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16 pages, 3802 KiB

Open AccessArticle

Conversion of Carbon Dioxide into Methanol Using Cu–Zn Nanostructured Materials as Catalysts

by Anna Carrasco García, Javier Moral-Vico, Ahmad Abo Markeb and Antoni Sánchez

Nanomaterials 2022, 12(6), 999; https://doi.org/10.3390/nano12060999 - 18 Mar 2022

Cited by 13 | Viewed by 2982

Nowadays, there is a growing awareness of the great environmental impact caused by the enormous amounts of carbon dioxide emitted. Several alternatives exist to solve this problem, and one of them is the hydrogenation of carbon dioxide into methanol by using nanomaterials as [...] Read more.

Nowadays, there is a growing awareness of the great environmental impact caused by the enormous amounts of carbon dioxide emitted. Several alternatives exist to solve this problem, and one of them is the hydrogenation of carbon dioxide into methanol by using nanomaterials as catalysts. The aim of this alternative is to produce a value-added chemical, such as methanol, which is a cheaply available feedstock. The development of improved materials for this conversion reaction and a deeper study of the existing ones are important for obtaining higher efficiencies in terms of yield, conversion, and methanol selectivity, in addition to allowing milder reaction conditions in terms of pressure and temperature. In this work, the performance of copper, zinc, and zinc oxide nanoparticles in supported and unsupported bimetallic systems is evaluated in order to establish a comparison among the different materials according to their efficiency. For that, a packed bed reactor operating with a continuous gas flow is used. The obtained results indicate that the use of bimetallic systems combined with porous supports, such as zeolite and activated carbon, is beneficial, thus improving the performance of unsupported materials by four times. Full article

(This article belongs to the Special Issue Metallic and Metal Oxide Nanoparticles and Their Applications)

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13 pages, 4193 KiB

Open AccessArticle

A Molecular Communication Platform Based on Body Area Nanonetwork

by Wenxin Pan, Xiaokang Chen, Xiaodong Yang, Nan Zhao, Lingguo Meng and Fiaz Hussain Shah

Nanomaterials 2022, 12(4), 722; https://doi.org/10.3390/nano12040722 - 21 Feb 2022

Cited by 11 | Viewed by 1814

Abstract

With the development of nanotechnology and biotechnology, the nanomachine can be applied to the interior of the human body. In order to achieve the goal of completing complex tasks, measures to connect multiple nanomachines that can complete more simple tasks are taken. This [...] Read more.

With the development of nanotechnology and biotechnology, the nanomachine can be applied to the interior of the human body. In order to achieve the goal of completing complex tasks, measures to connect multiple nanomachines that can complete more simple tasks are taken. This can expand the ability of a single nanomachine to cooperate and share information to complete more complex tasks—namely, the emergence of the Body Area Network (BAN). In response to the requirements of building a BAN, we must first need to solve the communication problem between two nanomachines. Communication networks based on molecular communication (MC), known as “natural body area networks”, are widely used in biomedical fields. With the considerable development of MC theory, it is urgent to set up an experimental platform to verify and guide theoretical modeling. In this paper, a nanomaterial-based MC platform is designed and built to simulate the cardiovascular system. The platform uses the diffusion of nanoscale pigment particles in water solution in silicone tube to achieve communication process and modulates binary sequence information to messenger molecules by on-off keying (OOK). The platform successfully transmits and receives a 17-bit binary sequence to prove its communication possibilities. To assess the platform capabilities, this paper tests the effects of different solution concentrations, pipeline flow rates, and pressure on platform communications. These factors can be used to expand the modulation schemes that the platform can implement. In future work, some nanomaterials that can be used for molecular communication can be applied to the platform to characterize their channel characteristics. Full article

(This article belongs to the Special Issue Metallic and Metal Oxide Nanoparticles and Their Applications)

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12 pages, 1175 KiB

Open AccessArticle

Pharmacokinetics of PEGylated Gold Nanoparticles: In Vitro—In Vivo Correlation

by Tibor Dubaj, Katarina Kozics, Monika Sramkova, Alena Manova, Neus G. Bastús, Oscar H. Moriones, Yvonne Kohl, Maria Dusinska, Elise Runden-Pran, Victor Puntes, Andrew Nelson, Alena Gabelova and Peter Simon

Nanomaterials 2022, 12(3), 511; https://doi.org/10.3390/nano12030511 - 01 Feb 2022

Cited by 19 | Viewed by 2868

Abstract

Data suitable for assembling a physiologically-based pharmacokinetic (PBPK) model for nanoparticles (NPs) remain relatively scarce. Therefore, there is a trend in extrapolating the results of in vitro and in silico studies to in vivo nanoparticle hazard and risk assessment. To evaluate the reliability [...] Read more.

Data suitable for assembling a physiologically-based pharmacokinetic (PBPK) model for nanoparticles (NPs) remain relatively scarce. Therefore, there is a trend in extrapolating the results of in vitro and in silico studies to in vivo nanoparticle hazard and risk assessment. To evaluate the reliability of such approach, a pharmacokinetic study was performed using the same polyethylene glycol-coated gold nanoparticles (PEG-AuNPs) in vitro and in vivo. As in vitro models, human cell lines TH1, A549, Hep G2, and 16HBE were employed. The in vivo PEG-AuNP biodistribution was assessed in rats. The internalization and exclusion of PEG-AuNPs in vitro were modeled as first-order rate processes with the partition coefficient describing the equilibrium distribution. The pharmacokinetic parameters were obtained by fitting the model to the in vitro data and subsequently used for PBPK simulation in vivo. Notable differences were observed in the internalized amount of Au in individual cell lines compared to the corresponding tissues in vivo, with the highest found for renal TH1 cells and kidneys. The main reason for these discrepancies is the absence of natural barriers in the in vitro conditions. Therefore, caution should be exercised when extrapolating in vitro data to predict the in vivo NP burden and response to exposure. Full article

(This article belongs to the Special Issue Metallic and Metal Oxide Nanoparticles and Their Applications)

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18 pages, 2843 KiB

Open AccessArticle

Mono-Doped and Co-Doped Nanostructured Hematite for Improved Photoelectrochemical Water Splitting

by Justine Sageka Nyarige, Alexander T. Paradzah, Tjaart P. J. Krüger and Mmantsae Diale

Nanomaterials 2022, 12(3), 366; https://doi.org/10.3390/nano12030366 - 24 Jan 2022

Cited by 6 | Viewed by 3076

Abstract

In this study, zinc-doped (

α

-Fe

_{2}

O

_{3}

:Zn), silver-doped (

α

-Fe

_{2}

O

_{3}

:Ag) and zinc/silver co-doped hematite (

α

-Fe

_{2}

O

_{3}

:Zn/Ag) nanostructures were synthesized by spray pyrolysis. The synthesized nanostructures were used as photoanodes [...] Read more.

In this study, zinc-doped (

α

-Fe

_{2}

O

_{3}

:Zn), silver-doped (

α

-Fe

_{2}

O

_{3}

:Ag) and zinc/silver co-doped hematite (

α

-Fe

_{2}

O

_{3}

:Zn/Ag) nanostructures were synthesized by spray pyrolysis. The synthesized nanostructures were used as photoanodes in the photoelectrochemical (PEC) cell for water-splitting. A significant improvement in photocurrent density of 0.470 mAcm

^{- 2}

at 1.23 V vs. reversible hydrogen electrode (RHE) was recorded for

α

-Fe

_{2}

O

_{3}

:Zn/Ag. The

α

-Fe

_{2}

O

_{3}

:Ag,

α

-Fe

_{2}

O

_{3}

:Zn and pristine hematite samples produced photocurrent densities of 0.270, 0.160, and 0.033 mAcm

^{- 2}

, respectively. Mott–Schottky analysis showed that

α

-Fe

_{2}

O

_{3}

:Zn/Ag had the highest free carrier density of 8.75 × 10

^{20}

cm

^{- 3}

, while pristine

α

-Fe

_{2}

O

_{3}

,

α

-Fe

_{2}

O

_{3}

:Zn,

α

-Fe

_{2}

O

_{3}

:Ag had carrier densities of 1.57 × 10

^{19}

, 5.63 × 10

^{20}

, and 6.91 × 10

^{20}

cm

^{- 3}

, respectively. Electrochemical impedance spectra revealed a low impedance for

α

-Fe

_{2}

O

_{3}

:Zn/Ag. X-ray diffraction confirmed the rhombohedral corundum structure of hematite. Scanning electron microscopy micrographs, on the other hand, showed uniformly distributed grains with an average size of <30 nm. The films were absorbing in the visible region with an absorption onset ranging from 652 to 590 nm, corresponding to a bandgap range of 1.9 to 2.1 eV. Global analysis of ultrafast transient absorption spectroscopy data revealed four decay lifetimes, with a reduction in the electron-hole recombination rate of the doped samples on a timescale of tens of picoseconds. Full article

(This article belongs to the Special Issue Metallic and Metal Oxide Nanoparticles and Their Applications)

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15 pages, 4088 KiB

Open AccessArticle

Enhanced Photocatalytic Activity and Stability of Bi₂WO₆ – TiO₂-N Nanocomposites in the Oxidation of Volatile Pollutants

by Nikita Kovalevskiy, Svetlana Cherepanova, Evgeny Gerasimov, Mikhail Lyulyukin, Maria Solovyeva, Igor Prosvirin, Denis Kozlov and Dmitry Selishchev

Nanomaterials 2022, 12(3), 359; https://doi.org/10.3390/nano12030359 - 23 Jan 2022

Cited by 16 | Viewed by 2563

Abstract

The development of active and stable photocatalysts for the degradation of volatile organic compounds under visible light is important for efficient light utilization and environmental protection. Titanium dioxide doped with nitrogen is known to have a high activity but it exhibits a relatively [...] Read more.

The development of active and stable photocatalysts for the degradation of volatile organic compounds under visible light is important for efficient light utilization and environmental protection. Titanium dioxide doped with nitrogen is known to have a high activity but it exhibits a relatively low stability due to a gradual degradation of nitrogen species under highly powerful radiation. In this paper, we show that the combination of N-doped TiO₂ with bismuth tungstate prevents its degradation during the photocatalytic process and results in a very stable composite photocatalyst. The synthesis of Bi₂WO₆–TiO₂-N composites is preformed through the hydrothermal treatment of an aqueous medium containing nanocrystalline N-doped TiO₂, as well as bismuth (III) nitrate and sodium tungstate followed by drying in air. The effect of the molar ratio between the components on their characteristics and photocatalytic activity is discussed. In addition to an enhanced stability, the composite photocatalysts with a low content of Bi₂WO₆ also exhibit an enhanced activity that is substantially higher than the activity of individual TiO₂-N and Bi₂WO₆ materials. Thus, the Bi₂WO₆–TiO₂-N composite has the potential as an active and stable photocatalyst for efficient purification of air. Full article

(This article belongs to the Special Issue Metallic and Metal Oxide Nanoparticles and Their Applications)

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15 pages, 1210 KiB

Open AccessArticle

How to Use Localized Surface Plasmon for Monitoring the Adsorption of Thiol Molecules on Gold Nanoparticles?

by Angeline S. Dileseigres, Yoann Prado and Olivier Pluchery

Nanomaterials 2022, 12(2), 292; https://doi.org/10.3390/nano12020292 - 17 Jan 2022

Cited by 9 | Viewed by 2657

Abstract

The functionalization of spherical gold nanoparticles (AuNPs) in solution with thiol molecules is essential for further developing their applications. AuNPs exhibit a clear localized surface plasmon resonance (LSPR) at 520 nm in water for 20 nm size nanoparticles, which is extremely sensitive to [...] Read more.

The functionalization of spherical gold nanoparticles (AuNPs) in solution with thiol molecules is essential for further developing their applications. AuNPs exhibit a clear localized surface plasmon resonance (LSPR) at 520 nm in water for 20 nm size nanoparticles, which is extremely sensitive to the local surface chemistry. In this study, we revisit the use of UV-visible spectroscopy for monitoring the LSPR peak and investigate the progressive reaction of thiol molecules on 22 nm gold nanoparticles. FTIR spectroscopy and TEM are used for confirming the nature of ligands and the nanoparticle diameter. Two thiols are studied: 11-mercaptoundecanoic acid (MUDA) and 16-mercaptohexadecanoic acid (MHDA). Surface saturation is detected after adding 20 nmol of thiols into 1.3 × 10⁻³ nmol of AuNPs, corresponding approximately to 15,000 molecules per AuNPs (which is equivalent to 10.0 molecules per nm²). Saturation corresponds to an LSPR shift of 2.7 nm and 3.9 nm for MUDA and MHDA, respectively. This LSPR shift is analyzed with an easy-to-use analytical model that accurately predicts the wavelength shift. The case of dodecanehtiol (DDT) where the LSPR shift is 15.6 nm is also quickly commented. An insight into the kinetics of the functionalization is obtained by monitoring the reaction for a low thiol concentration, and the reaction appears to be completed in less than one hour. Full article

(This article belongs to the Special Issue Metallic and Metal Oxide Nanoparticles and Their Applications)

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19 pages, 43504 KiB

Open AccessArticle

Magnetically Recoverable Nanoparticulate Catalysts for Cross-Coupling Reactions: The Dendritic Support Influences the Catalytic Performance

by Nina V. Kuchkina, Svetlana A. Sorokina, Alexey V. Bykov, Mikhail G. Sulman, Lyudmila M. Bronstein and Zinaida B. Shifrina

Nanomaterials 2021, 11(12), 3345; https://doi.org/10.3390/nano11123345 - 09 Dec 2021

Cited by 3 | Viewed by 2364

Abstract

Carbon-carbon cross-coupling reactions are among the most important synthetic tools for the preparation of pharmaceuticals and bioactive compounds. However, these reactions are normally carried out using copper, phosphines, and/or amines, which are poisonous for pharmaceuticals. The use of nanocomposite catalysts holds promise for [...] Read more.

Carbon-carbon cross-coupling reactions are among the most important synthetic tools for the preparation of pharmaceuticals and bioactive compounds. However, these reactions are normally carried out using copper, phosphines, and/or amines, which are poisonous for pharmaceuticals. The use of nanocomposite catalysts holds promise for facilitating these reactions and making them more environmentally friendly. In the present work, the PEGylated (PEG stands for poly(ethylene glycol) pyridylphenylene dendrons immobilized on silica loaded with magnetic nanoparticles have been successfully employed for the stabilization of Pd²⁺ complexes and Pd nanoparticles. The catalyst developed showed excellent catalytic activity in copper-free Sonogashira and Heck cross-coupling reactions. The reactions proceeded smoothly in green solvents at low palladium loading, resulting in high yields of cross-coupling products (from 80% to 97%) within short reaction times. The presence of magnetic nanoparticles allows easy magnetic separation for repeated use without a noticeable decrease of catalytic activity due to the strong stabilization of Pd species by rigid and bulky dendritic ligands. The PEG dendron periphery makes the catalyst hydrophilic and better suited for green solvents. The minor drop in activity upon the catalyst reuse is explained by the formation of Pd nanoparticles from the Pd²⁺ species during the catalytic reaction. The magnetic separation and reuse of the nanocomposite catalyst reduces the cost of target products as well as energy and material consumption and diminishes residual contamination by the catalyst. These factors as well as the absence of copper in the catalyst makeup pave the way for future applications of such catalysts in cross-coupling reactions. Full article

(This article belongs to the Special Issue Metallic and Metal Oxide Nanoparticles and Their Applications)

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9 pages, 3226 KiB

Open AccessArticle

Gold Carbide: A Predicted Nanotube Candidate from First Principle

by Xiaohang Lin, Lin Song, Anchen Shao, Minghao Hua and Xuelei Tian

Nanomaterials 2021, 11(12), 3182; https://doi.org/10.3390/nano11123182 - 24 Nov 2021

Viewed by 1498

Abstract

In the present work, density functional theory (DFT) calculations were applied to confirm that the gold carbide previously experimentally synthesized was AuC film. A crucial finding is that these kinds of AuC films are self-folded on the graphite substrate, leading to the formation [...] Read more.

In the present work, density functional theory (DFT) calculations were applied to confirm that the gold carbide previously experimentally synthesized was AuC film. A crucial finding is that these kinds of AuC films are self-folded on the graphite substrate, leading to the formation of a semi-nanotube structure, which significantly diminishes the error between the experimental and simulated lattice constant. The unique characteristic, the spontaneous archlike reconstruction, makes AuC a possible candidate for self-assembled nanotubes. The band structure indicated, in the designed AuC nanotube, a narrow gap semiconductor with a bandgap of 0.14 eV. Both AIMD (at 300 and 450 K) results and phonon spectra showed a rather high stability for the AuC nanotube because a strong chemical bond formed between the Au–5d and C–2p states. The AuC nanotube could become a novel functional material. Full article

(This article belongs to the Special Issue Metallic and Metal Oxide Nanoparticles and Their Applications)

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19 pages, 8397 KiB

Open AccessArticle

Synthesis, Characterization and Photocatalytic Performance of Calcined ZnCr-Layered Double Hydroxides

by Somia Djelloul Bencherif, Juan Jesús Gallardo, Iván Carrillo-Berdugo, Abdellah Bahmani and Javier Navas

Nanomaterials 2021, 11(11), 3051; https://doi.org/10.3390/nano11113051 - 13 Nov 2021

Cited by 6 | Viewed by 2012

Abstract

The development of new materials for performing photocatalytic processes to remove contaminants is an interesting and important research line due to the ever-increasing number of contaminants on our planet. In this sense, we developed a layered double hydroxide material based on Zn and [...] Read more.

The development of new materials for performing photocatalytic processes to remove contaminants is an interesting and important research line due to the ever-increasing number of contaminants on our planet. In this sense, we developed a layered double hydroxide material based on Zn and Cr, which was transformed into the corresponding oxide by heat treatment at 500 °C. Both materials were widely characterized for their elemental composition, and structural, morphological, optical and textural properties using several experimental techniques such as x-ray diffraction, x-ray photoelectron spectroscopy, scanning and transmission electron microscopy, Fourier transform infrared spectroscopy, UV-vis spectroscopy and physisorption techniques. In addition, the photocatalytic activity of both materials was analysed. The calcined one showed interesting photocatalytic activity in photodegradation tests using crystal violet dye. The operational parameters for the photocatalytic process using the calcined material were optimised, considering the pH, the initial concentration of the dye, the catalyst load, and the regeneration of the catalyst. The catalyst showed good photocatalytic activity, reaching a degradation of 100% in the optimised conditions and showing good performance after five photodegradation cycles. Full article

(This article belongs to the Special Issue Metallic and Metal Oxide Nanoparticles and Their Applications)

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13 pages, 22658 KiB

Open AccessArticle

Peptide Specific Nanoplastic Detection Based on Sandwich Typed Localized Surface Plasmon Resonance

by Seungju Oh, Hyeyeon Hur, Yoonjae Kim, Seongcheol Shin, Hyunjeong Woo, Jonghoon Choi and Hyun Ho Lee

Nanomaterials 2021, 11(11), 2887; https://doi.org/10.3390/nano11112887 - 28 Oct 2021

Cited by 8 | Viewed by 3081

Abstract

Recently, various waste microplastics sensors have been introduced in response to environmental and biological hazards posed by waste microplastics. In particular, the detrimental effects of nano-sized plastics or nanoplastics have been reported to be severe. Moreover, there have been many difficulties for sensing [...] Read more.

Recently, various waste microplastics sensors have been introduced in response to environmental and biological hazards posed by waste microplastics. In particular, the detrimental effects of nano-sized plastics or nanoplastics have been reported to be severe. Moreover, there have been many difficulties for sensing microplastics due to the limited methodologies for selectively recognizing nanoplastics. In this study, a customized gold nanoparticles (Au NPs) based localized surface plasmon resonance (LSPR) system having bio-mimicked peptide probes toward the nanoplastics was demonstrated. The specific determination through the oligo-peptide recognition was accomplished by chemical conjugation both on the LSPR chip’s 40~50 nm Au NPs and sandwiched 5 nm Au NPs, respectively. The peptide probe could selectively bind to polystyrene (PS) nanoplastics in the forms of fragmented debris by cryo-grinding. A simple UV-Vis spectrophotometer was used to identify the LSPR sensing by primarily measuring the absorbance change and shift of absorption peak. The sandwich-binding could increase the LSPR detection sensitivity up to 60% due to consecutive plasmonic effects. In addition, microwave-boiled DI water inside of a styrofoam container was tested for putative PS nanoplastics resource as a real accessible sample. The LSPR system could be a novel protocol overcoming the limitations from conventional nanoplastic detection. Full article

(This article belongs to the Special Issue Metallic and Metal Oxide Nanoparticles and Their Applications)

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24 pages, 18839 KiB

Open AccessArticle

Bimetallic M–Cu (M = Ag, Au, Ni) Nanoparticles Supported on γAl₂O₃-CeO₂ Synthesized by a Redox Method Applied in Wet Oxidation of Phenol in Aqueous Solution and Petroleum Refinery Wastewater

by Zenaida Guerra-Que, Jorge Cortez-Elizalde, Hermicenda Pérez-Vidal, Juan C. Arévalo-Pérez, Adib A. Silahua-Pavón, Gerardo E. Córdova-Pérez, Ignacio Cuauhtémoc-López, Héctor Martínez-García, Anabel González-Díaz and José Gilberto Torres-Torres

Nanomaterials 2021, 11(10), 2570; https://doi.org/10.3390/nano11102570 - 30 Sep 2021

Cited by 3 | Viewed by 2171

Abstract

Three bimetallic catalysts of the type M–Cu with M = Ag, Au and Ni supports were successfully prepared by a two-step synthesized method using Cu/Al₂O₃-CeO₂ as the base monometallic catalyst. The nanocatalysts were characterized using X-ray diffraction (XRD), [...] Read more.

Three bimetallic catalysts of the type M–Cu with M = Ag, Au and Ni supports were successfully prepared by a two-step synthesized method using Cu/Al₂O₃-CeO₂ as the base monometallic catalyst. The nanocatalysts were characterized using X-ray diffraction (XRD), temperature-programmed reduction of H₂ (H₂-TPR), N₂ adsorption-desorption, scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM) and ultraviolet–visible spectroscopy with diffuse reflectance (DR-UV-Vis) techniques. This synthesized methodology allowed a close interaction between two metals on the support surface; therefore, it could have synthesized an efficient transition–noble mixture bimetallic nanostructure. Alloy formation through bimetallic nanoparticles (BNPs) of AgCuAlCe and AuCuAlCe was demonstrated by DR–UV–Vis, EDS, TEM and H₂-TPR. Furthermore, in the case of AgCuAlCe and AuCuAlCe, improvements were observed in their reducibility, in contrast to NiCuAlCe. The addition of a noble metal over the monometallic copper-based catalyst drastically improved the phenol mineralization. The higher activity and selectivity to CO₂ of the bimetallic gold–copper- and silver–copper-supported catalysts can be attributed to the alloy compound formation and the synergetic effect of the M–Cu interaction. Petroleum Refinery Wastewater (PRW) had a complex composition that affected the applied single CWAO treatment, rendering it inefficient. Full article

(This article belongs to the Special Issue Metallic and Metal Oxide Nanoparticles and Their Applications)

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18 pages, 11978 KiB

Open AccessArticle

Biofilm-Resistant Nanocoatings Based on ZnO Nanoparticles and Linalool

by Vera Alexandra Spirescu, Raluca Șuhan, Adelina-Gabriela Niculescu, Valentina Grumezescu, Irina Negut, Alina Maria Holban, Ovidiu-Cristian Oprea, Alexandra Cătălina Bîrcă, Bogdan Ștefan Vasile, Alexandru Mihai Grumezescu, Ludovic Everard Bejenaru, George Dan Mogoşanu, Cornelia Bejenaru, Paul Cătălin Balaure, Ecaterina Andronescu and Laurenţiu Mogoantă

Nanomaterials 2021, 11(10), 2564; https://doi.org/10.3390/nano11102564 - 29 Sep 2021

Cited by 16 | Viewed by 2620

Abstract

Biofilms represent an increasing challenge in the medical practice worldwide, imposing a serious threat to public health. As bacterial strains have developed antibiotic resistance, researcher’s attention has been extensively focused on developing more efficient antimicrobial strategies. In this context, the present study reports [...] Read more.

Biofilms represent an increasing challenge in the medical practice worldwide, imposing a serious threat to public health. As bacterial strains have developed antibiotic resistance, researcher’s attention has been extensively focused on developing more efficient antimicrobial strategies. In this context, the present study reports the synthesis, physicochemical characterization, ex vivo biodistribution, and in vitro evaluation of the capacity of nanostructured surfaces based on zinc oxide (ZnO) and biologically active molecules to modulate clinically relevant microbial biofilms. ZnO nanoparticles (NPs) were synthesized through a co-precipitation method without thermal treatment. The matrix-assisted pulsed laser evaporation (MAPLE) was applied for preparing nanostructured coatings based on ZnO NPs surface modified with linalool that were further characterized by X-ray diffraction (XRD), thermogravimetric analysis with differential scanning calorimetry (TGA-DSC), scanning electron microscopy (SEM), transmission electron microscopy with selected area electron diffraction (TEM-SAED), Fourier-transform infrared spectroscopy (FT-IR), and infrared microscopy (IRM). Histological analyses carried out at 7 days and 14 days after the intraperitoneal administration of linalool modified ZnO NPs revealed the absence of the latter from the brain, kidney, liver, lung, myocardium, and pancreas. Through in vitro assays on prokaryotic cells, it was proven that ZnO coatings hinder microbial biofilm formation of both Gram-positive and Gram-negative bacteria strains. Full article

(This article belongs to the Special Issue Metallic and Metal Oxide Nanoparticles and Their Applications)

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11 pages, 1631 KiB

Open AccessArticle

Giant Second Harmonic Generation Enhancement by Ag Nanoparticles Compactly Distributed on Hexagonal Arrangements

by Alejandro Gómez-Tornero, Luisa E. Bausá and Mariola O. Ramírez

Nanomaterials 2021, 11(9), 2394; https://doi.org/10.3390/nano11092394 - 14 Sep 2021

Viewed by 2049

Abstract

The association of plasmonic nanostructures with nonlinear dielectric systems has been shown to provide useful platforms for boosting frequency conversion processes at metal-dielectric interfaces. Here, we report on an efficient route for engineering light–matter interaction processes in hybrid plasmonic-χ⁽²⁾ dielectric systems to [...] Read more.

The association of plasmonic nanostructures with nonlinear dielectric systems has been shown to provide useful platforms for boosting frequency conversion processes at metal-dielectric interfaces. Here, we report on an efficient route for engineering light–matter interaction processes in hybrid plasmonic-χ⁽²⁾ dielectric systems to enhance second harmonic generation (SHG) processes confined in small spatial regions. By means of ferroelectric lithography, we have fabricated scalable micrometric arrangements of interacting silver nanoparticles compactly distributed on hexagonal regions. The fabricated polygonal microstructures support both localized and extended plasmonic modes, providing large spatial regions of field enhancement at the optical frequencies involved in the SHG process. We experimentally demonstrate that the resonant excitation of the plasmonic modes supported by the Ag nanoparticle-filled hexagons in the near infrared region produces an extraordinary 10⁴-fold enhancement of the blue second harmonic intensity generated in the surface of a LiNbO₃ crystal. The results open new perspectives for the design of efficient hybrid plasmonic frequency converters in miniaturized devices. Full article

(This article belongs to the Special Issue Metallic and Metal Oxide Nanoparticles and Their Applications)

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12 pages, 1191 KiB

Open AccessEditor’s ChoiceArticle

Solid State Photoreduction of Silver on Mesoporous Silica to Enhance Antifungal Activity

by Giulia Quaglia, Valeria Ambrogi, Donatella Pietrella, Morena Nocchetti and Loredana Latterini

Nanomaterials 2021, 11(9), 2340; https://doi.org/10.3390/nano11092340 - 09 Sep 2021

Cited by 6 | Viewed by 2077

Abstract

A solid-state Ultraviolet-photoreduction process of silver cations to produce Ag⁰ nanostructures on a mesoporous silica is presented as an innovative method for the preparation of efficient environmental anti-fouling agents. Mesoporous silica powder, contacted with AgNO₃, is irradiated at 366 nm, [...] Read more.

A solid-state Ultraviolet-photoreduction process of silver cations to produce Ag⁰ nanostructures on a mesoporous silica is presented as an innovative method for the preparation of efficient environmental anti-fouling agents. Mesoporous silica powder, contacted with AgNO₃, is irradiated at 366 nm, where silica surface defects absorb. The detailed characterization of the materials enables us to document the silica assisted photo-reduction. The appearance of a Visible (Vis) band centered at 470 nm in the extinction spectra, due to the surface plasmon resonance of Ag⁰ nanostructures, and the morphology changes observed in transmission electron microscopy (TEM) images, associated with the increase of Ag/O ratio in energy dispersive X-ray (EDX) analysis, indicate the photo-induced formation of Ag⁰. The data demonstrate that the photo-induced reduction of silver cation occurs in the solid state and takes place through the activation of silica defects. The activation of the materials after UV-processing is then tested, evaluating their antimicrobial activity using an environmental filamentous fungus, Aspergillus niger. The treatment doubled inhibitory capacity in terms of minimal inhibitory concentration (MIC) and biofilm growth. The antimicrobial properties of silver–silica nanocomposites are investigated when dispersed in a commercial sealant; the nanocomposites show excellent dispersion in the silicon and improve its anti-fouling capacity. Full article

(This article belongs to the Special Issue Metallic and Metal Oxide Nanoparticles and Their Applications)

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14 pages, 6867 KiB

Open AccessArticle

Green Synthesis of Cu Nanoparticles in Modulating the Reactivity of Amine-Functionalized Composite Materials towards Cross-Coupling Reactions

by Surjyakanta Rana, G. Bishwa Bidita Varadwaj and Sreekanth B. Jonnalagadda

Nanomaterials 2021, 11(9), 2260; https://doi.org/10.3390/nano11092260 - 31 Aug 2021

Cited by 1 | Viewed by 2079

Abstract

Control over both dispersion and the particle size distribution of supported metal particles is of paramount importance for the catalytic activity of composite materials. We describe the synthesis of materials with Cu nanoparticles well-dispersed on different amine-functionalized supports, using the extract of Wallich [...] Read more.

Control over both dispersion and the particle size distribution of supported metal particles is of paramount importance for the catalytic activity of composite materials. We describe the synthesis of materials with Cu nanoparticles well-dispersed on different amine-functionalized supports, using the extract of Wallich Spurge as a green, reducing agent. Graphene oxide (GO), mesoporous silica (MCM-41), mesoporous zirconia, and reduced graphene oxide-mesoporous silica (RGO-MCM-41) were explored as supports. Cu nanoparticles were better stabilized on RGO-MCM-41 compared to other supports. The novel composite materials were characterized by X-ray diffraction (XRD), Raman spectra, Scanning electron microscope (SEM), Transmission electron microscopy analysis and HR-TEM. SEM and EDX techniques. High angle XRD confirmed the conversion of graphene oxide to reduced graphene oxide (RGO) with plant extract as a reducing agent. Both XRD and TEM techniques confirmed the Cu nanoparticle formation. The catalytic activity of all the prepared materials for the Ullmann coupling reactions of carbon-, oxygen-, and nitrogen-containing nucleophiles with iodobenzene was evaluated. From the results, 5 wt% Cu on amine-functionalized reduced graphene oxide/mesoporous silica nanocomposite (5 wt%Cu(0)-AAPTMS@RGO-MCM-41) exhibited excellent efficiency with 97% yield of the C-C coupling product in water at 80 °C in 5 h. The activity remained unaltered almost up to the fourth cycle. The Cu nanoparticles stabilized by organic amine group on RGO hybrid facilitated sustained activity. Full article

(This article belongs to the Special Issue Metallic and Metal Oxide Nanoparticles and Their Applications)

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12 pages, 2360 KiB

Open AccessArticle

Carbon Quantum Dots Conjugated Rhodium Nanoparticles as Hybrid Multimodal Contrast Agents

by Giovanni M. Saladino, Nuzhet I. Kilic, Bertha Brodin, Bejan Hamawandi, Idris Yazgan, Hans M. Hertz and Muhammet S. Toprak

Nanomaterials 2021, 11(9), 2165; https://doi.org/10.3390/nano11092165 - 24 Aug 2021

Cited by 11 | Viewed by 3770

Abstract

Nanoparticle (NP)-based contrast agents enabling different imaging modalities are sought for non-invasive bio-diagnostics. A hybrid material, combining optical and X-ray fluorescence is presented as a bioimaging contrast agent. Core NPs based on metallic rhodium (Rh) have been demonstrated to be potential X-ray Fluorescence [...] Read more.

Nanoparticle (NP)-based contrast agents enabling different imaging modalities are sought for non-invasive bio-diagnostics. A hybrid material, combining optical and X-ray fluorescence is presented as a bioimaging contrast agent. Core NPs based on metallic rhodium (Rh) have been demonstrated to be potential X-ray Fluorescence Computed Tomography (XFCT) contrast agents. Microwave-assisted hydrothermal method is used for NP synthesis, yielding large-scale NPs within a significantly short reaction time. Rh NP synthesis is performed by using a custom designed sugar ligand (LODAN), constituting a strong reducing agent in aqueous solution, which yields NPs with primary amines as surface functional groups. The amino groups on Rh NPs are used to directly conjugate excitation-independent nitrogen-doped carbon quantum dots (CQDs), which are synthesized through citrate pyrolysis in ammonia solution. CQDs provided the Rh NPs with optical fluorescence properties and improved their biocompatibility, as demonstrated in vitro by Real-Time Cell Analysis (RTCA) on a macrophage cell line (RAW 264.7). The multimodal characteristics of the hybrid NPs are confirmed with confocal microscopy, and X-ray Fluorescence (XRF) phantom experiments. Full article

(This article belongs to the Special Issue Metallic and Metal Oxide Nanoparticles and Their Applications)

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18 pages, 4909 KiB

Open AccessArticle

Synthesis of Ag Nanoparticles-Decorated CNTs via Laser Ablation Method for the Enhancement the Photocatalytic Removal of Naphthalene from Water

by Fowzia S. Alamro, Ayman M. Mostafa, Khulood A. Abu Al-Ola, Hoda A. Ahmed and Arafat Toghan

Nanomaterials 2021, 11(8), 2142; https://doi.org/10.3390/nano11082142 - 22 Aug 2021

Cited by 47 | Viewed by 2882

Abstract

Silver nanoparticles (Ag NPs) were decorated with different amounts on the exterior walls of carbon nanotubes (CNTs) by a laser ablation assisted method, especially in liquid media to be applied as a good adsorption material against naphthalene. The laser ablation time was controlled [...] Read more.

Silver nanoparticles (Ag NPs) were decorated with different amounts on the exterior walls of carbon nanotubes (CNTs) by a laser ablation assisted method, especially in liquid media to be applied as a good adsorption material against naphthalene. The laser ablation time was controlled the amount of decoration Ag NPs on CNTs. The prepared nanocomposite was analyzed via different analytical techniques. Ag NPs with a small size distribution of 29 nm are uniformly decorated with spherical shape on CNTs walls. The disorder degree of tubular structure and shifting of the vibrational characteristic peaks increase with the increase in the decoration of Ag NPs. After that, the prepared samples were investigated for the removal of naphthalene. These studies of loading Ag NPs with different amounts on the surface of CNTs act as a promising material for water treatment. Full article

(This article belongs to the Special Issue Metallic and Metal Oxide Nanoparticles and Their Applications)

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14 pages, 1384 KiB

Open AccessArticle

AgNPs Argovit™ Modulates Cyclophosphamide-Induced Genotoxicity on Peripheral Blood Erythrocytes In Vivo

by Idalia Yazmin Castañeda-Yslas, Olivia Torres-Bugarín, Juan Carlos García-Ramos, Yanis Toledano-Magaña, Patricia Radilla-Chávez, Nina Bogdanchikova, Alexey Pestryakov, Balam Ruiz-Ruiz and María Evarista Arellano-García

Nanomaterials 2021, 11(8), 2096; https://doi.org/10.3390/nano11082096 - 18 Aug 2021

Cited by 1 | Viewed by 2399

Abstract

Silver nanoparticles (AgNPs) have been studied worldwide for their potential biomedical applications. Specifically, they are proposed as a novel alternative for cancer treatment. However, the determination of their cytotoxic and genotoxic effects continues to limit their application. The commercially available silver nanoparticle Argovit™ [...] Read more.

Silver nanoparticles (AgNPs) have been studied worldwide for their potential biomedical applications. Specifically, they are proposed as a novel alternative for cancer treatment. However, the determination of their cytotoxic and genotoxic effects continues to limit their application. The commercially available silver nanoparticle Argovit™ has shown antineoplastic, antiviral, antibacterial, and tissue regenerative properties, activities triggered by its capacity to promote the overproduction of reactive oxygen species (ROS). Therefore, in this work, we evaluated the genotoxic and cytotoxic potential of the Argovit™ formulation (average size: 35 nm) on BALB/c mice using the micronucleus in a peripheral blood erythrocytes model. Besides, we evaluated the capability of AgNPs to modulate the genotoxic effect induced by cyclophosphamide (CP) after the administration of the oncologic agent. To achieve this, 5–6-week-old male mice with a mean weight of 20.11 ± 2.38 g were treated with water as negative control (Group 1), an single intraperitoneal dose of CP (50 mg/kg of body weight, Group 2), a daily oral dose of AgNPs (6 mg/kg of weight, Group 3) for three consecutive days, or a combination of these treatment schemes: one day of CP doses (50 mg/kg of body weight) followed by three doses of AgNPs (one dose per day, Group 4) and three alternate doses of CP and AgNPs (six days of exposure, Group 5). Blood samples were taken just before the first administration (0 h) and every 24 h for seven days. Our results show that Argovit™ AgNPs induced no significant cytotoxic or acute genotoxic damage. The observed cumulative genotoxic damage in this model could be caused by the accumulation of AgNPs due to administered consecutive doses. Furthermore, the administration of AgNPs after 24 h of CP seems to have a protective effect on bone marrow and reduces by up to 50% the acute genotoxic damage induced by CP. However, this protection is not enough to counteract several doses of CP. To our knowledge, this is the first time that the exceptional chemoprotective capacity produced by a non-cytotoxic silver nanoparticle formulation against CP genotoxic damage has been reported. These findings raise the possibility of using AgNPs as an adjuvant agent with current treatments, reducing adverse effects. Full article

(This article belongs to the Special Issue Metallic and Metal Oxide Nanoparticles and Their Applications)

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19 pages, 25927 KiB

Open AccessArticle

Co₂P₂O₇ Microplate/Bacterial Cellulose–Derived Carbon Nanofiber Composites with Enhanced Electrochemical Performance

by Likkhasit Wannasen, Wiyada Mongkolthanaruk, Ekaphan Swatsitang, Prasert Pavasant and Supree Pinitsoontorn

Nanomaterials 2021, 11(8), 2015; https://doi.org/10.3390/nano11082015 - 06 Aug 2021

Cited by 8 | Viewed by 1966

Abstract

Nanocrystalline Co₂P₂O₇ and carbon nanofiber (Co₂P₂O₇/CNFs) composites with enhanced electrochemical performance were obtained by calcination after a hydrothermal process with NH₄CoPO₄∙H₂O/bacterial cellulose precursors under an argon [...] Read more.

Nanocrystalline Co₂P₂O₇ and carbon nanofiber (Co₂P₂O₇/CNFs) composites with enhanced electrochemical performance were obtained by calcination after a hydrothermal process with NH₄CoPO₄∙H₂O/bacterial cellulose precursors under an argon atmosphere. SEM images showed that the CNFs were highly dispersed on the surfaces of Co₂P₂O₇ microplates. The diagonal size of the Co₂P₂O₇ plates ranged from 5 to 25 µm with thicknesses on a nanometer scale. Notably, with the optimal calcining temperature, the Co₂P₂O₇/CNFs@600 material has higher specific micropore and mesopore surface areas than other samples, and a maximal specific capacitance of 209.9 F g⁻¹, at a current density of 0.5 A g⁻¹. Interestingly, CNF composite electrodes can enhance electrochemical properties, and contribute to better electrical conductivity and electron transfer. EIS measurements showed that the charge–transfer resistance (R_ct) of the CNF composite electrodes decreased with increasing calcination temperature. Furthermore, the Co₂P₂O₇/CNF electrodes exhibited higher energy and power densities than Co₂P₂O₇ electrodes. Full article

(This article belongs to the Special Issue Metallic and Metal Oxide Nanoparticles and Their Applications)

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23 pages, 3151 KiB

Open AccessArticle

The Biolog EcoPlate™ Technique for Assessing the Effect of Metal Oxide Nanoparticles on Freshwater Microbial Communities

by Imre Németh, Szabina Molnár, Emese Vaszita and Mónika Molnár

Nanomaterials 2021, 11(7), 1777; https://doi.org/10.3390/nano11071777 - 08 Jul 2021

Cited by 17 | Viewed by 5544

Abstract

The application of Biolog EcoPlate™ for community-level physiological profiling of soils is well documented; however, the functional diversity of aquatic bacterial communities has been hardly studied. The objective of this study was to investigate the applicability of the Biolog EcoPlate™ technique and evaluate [...] Read more.

The application of Biolog EcoPlate™ for community-level physiological profiling of soils is well documented; however, the functional diversity of aquatic bacterial communities has been hardly studied. The objective of this study was to investigate the applicability of the Biolog EcoPlate™ technique and evaluate comparatively the applied endpoints, for the characterisation of the effects of metal oxide nanoparticles (MONPs) on freshwater microbial communities. Microcosm experiments were run to assess the effect of nano ZnO and nano TiO₂ in freshwater at 0.8–100 mg/L concentration range. The average well colour development, substrate average well colour development, substrate richness, Shannon index and evenness, Simpson index, McIntosh index and Gini coefficient were determined to quantify the metabolic capabilities and functional diversity. Comprehensive analysis of the experimental data demonstrated that short-term exposure to TiO₂ and ZnO NPs affected the metabolic activity at different extent and through different mechanisms of action. TiO₂ NPs displayed lower impact on the metabolic profile showing up to 30% inhibition. However, the inhibitory effect of ZnO NPs reached 99% with clearly concentration-dependent responses. This study demonstrated that the McIntosh and Gini coefficients were well applicable and sensitive diversity indices. The parallel use of general metabolic capabilities and functional diversity indices may improve the output information of the ecological studies on microbial communities. Full article

(This article belongs to the Special Issue Metallic and Metal Oxide Nanoparticles and Their Applications)

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16 pages, 4418 KiB

Open AccessArticle

Effects of Zinc Oxide Nanoparticles on Physiological and Anatomical Indices in Spring Barley Tissues

by Vishnu D. Rajput, Tatiana Minkina, Aleksei Fedorenko, Natalia Chernikova, Tara Hassan, Saglara Mandzhieva, Svetlana Sushkova, Vladimir Lysenko, Mikhail A. Soldatov and Marina Burachevskaya

Nanomaterials 2021, 11(7), 1722; https://doi.org/10.3390/nano11071722 - 30 Jun 2021

Cited by 59 | Viewed by 3696

Abstract

The aim of the present work was to investigate the toxic effects of zinc oxide nanoparticles (ZnO NPs, particle size < 50 nm) on the physiological and anatomical indices of spring barley (Hordeum sativum L.). The results show that ZnO NPs inhibited [...] Read more.

The aim of the present work was to investigate the toxic effects of zinc oxide nanoparticles (ZnO NPs, particle size < 50 nm) on the physiological and anatomical indices of spring barley (Hordeum sativum L.). The results show that ZnO NPs inhibited H. sativum growth by affecting the chlorophyll fluorescence emissions and causing deformations of the stomatal and trichome morphology, alterations to the cellular organizations, including irregularities of the chloroplasts, and disruptions to the grana and thylakoid organizations. There was a lower number of chloroplasts per cell observed in the H. sativum leaf cells treated with ZnO NPs as compared to the non-treated plants. Cytomorphometric quantification revealed that ZnO NPs decreased the size of the chloroplast by 1.5 and 4 times in 300 and 2000 mg/L ZnO NP-treated plants, respectively. The elemental analysis showed higher Zn accumulation in the treated leaf tissues (3.8 and 10.18-fold with 300 and 2000 mg/L ZnO NPs, respectively) than the untreated. High contents of Zn were observed in several spots in ZnO NP-treated leaf tissues using X-ray fluorescence. Deviations in the anatomical indices were significantly correlated with physiological observations. The accumulation of Zn content in plant tissues that originated from ZnO NPs was shown to cause damage to the structural organization of the photosynthetic apparatus and reduced the photosynthetic activities. Full article

(This article belongs to the Special Issue Metallic and Metal Oxide Nanoparticles and Their Applications)

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13 pages, 26505 KiB

Open AccessArticle

Theragnostic Glycol Chitosan-Conjugated Gold Nanoparticles for Photoacoustic Imaging of Regional Lymph Nodes and Delivering Tumor Antigen to Lymph Nodes

by In-Cheol Sun, SeongHoon Jo, Diego Dumani, Wan Su Yun, Hong Yeol Yoon, Dong-Kwon Lim, Cheol-Hee Ahn, Stanislav Emelianov and Kwangmeyung Kim

Nanomaterials 2021, 11(7), 1700; https://doi.org/10.3390/nano11071700 - 28 Jun 2021

Cited by 13 | Viewed by 5837

Abstract

Lymph node mapping is important in cancer immunotherapy because the morphology of lymph nodes is one of the crucial evaluation criteria of immune responses. We developed new theragnostic glycol-chitosan-coated gold nanoparticles (GC-AuNPs), which highlighted lymph nodes in ultrasound-guided photoacoustic (US/PA) imaging. Moreover, the [...] Read more.

Lymph node mapping is important in cancer immunotherapy because the morphology of lymph nodes is one of the crucial evaluation criteria of immune responses. We developed new theragnostic glycol-chitosan-coated gold nanoparticles (GC-AuNPs), which highlighted lymph nodes in ultrasound-guided photoacoustic (US/PA) imaging. Moreover, the ovalbumin epitope was conjugated GC-AuNPs (OVA-GC-AuNPs) for delivering tumor antigen to lymph node resident macrophage. In vitro studies proved the vigorous endocytosis activity of J774A.1 macrophage and consequent strong photoacoustic signals from them. The macrophages also presented a tumor antigen when OVA-GC-AuNPs were used for cellular uptake. After the lingual injection of GC-AuNPs into healthy mice, cervical lymph nodes were visible in a US/PA imaging system with high contrast. Three-dimensional analysis of lymph nodes revealed that the accumulation of GC-AuNPs in the lymph node increased as the post-injection time passed. Histological analysis showed GC-AuNPs or OVA-GC-AuNPs located in subcapsular and medullar sinuses where macrophages are abundant. Our new theragnostic GC-AuNPs present a superior performance in US/PA imaging of lymph nodes without targeting moieties or complex surface modification. Simultaneously, GC-AuNPs were able to deliver tumor antigens to cause macrophages to present the OVA epitope at targeted lymph nodes, which would be valuable for cancer immunotherapy. Full article

(This article belongs to the Special Issue Metallic and Metal Oxide Nanoparticles and Their Applications)

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15 pages, 5795 KiB

Open AccessArticle

The Multifunctionally Graded System for a Controlled Size Effect on Iron Oxide–Gold Based Core-Shell Nanoparticles

by Bo-Wei Du, Chih-Yuan Chu, Ching-Chang Lin and Fu-Hsiang Ko

Nanomaterials 2021, 11(7), 1695; https://doi.org/10.3390/nano11071695 - 28 Jun 2021

Cited by 5 | Viewed by 1892

Abstract

We report that Fe₃O₄@Au core-shell nanoparticles (NPs) serve as a multifunctional molecule delivery platform. This platform is also suitable for sensing the doxorubicin (DOX) through DNA hybridization, and the amount of carried DOX molecules was determined by size-dependent Fe [...] Read more.

We report that Fe₃O₄@Au core-shell nanoparticles (NPs) serve as a multifunctional molecule delivery platform. This platform is also suitable for sensing the doxorubicin (DOX) through DNA hybridization, and the amount of carried DOX molecules was determined by size-dependent Fe₃O₄@Au NPs. The limits of detection (LODs) for DOX was found to be 1.839 nM. In our approach, an Au nano-shell coating was coupled with a specially designed DNA sequence using thiol bonding. By means of a high-frequency magnetic field (HFMF), a high release percentage of such a molecule could be efficiently achieved in a relatively short period of time. Furthermore, the thickness increase of the Au nano-shell affords Fe₃O₄@Au NPs with a larger surface area and a smaller temperature increment due to shielding effects from magnetic field. The change of magnetic property may enable the developed Fe₃O₄@Au-dsDNA/DOX NPs to be used as future nanocarrier material. More importantly, the core-shell NP structures were demonstrated to act as a controllable and efficient factor for molecule delivery. Full article

(This article belongs to the Special Issue Metallic and Metal Oxide Nanoparticles and Their Applications)

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17 pages, 4171 KiB

Open AccessArticle

Biosynthesis Microwave-Assisted of Zinc Oxide Nanoparticles with Ziziphus jujuba Leaves Extract: Characterization and Photocatalytic Application

by Maymounah N. Alharthi, Iqbal Ismail, Stefano Bellucci, Nezar H. Khdary and Mohamed Abdel Salam

Nanomaterials 2021, 11(7), 1682; https://doi.org/10.3390/nano11071682 - 26 Jun 2021

Cited by 27 | Viewed by 3025

Abstract

The present work is intended to biosynthesize zinc oxide nanoparticles (ZnO NPs) via facile and modern route using aqueous Ziziphus jujuba leaves extract assisted by microwave and explore their photocatalytic degradation of methyl orange anionic dye and methylene blue cationic dye under solar [...] Read more.

The present work is intended to biosynthesize zinc oxide nanoparticles (ZnO NPs) via facile and modern route using aqueous Ziziphus jujuba leaves extract assisted by microwave and explore their photocatalytic degradation of methyl orange anionic dye and methylene blue cationic dye under solar irradiation. The biosynthesized microwave assisted ZnO NPs were characterized and the results showed that ZnO NPs contain hexagonal wurtzite and characterized with a well-defined spherical-like shape with an outstanding band gap (2.70 eV), average particle size of 25 nm and specific surface area of 11.4 m²/g. The photocatalytic degradation of the MO and MB dyes by biosynthesized ZnO NPs under solar irradiation was studied and the results revealed the selective nature of the ZnO NPs for the adsorption and further photocatalytic degradation of the MO dye compared to the MB dye. In addition, the photocatalytic degradation of MO and MB dyes by the ZnO NPs under solar radiation was fitted by the first-order kinetics. Moreover, the photodegradation mechanism proposed that superoxide ions and hydroxyl radicals are the main reactive species. Full article

(This article belongs to the Special Issue Metallic and Metal Oxide Nanoparticles and Their Applications)

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12 pages, 4280 KiB

Open AccessArticle

Effect of the Nanostructured Zn/Cu Electrocatalyst Morphology on the Electrochemical Reduction of CO₂ to Value-Added Chemicals

by Piriya Pinthong, Phongsathon Klongklaew, Piyasan Praserthdam and Joongjai Panpranot

Nanomaterials 2021, 11(7), 1671; https://doi.org/10.3390/nano11071671 - 25 Jun 2021

Cited by 7 | Viewed by 2733

Abstract

Zn/Cu electrocatalysts were synthesized by the electrodeposition method with various bath compositions and deposition times. X-ray diffraction results confirmed the presence of (101) and (002) lattice structures for all the deposited Zn nanoparticles. However, a bulky (hexagonal) structure with particle size in the [...] Read more.

Zn/Cu electrocatalysts were synthesized by the electrodeposition method with various bath compositions and deposition times. X-ray diffraction results confirmed the presence of (101) and (002) lattice structures for all the deposited Zn nanoparticles. However, a bulky (hexagonal) structure with particle size in the range of 1–10 μm was obtained from a high-Zn-concentration bath, whereas a fern-like dendritic structure was produced using a low Zn concentration. A larger particle size of Zn dendrites could also be obtained when Cu²⁺ ions were added to the high-Zn-concentration bath. The catalysts were tested in the electrochemical reduction of CO₂ (CO₂RR) using an H-cell type reactor under ambient conditions. Despite the different sizes/shapes, the CO₂RR products obtained on the nanostructured Zn catalysts depended largely on their morphologies. All the dendritic structures led to high CO production rates, while the bulky Zn structure produced formate as the major product, with limited amounts of gaseous CO and H₂. The highest CO/H₂ production rate ratio of 4.7 and a stable CO production rate of 3.55 μmol/min were obtained over the dendritic structure of the Zn/Cu–Na200 catalyst at −1.6 V vs. Ag/AgCl during 4 h CO₂RR. The dissolution and re-deposition of Zn nanoparticles occurred but did not affect the activity and selectivity in the CO₂RR of the electrodeposited Zn catalysts. The present results show the possibilities to enhance the activity and to control the selectivity of CO₂RR products on nanostructured Zn catalysts. Full article

(This article belongs to the Special Issue Metallic and Metal Oxide Nanoparticles and Their Applications)

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14 pages, 1723 KiB

Open AccessArticle

Nanoceria Prevents Glucose-Induced Protein Glycation in Eye Lens Cells

by Belal I. Hanafy, Gareth W. V. Cave, Yvonne Barnett and Barbara K. Pierscionek

Nanomaterials 2021, 11(6), 1473; https://doi.org/10.3390/nano11061473 - 01 Jun 2021

Cited by 8 | Viewed by 3205

Abstract

Cerium oxide nanoparticles (nanoceria) are generally known for their recyclable antioxidative properties making them an appealing biomaterial for protecting against physiological and pathological age-related changes that are caused by reactive oxygen species (ROS). Cataract is one such pathology that has been associated with [...] Read more.

Cerium oxide nanoparticles (nanoceria) are generally known for their recyclable antioxidative properties making them an appealing biomaterial for protecting against physiological and pathological age-related changes that are caused by reactive oxygen species (ROS). Cataract is one such pathology that has been associated with oxidation and glycation of the lens proteins (crystallins) leading to aggregation and opacification. A novel coated nanoceria formulation has been previously shown to enter the human lens epithelial cells (HLECs) and protect them from oxidative stress induced by hydrogen peroxide (H₂O₂). In this work, the mechanism of nanoceria uptake in HLECs is studied and multiple anti-cataractogenic properties are assessed in vitro. Our results show that the nanoceria provide multiple beneficial actions to delay cataract progression by (1) acting as a catalase mimetic in cells with inhibited catalase, (2) improving reduced to oxidised glutathione ratio (GSH/GSSG) in HLECs, and (3) inhibiting the non-enzymatic glucose-induced glycation of the chaperone lens protein α-crystallin. Given the multifactorial nature of cataract progression, the varied actions of nanoceria render them promising candidates for potential non-surgical therapeutic treatment. Full article

(This article belongs to the Special Issue Metallic and Metal Oxide Nanoparticles and Their Applications)

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13 pages, 628 KiB

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Metal and Metal Oxide Nanoparticles in Caries Prevention: A Review

by Mohammed Zahedul Islam Nizami, Veena W. Xu, Iris X. Yin, Ollie Y. Yu and Chun-Hung Chu

Nanomaterials 2021, 11(12), 3446; https://doi.org/10.3390/nano11123446 - 20 Dec 2021

Cited by 31 | Viewed by 4881

Abstract

Nanoparticles based on metal and metallic oxide have become a novel trend for dental use as they interfere with bacterial metabolism and prevent biofilm formation. Metal and metal oxide nanoparticles demonstrate significant antimicrobial activity by metal ion release, oxidative stress induction and non-oxidative [...] Read more.

Nanoparticles based on metal and metallic oxide have become a novel trend for dental use as they interfere with bacterial metabolism and prevent biofilm formation. Metal and metal oxide nanoparticles demonstrate significant antimicrobial activity by metal ion release, oxidative stress induction and non-oxidative mechanisms. Silver, zinc, titanium, copper, and magnesium ions have been used to develop metal and metal oxide nanoparticles. In addition, fluoride has been used to functionalise the metal and metal oxide nanoparticles. The fluoride-functionalised nanoparticles show fluoride-releasing properties that enhance apatite formation, promote remineralisation, and inhibit demineralisation of enamel and dentine. The particles’ nanoscopic size increases their surface-to-volume ratio and bioavailability. The increased surface area facilitates their mechanical bond with tooth tissue. Therefore, metal and metal oxide nanoparticles have been incorporated in dental materials to strengthen the mechanical properties of the materials and to prevent caries development. Another advantage of metal and metal oxide nanoparticles is their easily scalable production. The aim of this study is to provide an overview of the use of metal and metal oxide nanoparticles in caries prevention. The study reviews their effects on dental materials regarding antibacterial, remineralising, aesthetic, and mechanical properties. Full article

(This article belongs to the Special Issue Metallic and Metal Oxide Nanoparticles and Their Applications)

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13 pages, 2892 KiB

Open AccessReview

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

by Valentina G. Matveeva and Lyudmila M. Bronstein

Nanomaterials 2021, 11(9), 2257; https://doi.org/10.3390/nano11092257 - 31 Aug 2021

Cited by 19 | Viewed by 2524

Abstract

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 [...] Read more.

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. Full article

(This article belongs to the Special Issue Metallic and Metal Oxide Nanoparticles and Their Applications)

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33 pages, 25265 KiB

Open AccessReview

Ga Based Particles, Alloys and Composites: Fabrication and Applications

by Zhi Li, Yiming Guo, Yufen Zong, Kai Li, Shuang Wang, Hai Cao and Chao Teng

Nanomaterials 2021, 11(9), 2246; https://doi.org/10.3390/nano11092246 - 30 Aug 2021

Cited by 11 | Viewed by 4528

Abstract

Liquid metal (LM) materials, including pure gallium (Ga) LM, eutectic alloys and their composites with organic polymers and inorganic nanoparticles, are cutting-edge functional materials owing to their outstanding electrical conductivity, thermal conductivity, extraordinary mechanical compliance, deformability and excellent biocompatibility. The unique properties of [...] Read more.

Liquid metal (LM) materials, including pure gallium (Ga) LM, eutectic alloys and their composites with organic polymers and inorganic nanoparticles, are cutting-edge functional materials owing to their outstanding electrical conductivity, thermal conductivity, extraordinary mechanical compliance, deformability and excellent biocompatibility. The unique properties of LM-based materials at room temperatures can overcome the drawbacks of the conventional electronic devices, particularly high thermal, electrical conductivities and their fluidic property, which would open tremendous opportunities for the fundamental research and practical applications of stretchable and wearable electronic devices. Therefore, research interest has been increasingly devoted to the fabrication methodologies of LM nanoparticles and their functional composites. In this review, we intend to present an overview of the state-of-art protocols for the synthesis of Ga-based materials, to introduce their potential applications in the fields ranging from wearable electronics, energy storage batteries and energy harvesting devices to bio-applications, and to discuss challenges and opportunities in future studies. Full article

(This article belongs to the Special Issue Metallic and Metal Oxide Nanoparticles and Their Applications)

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14 pages, 14895 KiB

Open AccessReview

Research Progress and Prospects of Nanozyme-Based Glucose Biofuel Cells

by Phan Gia Le and Moon Il Kim

Nanomaterials 2021, 11(8), 2116; https://doi.org/10.3390/nano11082116 - 19 Aug 2021

Cited by 19 | Viewed by 3883

Abstract

The appearance and evolution of biofuel cells can be categorized into three groups: microbial biofuel cells (MBFCs), enzymatic biofuel cells (EBFCs), and enzyme-like nanomaterial (nanozyme)-based biofuel cells (NBFCs). MBFCs can produce electricity from waste; however, they have significantly low power output as well [...] Read more.

The appearance and evolution of biofuel cells can be categorized into three groups: microbial biofuel cells (MBFCs), enzymatic biofuel cells (EBFCs), and enzyme-like nanomaterial (nanozyme)-based biofuel cells (NBFCs). MBFCs can produce electricity from waste; however, they have significantly low power output as well as difficulty in controlling electron transfer and microbial growth. EBFCs are more productive in generating electricity with the assistance of natural enzymes, but their vulnerability under diverse environmental conditions has critically hindered practical applications. In contrast, because of the intrinsic advantages of nanozymes, such as high stability and robustness even in harsh conditions, low synthesis cost through facile scale-up, and tunable catalytic activity, NBFCs have attracted attention, particularly for developing wearable and implantable devices to generate electricity from glucose in the physiological fluids of plants, animals, and humans. In this review, recent studies on NBFCs, including the synthetic strategies and catalytic activities of metal and metal oxide-based nanozymes, the mechanism of electricity generation from glucose, and representative studies are reviewed and discussed. Current challenges and prospects for the utilization of nanozymes in glucose biofuel cells are also discussed. Full article

(This article belongs to the Special Issue Metallic and Metal Oxide Nanoparticles and Their Applications)

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