of asphalt content. Kinematic viscosity, softening point, penetration, and dynamic shear rheology tests were performed to evaluate the mechanical properties of modified binder. The results showed that adding GnPs improves the mechanical properties of asphalt binder; the kinematic viscosities, softening points, and rutting parameters increased but penetrations decreased with the contents of GnPs. Hot mix asphalt specimens with GnPs-modified asphalt were prepared and characterized with Marshall tests, thermal stress restrained specimen tests (TSRST), wheel tracking tests, and indirect tensile tests. Similar to the results of asphalt binder, the mechanical properties of asphalt mixture were improved by GnPs. Marshall stability increased by 21% and flow decreased by 24% with accepted value of 2.8 mm in penetration when the mixture was modified with 1.0 wt% of GnPs. At the same GnPs content, modified asphalt mixture led to lower failure temperature by 2 °C in comparison with unmodified asphalt mixture and the cryogenic failure stress was improved by 12%. The wheel tracking tests showed that GnPs-modified asphalt mixture has outstanding deformation resistance in comparison with unmodified asphalt mixtures: after 5000 cycles, 1.0 wt% of GnPs reduced the rut depth of asphalt mixture by 60%—the rut depth of unmodified asphalt mixture was 6.9 mm compared to 2.75 mm for modified asphalt mixture. After 10,000 cycles, the modified asphalt mixture showed rut depth of 3.24 mm in comparison with 8.12 mm in case of unmodified asphalt mixture. Addition of GnPs into asphalt mixture significantly improved the indirect tensile strength: 1.0 wt% of GnPs increased the indirect tensile strength of unmodified asphalt mixture from 0.79 to 1.1 MPa recording ~40% increment. The results of this study can confirm that graphene platelets enhance the mechanical properties of asphalt mixture and its performance. Full article

(This article belongs to the Special Issue Synthesis and Applications of Nanoparticles)

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21 pages, 12403 KiB

Open AccessArticle

Polystyrene-Fe₃O₄-MWCNTs Nanocomposites for Toluene Removal from Water

by Thamer Adnan Abdullah, Tatjána Juzsakova, Rashed Taleb Rasheed, Ali Dawood Salman, Viktor Sebestyen, Endre Domokos, Brindusa Sluser and Igor Cretescu

Materials 2021, 14(19), 5503; https://doi.org/10.3390/ma14195503 - 23 Sep 2021

Cited by 11 | Viewed by 2537

Abstract

In this research, multi-walled carbon nanotubes (MWCNTs) were functionalized by oxidation with strong acids HNO₃, H₂SO₄, and H₂O₂. Then, magnetite/MWCNTs nanocomposites were prepared and polystyrene was added to prepare polystyrene/MWCNTs/magnetite (PS:MWCNTs:Fe) nanocomposites. The [...] Read more.

In this research, multi-walled carbon nanotubes (MWCNTs) were functionalized by oxidation with strong acids HNO₃, H₂SO₄, and H₂O₂. Then, magnetite/MWCNTs nanocomposites were prepared and polystyrene was added to prepare polystyrene/MWCNTs/magnetite (PS:MWCNTs:Fe) nanocomposites. The magnetic property of the prepared nano-adsorbent PS:MWCNTs:Fe was successfully checked. For characterization, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and BET surface area were used to determine the structure, morphology, chemical nature, functional groups, and surface area with pore volume of the prepared nano-adsorbents. The adsorption procedures were carried out for fresh MWCNTs, oxidized MWCNTs, MWCNTs-Fe, and PS:MWCNTs:Fe nanocomposites in batch experiments. Toluene standard was used to develop the calibration curve. The results of toluene adsorption experiments exhibited that the PS:MWCNTs:Fe nonabsorbent achieved the highest removal efficiency and adsorption capacity of toluene removal. The optimum parameters for toluene removal from water were found to be 60 min, 2 mg nano-sorbent dose, pH of 5, solution temperature of 35 °C at 50 mL volume, toluene concentration of 50 mg/L, and shaking speed of 240 rpm. The adsorption kinetic study of toluene followed the pseudo-second-order kinetics, with the best correlation (R²) value of 0.998, while the equilibrium adsorption study showed that the Langmuir isotherm was obeyed, which suggested that the adsorption is a monolayer and homogenous. Full article

(This article belongs to the Special Issue Synthesis and Applications of Nanoparticles)

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21 pages, 40379 KiB

Open AccessArticle

Chemical and Structural Changes by Gold Addition Using Recharge Method in NiW/Al₂O₃-CeO₂-TiO₂ Nanomaterials

by Jorge Cortez-Elizalde, Ignacio Cuauhtémoc-López, Zenaida Guerra-Que, Alejandra Elvira Espinosa de los Monteros, Ma. Antonia Lunagómez-Rocha, Adib Abiu Silahua-Pavón, Juan Carlos Arévalo-Pérez, Adrián Cordero-García, Adrián Cervantes-Uribe and José Gilberto Torres-Torres

Materials 2021, 14(19), 5470; https://doi.org/10.3390/ma14195470 - 22 Sep 2021

Cited by 2 | Viewed by 2669

Abstract

NiWAu trimetallic nanoparticles (NPs) on the surface of support Al₂O₃-CeO₂-TiO₂ were synthesized by a three-step synthetic method in which Au NPs were incorporated into presynthesized NiW/Al₂O₃-CeO₂-TiO₂. The recharge [...] Read more.

NiWAu trimetallic nanoparticles (NPs) on the surface of support Al₂O₃-CeO₂-TiO₂ were synthesized by a three-step synthetic method in which Au NPs were incorporated into presynthesized NiW/Al₂O₃-CeO₂-TiO₂. The recharge method, also known as the redox method, was used to add 2.5 wt% gold. The Al₂O₃-CeO₂-TiO₂ support was made by a sol–gel method with two different compositions, and then two metals were simultaneously loaded (5 wt% nickel and 2.5 wt% tungsten) by two different methods, incipient wet impregnation and ultrasound impregnation method. In this paper, we study the effect of Au addition using the recharge method on NiW nanomaterials supported on mixed oxides on the physicochemical properties of synthesized nanomaterials. The prepared nanomaterials were characterized by scanning electron microscopy, BET specific surface area, X-ray diffraction, diffuse reflectance spectroscopy in the UV–visible range and temperature-programmed desorption of hydrogen. The experimental results showed that after loading of gold, the dispersion was higher (46% and 50%) with the trimetallic nanomaterials synthesized by incipient wet impregnation plus recharge method than with impregnation plus ultrasound recharge method, indicating a greater number of active trimetallic (NiWAu) sites in these materials. Small-sized Au from NiWAu/ACTU1 trimetallic nanostructures was enlarged for NiWAu/ACT1. The strong metal NPs–support interaction shown for the formation of NiAl₂O₄, Ni-W-O and Ni-Au-O species simultaneously present in the surface of trimetallic nanomaterial probably plays an important role in the degree of dispersion of the gold active phase. Full article

(This article belongs to the Special Issue Synthesis and Applications of Nanoparticles)

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21 pages, 38309 KiB

Open AccessArticle

Nanocarbon Type Xerogel Materials Designed for Water Desalination

by Gabriela Hristea, Mihai Iordoc and Andreea Culcea

Materials 2021, 14(17), 4932; https://doi.org/10.3390/ma14174932 - 30 Aug 2021

Cited by 1 | Viewed by 2205

Abstract

The relative performance of different porous solids in different applications is highly dependent on the internal pore structure of each material. Highly porous carbon materials can be prepared by evaporative drying and the pyrolysis of resorcinol-formaldehyde gels. By determining the correct synthesis parameters, [...] Read more.

The relative performance of different porous solids in different applications is highly dependent on the internal pore structure of each material. Highly porous carbon materials can be prepared by evaporative drying and the pyrolysis of resorcinol-formaldehyde gels. By determining the correct synthesis parameters, the pore system of such materials can be reshaped. Depending on some important processing factors such as the dilution ratio or the initial pH of the precursor solution, various porous or non-porous carbon materials can be synthesized. This paper addresses carbon xerogels (CX) designed as a material electrode in capacitive deionization (CDI) systems for water desalination. In this work CX materials were synthesized via poly-condensation reactions of resorcinol with formaldehyde (RF) on a carbon felt sheet followed by pyrolysis. The resulting sheets were used as electrodes to develop a CDI experimental multi-cell laboratory system. The initial pH of the RF solution and the dilution ratio effect on the resulting carbon surface area and structure were analyzed. Surface area measurements using the BET method and an electrochemical capacitance evaluation of the obtained xerogels through electrochemical impedance spectroscopy were also performed. Finally, using our experimental CDI multi-cell laboratory system based on the obtained CX, we discuss the experimental data for the desalination rate as a function of the voltage and salt concentration. As a result, the developed model’s efficiency is demonstrated. The main goal of this work was to develop an efficient electrode-based novel carbon that could be commercially competitive, as well as to create guidelines for future desalination research using CX electrode materials. Full article

(This article belongs to the Special Issue Synthesis and Applications of Nanoparticles)

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17 pages, 3858 KiB

Open AccessArticle

Evaluation of the Anticancer Activity of Phytomolecules Conjugated Gold Nanoparticles Synthesized by Aqueous Extracts of Zingiber officinale (Ginger) and Nigella sativa L. Seeds (Black Cumin)

by Alaa H. Alkhathlan, Hessah A. Al-Abdulkarim, Merajuddin Khan, Mujeeb Khan, Musaed Alkholief, Aws Alshamsan, Aliyah Almomen, Norah Albekairi, Hamad Z. Alkhathlan and M. Rafiq H. Siddiqui

Materials 2021, 14(12), 3368; https://doi.org/10.3390/ma14123368 - 18 Jun 2021

Cited by 24 | Viewed by 3551

Abstract

The conventional physical and chemical synthetic methods for the preparation of metal nanoparticles have disadvantages as they use expensive equipment and hazardous chemicals which limit their applications for biomedical purposes, and are not environment friendly. However, for the synthesis of biocompatible nanomaterials, plant-based [...] Read more.

The conventional physical and chemical synthetic methods for the preparation of metal nanoparticles have disadvantages as they use expensive equipment and hazardous chemicals which limit their applications for biomedical purposes, and are not environment friendly. However, for the synthesis of biocompatible nanomaterials, plant-based techniques are eco-friendly and easy to handle. Herein a simple, single-step biosynthesis of gold nanoparticles using aqueous extracts of Nigella sativa (NSE) and Zingiber officinale (GE) as a reducing and capping agent has been demonstrated. The formation of gold nanoparticles (Au NPs) was confirmed by X-ray diffraction, UV-Vis, and EDS spectroscopies. Spectroscopic and chromatographic analysis of GE and NSE revealed the presence of bioactive phytochemical constituents, such as gingerol, thymoquinone, etc., which successfully conjugated the surface of resulting Au NPs. TEM analysis indicated the formation of smaller-sized, less-aggregated, spherical-shaped Au NPs both in the case of GE (~9 nm) and NSE (~11 nm). To study the effect of the concentration of the extracts on the quality of resulting NPs and their anticancer properties, three different samples of Au NPs were prepared from each extract by varying the concentration of extracts while keeping the amount of precursor constant. In both cases, high-quality, spherical-shaped NPs were obtained, only at a high concentration of the extract, whereas at lower concentrations, larger-sized, irregular-shaped NPs were formed. Furthermore, the as-prepared Au NPs were evaluated for the anticancer properties against two different cell lines including MDA-MB-231 (breast cancer) and HCT 116 (colorectal cancer) cell lines. GE-conjugated Au NPs obtained by using a high concentration of the extract demonstrated superior anticancer properties when compared to NSE-conjugated counterparts. Full article

(This article belongs to the Special Issue Synthesis and Applications of Nanoparticles)

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15 pages, 4221 KiB

Open AccessArticle

Novel Hybrid Nanoparticles: Synthesis, Functionalization, Characterization, and Their Application in the Uptake of Scandium (III)Ions from Aqueous Media

by Ali Dawood Salman, Tatjána Juzsakova, Moayed G. Jalhoom, Cuong Le Phuoc, Saja Mohsen, Thamer Adnan Abdullah, Balázs Zsirka, Igor Cretescu, Endre Domokos and Catalina Daniela Stan

Materials 2020, 13(24), 5727; https://doi.org/10.3390/ma13245727 - 15 Dec 2020

Cited by 12 | Viewed by 2933

Abstract

The aim of this study was to prepare novel supramolecular hybrid nanoparticles (HNPs) that can selectively separate and recover scandium metal ions, Sc(III), from an aqueous phase based on molecular recognition technology (MRT). Moreover, this approach is fully compatible with green chemistry principles. [...] Read more.

The aim of this study was to prepare novel supramolecular hybrid nanoparticles (HNPs) that can selectively separate and recover scandium metal ions, Sc(III), from an aqueous phase based on molecular recognition technology (MRT). Moreover, this approach is fully compatible with green chemistry principles. In this work, natural amorphous silica (SiO₂) nanoparticles were prepared by a precipitation method from Iraqi rice husk (RH) followed by surface modification with 3-amino-propyl triethoxysilane (APTES) as coupling agent and Kryptofix 2.2.2 (K2.2.2) as polycyclic ligand. To evaluate the potential of the hybrid nanoparticles, the prepared HNPs were used for the solid–liquid extraction of scandium, Sc(III), ions from model solutions due to the fact that K2.2.2 are polycyclic molecules. These polycyclic molecules are able to encapsulate cations according to the corresponding cavity size with the ionic radius of metal by providing a higher protection due their cage-like structures. Moreover, the authors set the objectives to design a high-technology process using these HNPs and to develop a Sc recovery method from the aqueous model solution prior to employing it in industrial applications, e.g., for Sc recovery from red mud leachate. The concentrations of Sc model solutions were investigated using the UV-Vis spectrophotometer technique. Different characterization techniques were used including scanning electron microscope (SEM), atomic force microscopy (AFM), Brunauer–Emmett–Teller (BET), X-ray diffraction (XRD), X-ray fluorescence (XRF), and Fourier transform infrared (FTIR). The extraction efficiency of Sc varied from 81.3% to 96.7%. Moreover, the complexed Sc ions were efficiently recovered by HCl with 0.1 mol/L concentration. The stripping ratios of Sc obtained ranged from 93.1% to 97.8%. Full article

(This article belongs to the Special Issue Synthesis and Applications of Nanoparticles)

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19 pages, 4260 KiB

Open AccessArticle

Zn/La Mixed Oxides Prepared by Coprecipitation: Synthesis, Characterization and Photocatalytic Studies

by Amalia Maria Sescu, Maria Harja, Lidia Favier, Laurence Oughebbi Berthou, Consuelo Gomez de Castro, Aurel Pui and Doina Lutic

Materials 2020, 13(21), 4916; https://doi.org/10.3390/ma13214916 - 31 Oct 2020

Cited by 15 | Viewed by 3856

Abstract

Mixed oxides containing zinc and lanthanum were prepared by coprecipitation in alkaline medium, followed by calcination at 400 °C. The initial precipitation product and the calcined form were characterized by Brunauer–Emmett–Teller (BET) method adsorption of nitrogen at −196 °C, Scanning Electron Microscopy/Electron-Probe Microanalysis [...] Read more.

Mixed oxides containing zinc and lanthanum were prepared by coprecipitation in alkaline medium, followed by calcination at 400 °C. The initial precipitation product and the calcined form were characterized by Brunauer–Emmett–Teller (BET) method adsorption of nitrogen at −196 °C, Scanning Electron Microscopy/Electron-Probe Microanalysis (SEM/EPM), Ultraviolet—Diffuse Reflectance Spectroscopy (UV-DRS) and Infrared (IR) spectroscopy. The band gap slightly changes from 3.23 eV to 3 eV by calcination. The photocatalytic performance of the solids were investigated in diluted aqueous medium, by using clofibric acid (CA), a stable and toxic molecule used as precursor in some pesticides and drugs, as test compound, possibly found in the wastewaters in low concentrations. The effects of the degradation extent, determined by high performance liquid chromatography (HPLC) and total organic carbon (TOC) measurements, were investigated at different initial concentrations of CA. Within about 60 min the CA degradation is almost total at low concentration values (3 ppm) and reaches over 80% in 180 min for an initial concentration of 50 ppm. Moreover, the CA removal performance of photocatalyst remains excellent after three cycles of use: the removal yield was practically total after 60 min in the first two cycles and reached 95% even in the third cycle. Full article

(This article belongs to the Special Issue Synthesis and Applications of Nanoparticles)

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20 pages, 10461 KiB

Open AccessArticle

Comparison of Gold Nanoparticles Deposition Methods and Their Influence on Electrochemical and Adsorption Properties of Titanium Dioxide Nanotubes

by Ewa Paradowska, Katarzyna Arkusz and Dorota G. Pijanowska

Materials 2020, 13(19), 4269; https://doi.org/10.3390/ma13194269 - 25 Sep 2020

Cited by 21 | Viewed by 3309

Abstract

The increasing interest of attachment of gold nanoparticles (AuNPs) on titanium dioxide nanotubes (TNTs) has been devoted to obtaining tremendous properties suitable for biosensor applications. Achieving precise control of the attachment and shape of AuNPs by methods described in the literature are far [...] Read more.

The increasing interest of attachment of gold nanoparticles (AuNPs) on titanium dioxide nanotubes (TNTs) has been devoted to obtaining tremendous properties suitable for biosensor applications. Achieving precise control of the attachment and shape of AuNPs by methods described in the literature are far from satisfactory. This work shows the comparison of physical adsorption (PA), cyclic voltammetry (CV) and chronoamperometry (CA) methods and the parameters of these methods on TNTs properties. The structural, chemical, phase and electrochemical characterizations of TNTs, Au/TNTs, AuNPs/TNTs are carried out using scanning electron microscopy (SEM), electrochemical impedance spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy. The use of PA methods does not allow the deposition of AuNPs on TNTs. CV allows easily obtaining spherical nanoparticles, for which the diameter increases from 20.3 ± 2.9 nm to 182.3 ± 51.7 nm as a concentration of tetrachloroauric acid solution increase from 0.1 mM to 10 mM. Increasing the AuNPs deposition time in the CA method increases the amount of gold, but the AuNPs diameter does not change (35.0 ± 5 nm). Importantly, the CA method also causes the dissolution of the nanotubes layer from 1000 ± 10.0 nm to 823 ± 15.3 nm. Modification of titanium dioxide nanotubes with gold nanoparticles improved the electron transfer and increased the corrosion resistance, as well as promoted the protein adsorption. Importantly, after the deposition of bovine serum albumin, an almost 5.5-fold (324%) increase in real impedance, compared to TNTs (59%) was observed. We found that the Au nanoparticles—especially those with smaller diameter—promoted the stability of bovine serum albumin binding to the TNTs platform. It confirms that the modification of TNTs with gold nanoparticles allows the development of the best platform for biosensing applications. Full article

(This article belongs to the Special Issue Synthesis and Applications of Nanoparticles)

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11 pages, 3412 KiB

Open AccessArticle

Dual-Responsive Nanotubes Assembled by Amphiphilic Dendrimers: Controlled Release and Crosslinking

by Minghui Zhang, Hui Yang, Jiazhong Wu, Siyu Yang, Danfeng Yu, Xu Wu, Aiqing Ma, Keji Sun and Jinben Wang

Materials 2020, 13(16), 3479; https://doi.org/10.3390/ma13163479 - 7 Aug 2020

Viewed by 1994

Abstract

Although stimuli-responsive release systems have attracted great attention in medical applications, there has been no attempt at “precise” deep profile control based on such systems, which is greatly need to improve oil recovery. With this in mind, we provided a facile and simple [...] Read more.

Although stimuli-responsive release systems have attracted great attention in medical applications, there has been no attempt at “precise” deep profile control based on such systems, which is greatly need to improve oil recovery. With this in mind, we provided a facile and simple strategy to prepare stimuli-responsive composite capsules of amphiphilic dendrimers–poly(styrene sulfonic acid) sodium/halloysite nanotubes (HNTs) via layer-by-layer (LbL) self-assembly technique, controlling the release crosslinking agent methenamine under different pH or salinity conditions. The release time of methenamine encapsulated in multilayer shells is about 40 h, which can be prolonged with the introduction of salt or shortened via the addition of acid, which accordingly induces the gelation of polyacrylamide (PAM) solutions, taking from a few hours to a dozen days. This study provided a novel approach for controllable release of chemical agents and controllable crosslinking of deep profiles in many application fields. Full article

(This article belongs to the Special Issue Synthesis and Applications of Nanoparticles)

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15 pages, 6539 KiB

Open AccessArticle

Enhanced Microwave Absorption and Electromagnetic Properties of Si-Modified rGO@Fe₃O₄/PVDF-co-HFP Composites

by Yuexuan Li, Yugang Duan and Chengmeng Wang

Materials 2020, 13(4), 933; https://doi.org/10.3390/ma13040933 - 20 Feb 2020

Cited by 16 | Viewed by 3143

Abstract

Graphene has been regarded as one of the most promising two-dimensional nanomaterials. Even so, graphene was still faced with several key issues such as impedance mismatching and narrow bandwidth, which have hindered the practical applications of graphene-based nanocomposites in the field of microwave [...] Read more.

Graphene has been regarded as one of the most promising two-dimensional nanomaterials. Even so, graphene was still faced with several key issues such as impedance mismatching and narrow bandwidth, which have hindered the practical applications of graphene-based nanocomposites in the field of microwave absorption materials. Herein, a series of Si-modified rGO@Fe₃O₄ composites were investigated and fabricated by a simple method. On one hand, the degree of defects in graphene carbon could be tuned by different silane coupling reagents, which were beneficial to enhancing the dielectric loss. On the other hand, the spherical Fe₃O₄ nanoparticles provided the magnetic loss resonance, which contributed to controlling the impedance matching. Subsequently, the electromagnetic absorption (EMA) properties of Si-modified rGO@Fe₃O₄ composites with poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-co-HFP) were investigated in this work. As a result, the Si(2)-rGO@Fe₃O₄/PVDF-co-HFP composite exhibited the excellent EMA performance in the range of 2–18 GHz. The maximum reflection loss (RL_max) reached −32.1 dB at 3.68 GHz at the thickness of 7 mm and the effective absorption frequency bandwidth for reflection loss (RL) below −10 dB was 4.8 GHz at the thickness of 2 mm. Furthermore, the enhanced absorption mechanism revealed that the high-efficiency absorption performance of Si(2)-rGO@Fe₃O₄/PVDF-co-HFP composite was attributed to the interference absorption (quarter-wave matching model) and the synergistic effects between Si(2)-rGO@Fe₃O₄ and PVDF-co-HFP. This work provides a potential strategy for the fabrication of the high-performance EMA materials. Full article

(This article belongs to the Special Issue Synthesis and Applications of Nanoparticles)

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