Nanomaterials

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5 pages, 184 KiB

Open AccessEditorial

Morphological Design and Synthesis of Nanoparticles

by Mirela Honciuc and Andrei Honciuc

Nanomaterials 2024, 14(4), 360; https://doi.org/10.3390/nano14040360 - 15 Feb 2024

Cited by 1 | Viewed by 1394

Abstract

Nanoparticles are particles with dimensions measured in nanometers, and exist at a scale where the physical, chemical, and biological properties of materials can differ significantly from those at a larger scale [...] Full article

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

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17 pages, 3806 KiB

Open AccessArticle

Antifungal Activity and Molecular Mechanisms of Copper Nanoforms against Colletotrichum gloeosporioides

by Mun’delanji C. Vestergaard, Yuki Nishida, Lihn T. T. Tran, Neha Sharma, Xiaoxiao Zhang, Masayuki Nakamura, Auriane F. Oussou-Azo and Tomoki Nakama

Nanomaterials 2023, 13(23), 2990; https://doi.org/10.3390/nano13232990 - 22 Nov 2023

Cited by 2 | Viewed by 1870

Abstract

In this work, we have synthesized copper nanoforms (Cu NFs) using ascorbic acid as a reducing agent and polyvinylpyrrolidone as a stabilizer. Elemental characterization using EDS has shown the nanostructure to be of high purity and compare well with commercially sourced nanoforms. SEM [...] Read more.

In this work, we have synthesized copper nanoforms (Cu NFs) using ascorbic acid as a reducing agent and polyvinylpyrrolidone as a stabilizer. Elemental characterization using EDS has shown the nanostructure to be of high purity and compare well with commercially sourced nanoforms. SEM images of both Cu NFs show some agglomeration. The in-house NFs had a better even distribution and size of the nanostructures. The XRD peaks represented a face-centered cubic structure of Cu₂O. The commercially sourced Cu NFs were found to be a mixture of Cu and Cu₂O. Both forms had a crystalline structure. Using these two types of Cu NFs, an antimicrobial study against Colletotrichum gloeosporioides, a devastating plant pathogen, showed the in-house Cu NFs to be most effective at inhibiting growth of the pathogen. Interestingly, at low concentrations, both Cu NFs increased fungal growth, although the mycelia appeared thin and less dense than in the control. SEM macrographs showed that the in-house Cu NFs inhibited the fungus by flattening the mycelia and busting some of them. In contrast, the mycelia were short and appeared clustered when exposed to commercial Cu NFs. The difference in effect was related to the size and/or oxidation state of the Cu NFs. Furthermore, the fungus produced a defense mechanism in response to the NFs. The fungus produced melanin, with the degree of melanization directly corresponding to the concentration of the Cu NFs. Localization of aggregated Cu NFs could be clearly observed outside of the model membranes. The large agglomerates may only contribute indirectly by a hit-and-bounce-off effect, while small structures may adhere to the membrane surface and/or internalize. Spatio-temporal membrane dynamics were captured in real time. The dominant dynamics culminated into large fluctuations. Some of the large fluctuations resulted in vesicular transformation. The major transformation was exo-bud/exo-cytosis, which may be a way to excrete the foreign object (Cu NFs). Full article

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

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18 pages, 6776 KiB

Open AccessArticle

Water-Floating Hydrogel Polymer Microsphere Composites for Application in Hydrological Mining of Cu(II) Ions

by Andrei Honciuc, Ana-Maria Solonaru and Mirela Honciuc

Nanomaterials 2023, 13(19), 2619; https://doi.org/10.3390/nano13192619 - 22 Sep 2023

Cited by 3 | Viewed by 1280

Abstract

Innovative materials and technologies capable of extraction and recovery of technologically relevant metal ions from various water sources, such as lakes, oceans, ponds, or wastewater reservoirs, are in great demand. Polymer beads are among the most well-known solid-phase adsorbents and ion exchangers employed [...] Read more.

Innovative materials and technologies capable of extraction and recovery of technologically relevant metal ions from various water sources, such as lakes, oceans, ponds, or wastewater reservoirs, are in great demand. Polymer beads are among the most well-known solid-phase adsorbents and ion exchangers employed in metal ion recovery. On the other hand, hydrogels are an emerging platform for producing innovative adsorbents, which are environmentally friendly and biocompatible materials. In this work, we take advantage of both technologies and produce a new type of material by loading nanostructured polymer microsphere adsorbent into a PVA matrix to obtain a hydrogel polymer microsphere (HPM) composite in the form of a block. The main role of the poly(4-vinylpyrridine-co-methacrylic acid) microspheres is to adsorb metal ions, such as Cu(II), from model water samples. The secondary role of these microspheres in the hydrogel is to change the hydrogel morphology by softening it and stabilizing it under a foam-like morphology. The foam-like morphology endows these composites with the capability of floating on water surfaces. In this work, we report, for the first time, an HPM composite capable of floating on water surfaces and extracting Cu(II) ions from model water samples. This could enable more environmentally friendly hydrological mining technologies by simply deploying adsorbents on water surfaces for metal ion extraction and recovery, thus eliminating the need for water pumping and mechanical processing steps. Full article

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

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14 pages, 6040 KiB

Open AccessArticle

Liquid-Phase Partial Hydrogenation of Phenylacetylene at Ambient Conditions Catalyzed by Pd-Fe-O Nanoparticles Supported on Silica

by Anastasiya A. Shesterkina, Olga A. Kirichenko, Olga P. Tkachenko, Alexander L. Kustov and Leonid M. Kustov

Nanomaterials 2023, 13(15), 2247; https://doi.org/10.3390/nano13152247 - 3 Aug 2023

Cited by 1 | Viewed by 1357

Abstract

Catalysts with no hazardous or toxic components are required for the selective hydrogenation of acetylenic bonds in the synthesis of pharmaceuticals, vitamins, nutraceuticals, and fragrances. The present work demonstrates that a high selectivity to alkene can be reached over a Pd-Fe-O/SiO₂ system [...] Read more.

Catalysts with no hazardous or toxic components are required for the selective hydrogenation of acetylenic bonds in the synthesis of pharmaceuticals, vitamins, nutraceuticals, and fragrances. The present work demonstrates that a high selectivity to alkene can be reached over a Pd-Fe-O/SiO₂ system prepared by the co-impregnation of a silica support with a solution of the metal precursors (NH₄)₃[Fe(C₂O₄)₃] and [Pd(NH₃)₄]Cl₂ followed by thermal treatment in hydrogen or in air at 400 °C. A DRIFT spectroscopic study of CO adsorption revealed large shifts in the position of the Pdⁿ⁺-CO bands for this system, indicating the strong effect of Feⁿ⁺ on the Pd electronic state, resulting in a decreased rate of double C=C bond hydrogenation and an increased selectivity of alkyne hydrogenation to alkene. The prepared catalysts consisted of mono- and bimetallic nanoparticles on an SiO₂ carrier and exhibited a selectivity as high as that of the commonly used Lindlar catalyst (which contains such hazardous components as lead and barium), while the activity of the Fe-Pd-O/SiO₂ catalyst was an order of magnitude higher. The hydrogenation of a triple bond over the proposed Pd-Fe catalyst opens the way to selective hydrogenation over nontoxic catalysts with a high yield and productivity. Taking into account a simple procedure of catalyst preparation, this direction provides a rationale for the large-scale implementation of these catalysts. Full article

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

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15 pages, 4724 KiB

Open AccessArticle

Effect of the Elaboration Method on Structural and Optical Properties of Zn_1.33Ga_1.335Sn_0.33O₄:0.5%Cr³⁺ Persistent Luminescent Nanomaterials

by Guanyu Cai, Luidgi Giordano, Cyrille Richard and Bruno Viana

Nanomaterials 2023, 13(15), 2175; https://doi.org/10.3390/nano13152175 - 26 Jul 2023

Cited by 9 | Viewed by 1197

Abstract

Near-infrared (NIR) persistent luminescence (PersL) materials have demonstrated promising developments for applications in many advanced fields due to their unique optical properties. Both high-temperature solid-state (SS) or hydrothermal (HT) methods can successfully be used to prepare PersL materials. In this work, Zn_1.33 [...] Read more.

Near-infrared (NIR) persistent luminescence (PersL) materials have demonstrated promising developments for applications in many advanced fields due to their unique optical properties. Both high-temperature solid-state (SS) or hydrothermal (HT) methods can successfully be used to prepare PersL materials. In this work, Zn_1.33Ga_1.34Sn_0.33O₄:0.5%Cr³⁺ (ZGSO:0.5%Cr³⁺), a newly proposed nanomaterial for bioimaging, was prepared using SS and HT methods. The results show the crystal structure, morphology and optical properties of the samples that were prepared using both methods. Briefly, the crystallite size of the ZGSO:0.5%Cr³⁺ prepared using the SS method is ~3 µm, and as expected, is larger than materials prepared using the HT method. However, the growth process used in the hydrothermal environment promotes the formation of ZGSO:0.5%Cr³⁺ with more uniform shapes and smaller sizes (less than 500 nm). Different diameter ranges of nanoparticles were obtained using HT and ball milling (BM) methods (ranging from 25–50 nm) and by using SS and BM methods (25–200 nm) as well. In addition, the SS-prepared microstructure material has stronger PersL than HT-prepared particles before they go through ball milling to create nanomaterials. On the contrary, after BM treatment, ZGSO:0.5%Cr³⁺ HT and BM NPs present higher PersL and photoluminescence (PL) properties than ZGSO:0.5%Cr³⁺ SS and BM NPs, even though both kinds of NPs present worse PersL and PL compared to the original particles before BM. To summarize: preparation methods, whether by SS or HT, with additional grinding as a second step, can have a significant impact on the morphological and luminescent features of ZGSO:0.5%Cr³⁺ PersL materials. Full article

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

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13 pages, 4232 KiB

Open AccessArticle

Synthesis of Platinum Nanoparticles Supported on Fused Nanosized Carbon Spheres Derived from Sustainable Source for Application in a Hydrogen Generation Reaction

by Erik Biehler, Qui Quach and Tarek M. Abdel-Fattah

Nanomaterials 2023, 13(13), 1994; https://doi.org/10.3390/nano13131994 - 1 Jul 2023

Cited by 7 | Viewed by 1783

Abstract

The dwindling supply of fossil fuels has prompted the search for an alternative energy source that could effectively replace them. Potential renewable energy sources such as solar, wind, tidal, and geothermal are all promising but each has its own drawbacks. Hydrogen gas on [...] Read more.

The dwindling supply of fossil fuels has prompted the search for an alternative energy source that could effectively replace them. Potential renewable energy sources such as solar, wind, tidal, and geothermal are all promising but each has its own drawbacks. Hydrogen gas on the other hand can be combusted to produce energy with only water as a byproduct and can be steadily generated via the aqueous media hydrolysis reaction of Sodium Borohydride (NaBH₄). This study successfully synthesized fused carbon spheres derived from sugar and decorated them with platinum nanoparticles to form a novel composite material (PtFCS) for catalyzing this reaction. The platinum nanoparticles were produced by reducing chloroplatinic acid in a solution with sodium borohydride and using sodium citrate as a capping agent for the nanoparticles. Transmission electron microscopy (TEM), Energy-dispersive X-ray spectroscopy (EDS), Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) were used to characterize and determine the size and shape of the Pt nanoparticles (PtNPs) and fused carbon spheres. TEM was able to determine the average size of the fused carbon spheres to be 200 nm and the average size for the PtNPs to be 2–3 nm. The PtFCS composite was tested for its ability to catalyze the hydrolysis of NaBH₄ under various reaction conditions including various solution pH, various temperatures, and various dosages of sodium borohydride. The catalyst was found to perform the best under acidic solution conditions (pH 6), producing hydrogen at a rate of 0.0438 mL/mg_cat·min. The catalyst was determined to have an activation energy of 53.0 kJ/mol and could be used multiple times in succession with no loss in the volume of hydrogen produced. This sugar-derived composite catalyst shows promise and could be implemented as a sustainable catalyst for the generation of hydrogen fuel. Full article

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

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21 pages, 3282 KiB

Open AccessArticle

Investigation of the Influence of Wound-Treatment-Relevant Buffer Systems on the Colloidal and Optical Properties of Gold Nanoparticles

by Atiđa Selmani, Ramona Jeitler, Michael Auinger, Carolin Tetyczka, Peter Banzer, Brian Kantor, Gerd Leitinger and Eva Roblegg

Nanomaterials 2023, 13(12), 1878; https://doi.org/10.3390/nano13121878 - 17 Jun 2023

Cited by 4 | Viewed by 1676

Abstract

Biocompatible gold nanoparticles (AuNPs) are used in wound healing due to their radical scavenging activity. They shorten wound healing time by, for example, improving re-epithelialization and promoting the formation of new connective tissue. Another approach that promotes wound healing through cell proliferation while [...] Read more.

Biocompatible gold nanoparticles (AuNPs) are used in wound healing due to their radical scavenging activity. They shorten wound healing time by, for example, improving re-epithelialization and promoting the formation of new connective tissue. Another approach that promotes wound healing through cell proliferation while inhibiting bacterial growth is an acidic microenvironment, which can be achieved with acid-forming buffers. Accordingly, a combination of these two approaches appears promising and is the focus of the present study. Here, 18 nm and 56 nm gold NP (Au) were prepared with Turkevich reduction synthesis using design-of-experiments methodology, and the influence of pH and ionic strength on their behaviour was investigated. The citrate buffer had a pronounced effect on the stability of AuNPs due to the more complex intermolecular interactions, which was also confirmed by the changes in optical properties. In contrast, AuNPs dispersed in lactate and phosphate buffer were stable at therapeutically relevant ionic strength, regardless of their size. Simulation of the local pH distribution near the particle surface also showed a steep pH gradient for particles smaller than 100 nm. This suggests that the healing potential is further enhanced by a more acidic environment at the particle surface, making this strategy a promising approach. Full article

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

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15 pages, 8449 KiB

Open AccessArticle

Hard–Soft Core–Shell Architecture Formation from Cubic Cobalt Ferrite Nanoparticles

by Marco Sanna Angotzi, Valentina Mameli, Dominika Zákutná, Fausto Secci, Huolin L. Xin and Carla Cannas

Nanomaterials 2023, 13(10), 1679; https://doi.org/10.3390/nano13101679 - 19 May 2023

Cited by 2 | Viewed by 1649

Abstract

Cubic bi-magnetic hard–soft core–shell nanoarchitectures were prepared starting from cobalt ferrite nanoparticles, prevalently with cubic shape, as seeds to grow a manganese ferrite shell. The combined use of direct (nanoscale chemical mapping via STEM-EDX) and indirect (DC magnetometry) tools was adopted to verify [...] Read more.

Cubic bi-magnetic hard–soft core–shell nanoarchitectures were prepared starting from cobalt ferrite nanoparticles, prevalently with cubic shape, as seeds to grow a manganese ferrite shell. The combined use of direct (nanoscale chemical mapping via STEM-EDX) and indirect (DC magnetometry) tools was adopted to verify the formation of the heterostructures at the nanoscale and bulk level, respectively. The results showed the obtainment of core–shell NPs (CoFe₂O₄@MnFe₂O₄) with a thin shell (heterogenous nucleation). In addition, manganese ferrite was found to homogeneously nucleate to form a secondary nanoparticle population (homogenous nucleation). This study shed light on the competitive formation mechanism of homogenous and heterogenous nucleation, suggesting the existence of a critical size, beyond which, phase separation occurs and seeds are no longer available in the reaction medium for heterogenous nucleation. These findings may allow one to tailor the synthesis process in order to achieve better control of the materials’ features affecting the magnetic behaviour, and consequently, the performances as heat mediators or components for data storage devices. Full article

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

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15 pages, 4961 KiB

Open AccessEditor’s ChoiceArticle

Monitoring the Surface Energy Change of Nanoparticles in Functionalization Reactions with the NanoTraPPED Method

by Andrei Honciuc and Oana-Iuliana Negru

Nanomaterials 2023, 13(7), 1246; https://doi.org/10.3390/nano13071246 - 31 Mar 2023

Cited by 5 | Viewed by 1677

Abstract

Performing chemical functionalization on the surface of nanoparticles underlies their use in applications. Probing that a physicochemical transformation has indeed occurred on a nanoparticles’ surface is rather difficult. For this reason, we propose that a macroscopic parameter, namely the surface energy γ, can [...] Read more.

Performing chemical functionalization on the surface of nanoparticles underlies their use in applications. Probing that a physicochemical transformation has indeed occurred on a nanoparticles’ surface is rather difficult. For this reason, we propose that a macroscopic parameter, namely the surface energy γ, can monitor the physicochemical transformations taking place at the surface of nanoparticles. Determining the surface energy of macroscopic surfaces is trivial, but it is very challenging for nanoparticles. In this work we demonstrate that the Nanoparticles Trapped on Polymerized Pickering Emulsion Droplet (NanoTraPPED) method can be successfully deployed to monitor the evolution of surface energies γ, with its γ^p polar and γ^d dispersive components of the silica nanoparticles at each stage of two surface reactions: (i) amination by siloxane chemistry, coupling reaction of a 2,4-dihydroxy benzaldehyde and formation of a Schiff base ligand, followed by coordination of metal ions and (ii) epoxide ring opening and formation of azide. The change in surface energy and its components are discussed and analyzed for each step of the two reactions. It is observed that large variations in surface energy are observed with the complexity of the molecular structure attaching to nanoparticle surface, while functional group replacement leads to only small changes in the surface energies. Full article

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

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17 pages, 6791 KiB

Open AccessArticle

PEG-Coated MnZn Ferrite Nanoparticles with Hierarchical Structure as MRI Contrast Agent

by Sedigheh Cheraghali, Ghasem Dini, Isabella Caligiuri, Michele Back and Flavio Rizzolio

Nanomaterials 2023, 13(3), 452; https://doi.org/10.3390/nano13030452 - 22 Jan 2023

Cited by 11 | Viewed by 2329

Abstract

In this work, MnZn ferrite nanoparticles with hierarchical morphology were synthesized hydrothermally, and their surface characteristics were improved by the PEGylation process. In vitro MRI studies were also conducted to evaluate the ability of the synthesized nanoparticles as a contrast agent. All results [...] Read more.

In this work, MnZn ferrite nanoparticles with hierarchical morphology were synthesized hydrothermally, and their surface characteristics were improved by the PEGylation process. In vitro MRI studies were also conducted to evaluate the ability of the synthesized nanoparticles as a contrast agent. All results were compared with those obtained for MnZn ferrite nanoparticles with normal structure. Microstructural evaluations showed that in ferrite with hierarchical morphology, the spherical particles with an average size of ~20 nm made a distinctive structure consisting of rows of nanoparticles which is a relatively big assembly like a dandelion. The smaller particle size and dandelion-like morphology led to an increase in specific surface area for the hierarchical structure (~69 m²/g) in comparison to the normal one (~30 m²/g) with an average particle size of ~40 nm. In vitro MRI, cytotoxicity and hemocompatibility assays confirmed the PEG-coated MnZn ferrite nanoparticles with hierarchical structure synthesized in the current study can be considered as an MRI contrast agent. Full article

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

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10 pages, 3937 KiB

Open AccessArticle

Electrochemical Synthesis of Nb-Doped BaTiO₃ Nanoparticles with Titanium-Niobium Alloy as Electrode

by Qi Yuan, Wencai Hu, Tao Wang, Sen Wang, Gaobin Liu, Xueyan Han, Feixiang Guo and Yongheng Fan

Nanomaterials 2023, 13(2), 252; https://doi.org/10.3390/nano13020252 - 6 Jan 2023

Cited by 2 | Viewed by 2062

Abstract

In this paper, Nb-doped BaTiO₃ nanoparticles (BaNb_0.47Ti_0.53O₃) were prepared using an electrochemical method in an alkaline solution, with titanium-niobium alloy as the electrode. The results indicated that under relatively mild conditions (normal temperature and pressure, V [...] Read more.

In this paper, Nb-doped BaTiO₃ nanoparticles (BaNb_0.47Ti_0.53O₃) were prepared using an electrochemical method in an alkaline solution, with titanium-niobium alloy as the electrode. The results indicated that under relatively mild conditions (normal temperature and pressure, V < 60 V, I < 5 A), cubic perovskite phase Nb-doped BaTiO₃ nanoparticles with high crystallinity and uniform distribution can be synthesized. With this increase in alkalinity, the crystallinity of the sample increases, the crystal grain size decreases, and the particles become more equally dispersed. Furthermore, in our study, the average grain size of the nanoparticles was 5–20 nm, and the particles with good crystallinity were obtained at a concentration of 3 mol/L of NaOH. This provides a new idea and method for introducing foreign ions under high alkalinity conditions. Full article

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

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18 pages, 2263 KiB

Open AccessArticle

Solvent Influence on the Magnetization and Phase of Fe-Ni Alloy Nanoparticles Generated by Laser Ablation in Liquids

by Inna Y. Khairani, Qiyuan Lin, Joachim Landers, Soma Salamon, Carlos Doñate-Buendía, Evguenia Karapetrova, Heiko Wende, Giovanni Zangari and Bilal Gökce

Nanomaterials 2023, 13(2), 227; https://doi.org/10.3390/nano13020227 - 4 Jan 2023

Cited by 11 | Viewed by 2223

Abstract

The synthesis of bimetallic iron-nickel nanoparticles with control over the synthesized phases, particle size, surface chemistry, and oxidation level remains a challenge that limits the application of these nanoparticles. Pulsed laser ablation in liquid allows the properties tuning of the generated nanoparticles by [...] Read more.

The synthesis of bimetallic iron-nickel nanoparticles with control over the synthesized phases, particle size, surface chemistry, and oxidation level remains a challenge that limits the application of these nanoparticles. Pulsed laser ablation in liquid allows the properties tuning of the generated nanoparticles by changing the ablation solvent. Organic solvents such as acetone can minimize nanoparticle oxidation. Yet, economical laboratory and technical grade solvents that allow cost-effective production of FeNi nanoparticles contain water impurities, which are a potential source of oxidation. Here, we investigated the influence of water impurities in acetone on the properties of FeNi nanoparticles generated by pulsed laser ablation in liquids. To remove water impurities and produce “dried acetone”, cost-effective and reusable molecular sieves (3 Å) are employed. The results show that the Fe₅₀Ni₅₀ nanoparticles’ properties are influenced by the water content of the solvent. The metastable HCP FeNi phase is found in NPs prepared in acetone, while only the FCC phase is observed in NPs formed in water. Mössbauer spectroscopy revealed that the FeNi nanoparticles oxidation in dried acetone is reduced by 8% compared to acetone. The high-field magnetization of Fe₅₀Ni₅₀ nanoparticles in water is the highest, 68 Am²/kg, followed by the nanoparticles obtained after ablation in acetone without water impurities, 59 Am²/kg, and acetone, 52 Am²/kg. The core-shell structures formed in these three liquids are also distinctive, demonstrating that a core-shell structure with an outer oxide layer is formed in water, while carbon external layers are obtained in acetone without water impurity. The results confirm that the size, structure, phase, and oxidation of FeNi nanoparticles produced by pulsed laser ablation in liquids can be modified by changing the solvent or just reducing the water impurities in the organic solvent. Full article

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

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10 pages, 2075 KiB

Open AccessArticle

Hydrothermal Synthesis and Properties of Yb³⁺/Tm³⁺ Doped Sr₂LaF₇ Upconversion Nanoparticles

by Bojana Milićević, Jovana Periša, Zoran Ristić, Katarina Milenković, Željka Antić, Krisjanis Smits, Meldra Kemere, Kaspars Vitols, Anatolijs Sarakovskis and Miroslav D. Dramićanin

Nanomaterials 2023, 13(1), 30; https://doi.org/10.3390/nano13010030 - 21 Dec 2022

Cited by 4 | Viewed by 1771

Abstract

We report the procedure for hydrothermal synthesis of ultrasmall Yb³⁺/Tm³⁺ co-doped Sr₂LaF₇ (SLF) upconversion phosphors. These phosphors were synthesized by varying the concentrations of Yb³⁺ (x = 10, 15, 20, and 25 mol%) and Tm³⁺ [...] Read more.

We report the procedure for hydrothermal synthesis of ultrasmall Yb³⁺/Tm³⁺ co-doped Sr₂LaF₇ (SLF) upconversion phosphors. These phosphors were synthesized by varying the concentrations of Yb³⁺ (x = 10, 15, 20, and 25 mol%) and Tm³⁺ (y = 0.75, 1, 2, and 3 mol%) with the aim to analyze their emissions in the near IR spectral range. According to the detailed structural analysis, Yb³⁺ and Tm³⁺ occupy the La³⁺ sites in the SLF host. The addition of Yb³⁺/Tm³⁺ ions has a huge impact on the lattice constant, particle size, and PL emission properties of the synthesized SLF nanophosphor. The results show that the optimal dopant concentrations for upconversion luminescence of Yb³⁺/Tm³⁺ co-doped SLF are 20 mol% Yb³⁺ and 1 mol% Tm³⁺ with EDTA as the chelating agent. Under 980 nm light excitation, a strong upconversion emission of Tm³⁺ ions around 800 nm was achieved. In addition, the experimental photoluminescence lifetime of Tm³⁺ emission in the SLF host is reported. This study discovered that efficient near IR emission from ultrasmall Yb³⁺/Tm³⁺ co-doped SLF phosphors may have potential applications in the fields of fluorescent labels in bioimaging and security applications. Full article

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

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14 pages, 4450 KiB

Open AccessArticle

Extraction of Metal Ions by Interfacially Active Janus Nanoparticles Supported by Wax Colloidosomes Obtained from Pickering Emulsions

by Oliver Pauli and Andrei Honciuc

Nanomaterials 2022, 12(21), 3738; https://doi.org/10.3390/nano12213738 - 25 Oct 2022

Cited by 3 | Viewed by 1898

Abstract

Most common wastewater treatment technologies for ion extraction and recovery rely on pumping wastewater through ion-exchange columns, filled with surface-functionalized polymer microspheres. To avoid the energetically intensive process of pumping large quantities of water through ion-exchange columns, alternative technologies are being developed, such [...] Read more.

Most common wastewater treatment technologies for ion extraction and recovery rely on pumping wastewater through ion-exchange columns, filled with surface-functionalized polymer microspheres. To avoid the energetically intensive process of pumping large quantities of water through ion-exchange columns, alternative technologies are being developed, such as water-floating membranes containing ligands. In this context, innovative materials could be deployed. Here, we report nanostructured paraffine wax microspheres capable of floating on water, a design based on Pickering emulsion technology, where Janus nanoparticles act both as emulsion stabilizers and as ligand carriers. In the process of emulsification of molten wax in water, followed by cooling, the branched polyethylenimine (bPEI) carrying Janus nanoparticles are trapped at the molten wax/water interface, forming spherical microspheres or colloidosomes decorated with nanoparticles. The paraffine wax colloidosomes stabilized by ligand-carrying Janus nanoparticles are capable of floating on water and show high metal ion extraction capacities towards Cr(VI), Co(II), Ni(II), Cu(II) and Zn(II). In addition, we demonstrate that the ions can be recovered from the colloidosomes and that the colloidosomes can withstand several extraction/recovery cycles with little or no loss in the absorption capacity. Full article

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

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10 pages, 2196 KiB

Open AccessEditor’s ChoiceArticle

A Versatile Route for Synthesis of Metal Nanoalloys by Discharges at the Interface of Two Immiscible Liquids

by Ahmad Hamdan and Luc Stafford

Nanomaterials 2022, 12(20), 3603; https://doi.org/10.3390/nano12203603 - 14 Oct 2022

Cited by 4 | Viewed by 1341

Abstract

Discharge in liquid is a promising technique to produce nanomaterials by electrode erosion. Although its feasibility was demonstrated in many conditions, the production of nanoalloys by in-liquid discharges remains a challenge. Here, we show that spark discharge in liquid cyclohexane that is in [...] Read more.

Discharge in liquid is a promising technique to produce nanomaterials by electrode erosion. Although its feasibility was demonstrated in many conditions, the production of nanoalloys by in-liquid discharges remains a challenge. Here, we show that spark discharge in liquid cyclohexane that is in contact with conductive solution, made of a combination of Ni-nitrate and/or Fe-nitrate and/or Co-nitrate, is suitable to produce nanoalloys (<10 nm) of Ni-Fe, Ni-Co, Co-Fe, and Ni-Co-Fe. The nanoparticles are synthesized by the reduction of metal ions during discharge, and they are individually embedded in C-matrix; this latter originates from the decomposition of cyclohexane. The results open novel ways to produce a wide spectrum of nanoalloys; they are needed for many applications, such as in catalysis, plasmonic, and energy conversion. Full article

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

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20 pages, 9891 KiB

Open AccessArticle

High Strength Die-Attach Joint Formation by Pressureless Sintering of Organic Amine Modified Ag Nanoparticle Paste

by Xingwang Shen, Junjie Li and Shuang Xi

Nanomaterials 2022, 12(19), 3351; https://doi.org/10.3390/nano12193351 - 26 Sep 2022

Cited by 6 | Viewed by 4323

Abstract

Sintered silver (Ag) die-attach has attracted much attention in power systems with high power density and high operating temperature. In this paper, we proposed a novel surface modification method for Ag nanoparticles with organic amines as a coating agent for enhancing the pressureless [...] Read more.

Sintered silver (Ag) die-attach has attracted much attention in power systems with high power density and high operating temperature. In this paper, we proposed a novel surface modification method for Ag nanoparticles with organic amines as a coating agent for enhancing the pressureless sintering performance. This work systematically introduced the Ag nanoparticle modification process, Ag paste preparation, and sintering process and compared the changes in the sintering performance of Ag nanoparticles after modification with four different alkyl chain lengths of amines. The study showed that the sintered films of Ag nanoparticle pastes modified with n-octylamine (NOA) can achieve the lowest resistivity of the sintered film and the highest shear strength of the bonded joints. The resistivity of the sintered Ag film is affected by the grain size and microscopic morphology, and the strength of the bonded joints is also related to the sintering density and the amount of organic residues. The thermal behavior of the Ag particles coated with different amines is measured by thermal analysis. Finally, the mechanism of NOA-modified Ag nanoparticles to improve the sintering performance is proposed. This study can provide effective data and theoretical support for the further promotion and application of nano-Ag pressureless sintering. Full article

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

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12 pages, 788 KiB

Open AccessArticle

Nonlinear Optical Rectification in an Inversion-Symmetry-Broken Molecule near a Metallic Nanoparticle

by Natalia Domenikou, Ioannis Thanopulos, Vassilios Yannopapas and Emmanuel Paspalakis

Nanomaterials 2022, 12(6), 1020; https://doi.org/10.3390/nano12061020 - 21 Mar 2022

Cited by 6 | Viewed by 2006

Abstract

We study the nonlinear optical rectification of an inversion-symmetry-broken quantum system interacting with an optical field near a metallic nanoparticle, exemplified in a polar zinc–phthalocyanine molecule in proximity to a gold nanosphere. The corresponding nonlinear optical rectification coefficient under external strong field excitation [...] Read more.

We study the nonlinear optical rectification of an inversion-symmetry-broken quantum system interacting with an optical field near a metallic nanoparticle, exemplified in a polar zinc–phthalocyanine molecule in proximity to a gold nanosphere. The corresponding nonlinear optical rectification coefficient under external strong field excitation is derived using the steady-state solution of the density matrix equations. We use ab initio electronic structure calculations for determining the necessary spectroscopic data of the molecule under study, as well as classical electromagnetic calculations for obtaining the influence of the metallic nanoparticle to the molecular spontaneous decay rates and to the external electric field applied to the molecule. The influence of the metallic nanoparticle to the optical rectification coefficient of the molecule is investigated by varying several parameters of the system, such as the intensity and polarization of the incident field, as well as the distance of the molecule from the nanoparticle, which indirectly affects the molecular pure dephasing rate. We find that the nonlinear optical rectification coefficient can be greatly enhanced for particular incident-field configurations and at optimal distances between the molecule and the metallic nanoparticle. Full article

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

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37 pages, 6781 KiB

Open AccessReview

Current Applications of Liposomes for the Delivery of Vitamins: A Systematic Review

by Matheus A. Chaves, Letícia S. Ferreira, Lucia Baldino, Samantha C. Pinho and Ernesto Reverchon

Nanomaterials 2023, 13(9), 1557; https://doi.org/10.3390/nano13091557 - 5 May 2023

Cited by 16 | Viewed by 5331

Abstract

Liposomes have been used for several decades for the encapsulation of drugs and bioactives in cosmetics and cosmeceuticals. On the other hand, the use of these phospholipid vesicles in food applications is more recent and is increasing significantly in the last ten years. [...] Read more.

Liposomes have been used for several decades for the encapsulation of drugs and bioactives in cosmetics and cosmeceuticals. On the other hand, the use of these phospholipid vesicles in food applications is more recent and is increasing significantly in the last ten years. Although in different stages of technological maturity—in the case of cosmetics, many products are on the market—processes to obtain liposomes suitable for the encapsulation and delivery of bioactives are highly expensive, especially those aiming at scaling up. Among the bioactives proposed for cosmetics and food applications, vitamins are the most frequently used. Despite the differences between the administration routes (oral for food and mainly dermal for cosmetics), some challenges are very similar (e.g., stability, bioactive load, average size, increase in drug bioaccessibility and bioavailability). In the present work, a systematic review of the technological advancements in the nanoencapsulation of vitamins using liposomes and related processes was performed; challenges and future perspectives were also discussed in order to underline the advantages of these drug-loaded biocompatible nanocarriers for cosmetics and food applications. Full article

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

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47 pages, 6900 KiB

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Metal Nanoparticle-Flavonoid Connections: Synthesis, Physicochemical and Biological Properties, as Well as Potential Applications in Medicine

by Stepan Sysak, Beata Czarczynska-Goslinska, Piotr Szyk, Tomasz Koczorowski, Dariusz T. Mlynarczyk, Wojciech Szczolko, Roman Lesyk and Tomasz Goslinski

Nanomaterials 2023, 13(9), 1531; https://doi.org/10.3390/nano13091531 - 2 May 2023

Cited by 18 | Viewed by 3671

Abstract

Flavonoids are polyphenolic compounds widely occurring throughout the plant kingdom. They are biologically active and have many medical applications. Flavonoids reveal chemopreventive, anticarcinogenic, and antioxidant properties, as well as being able to modulate the immune system response and inhibit inflammation, angiogenesis, and metastasis. [...] Read more.

Flavonoids are polyphenolic compounds widely occurring throughout the plant kingdom. They are biologically active and have many medical applications. Flavonoids reveal chemopreventive, anticarcinogenic, and antioxidant properties, as well as being able to modulate the immune system response and inhibit inflammation, angiogenesis, and metastasis. Polyphenols are also believed to reverse multidrug resistance via various mechanisms, induce apoptosis, and activate cell death signals in tumor cells by modulating cell signaling pathways. The main limitation to the broader usage of flavonoids is their low solubility, poor absorption, and rapid metabolism. To tackle this, the combining of flavonoids with nanocarriers could improve their bioavailability and create systems of wider functionalities. Recently, interest in hybrid materials based on combinations of metal nanoparticles with flavonoids has increased due to their unique physicochemical and biological properties, including improved selectivity toward target sites. In addition, flavonoids have further utilities, even in the initial step of preparation of metal nanomaterials. The review offers knowledge on multiple possibilities of the synthesis of flavonoid-metal nanoparticle conjugates, as well as presents some of their features such as size, shape, surface charge, and stability. The flavonoid-metal nanoparticles are also discussed regarding their biological properties and potential medical applications. Full article

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

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