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17 pages, 7386 KiB

Open AccessArticle

Synthesis and Characterization of Magnetite/Gold Core Shell Nanoparticles Stabilized with a β-Cyclodextrin Nanosponge to Develop a Magneto-Plasmonic System

by Sebastián Salazar Sandoval, Daniel Santibáñez, Ana Riveros, Fabián Araneda, Tamara Bruna, Nataly Silva, Nicolás Yutronic, Marcelo J. Kogan and Paul Jara

Magnetochemistry 2023, 9(8), 202; https://doi.org/10.3390/magnetochemistry9080202 - 09 Aug 2023

Viewed by 1576

Abstract

Magnetite/gold core-shell nanoparticles (magnetite/gold NPs) have important optical and magnetic properties that provide potential for applications, especially biomedical ones. However, their preparation is not exempt from difficulties that might lead to unexpected or undesired structures. This work reports the synthesis and characterization of [...] Read more.

Magnetite/gold core-shell nanoparticles (magnetite/gold NPs) have important optical and magnetic properties that provide potential for applications, especially biomedical ones. However, their preparation is not exempt from difficulties that might lead to unexpected or undesired structures. This work reports the synthesis and characterization of magnetite/gold NPs using tetramethylammonium hydroxide (TMAH) to promote the formation of a continuous interface between the magnetite core and the thin gold shell. The synthesized magnetite/gold NPs were characterized using transmission electron microscopy (TEM), energy-dispersive spectroscopy (EDS), field emission scanning electron microscope (FE-SEM), ζ-potential, vibrating sample magnetometer (VSM), selected area electron diffraction (SAED), UV-Visible spectroscopy, and dynamic light scattering (DLS), confirming the core-shell structure of the NPs with narrow size distribution while evidencing its plasmonic and superparamagnetic properties as well. Further, the magnetite/gold NPs were associated and stabilized with a β-cyclodextrin nanosponge (β-CDNSs), obtaining a versatile magneto-plasmonic system for potential applications in the encapsulation and controlled release of drugs. Full article

(This article belongs to the Special Issue Advances in Magnetic Nanomaterials and Nanostructures)

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13 pages, 398 KiB

Open AccessArticle

Magnetoelectric Coupling Effects in Tb-Doped BiFeO₃ Nanoparticles

by Iliana Apostolova, Angel Apostolov and Julia Wesselinowa

Magnetochemistry 2023, 9(6), 142; https://doi.org/10.3390/magnetochemistry9060142 - 26 May 2023

Cited by 2 | Viewed by 928

Abstract

The magnetic, electric, and optical properties in Tb-doped BiFeO₃ nanoparticles as functions of size and doping concentrations were investigated using a microscopic model, taking into account both linear and quadratic magnetoelectric (ME) coupling. We observed improved multiferroic properties and band-gap tuning. The [...] Read more.

The magnetic, electric, and optical properties in Tb-doped BiFeO₃ nanoparticles as functions of size and doping concentrations were investigated using a microscopic model, taking into account both linear and quadratic magnetoelectric (ME) coupling. We observed improved multiferroic properties and band-gap tuning. The magnetization and polarization increased with the decreased nanoparticle size and increased Tb-doping substitution x. The Neel temperature remained nearly unchanged whereas the Curie temperature was reduced with the increased x. There was doping-induced ME coupling. The dielectric constant is discussed as a function of the size, doping, and the magnetic field. The band gap decreased with the decreased size or increased Tb dopants due to competing effects of the compressive strain, oxygen defects on the surface, and Coulomb interactions. Increasing the Tb dopants and decreasing the nanoparticle size improved the ME effect. Full article

(This article belongs to the Special Issue Advances in Magnetic Nanomaterials and Nanostructures)

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11 pages, 2289 KiB

Open AccessArticle

Hydrothermal Synthesis and Magnetic Properties of Zn/Mn Oxides Nano Particles

by Izabela Kuryliszyn-Kudelska, Witold Dobrowolski, Monika Arciszewska, Branka Hadžić, Nebojsa Romčević, Maja Romčević, Daniel Sibera and Urszula Narkiewicz

Magnetochemistry 2023, 9(6), 139; https://doi.org/10.3390/magnetochemistry9060139 - 25 May 2023

Viewed by 1079

Abstract

The aim of this study was to investigate the magnetic properties of mixed nanocrystalline Zn/manganese oxide compounds synthesized by a hydrothermal method. These compounds are designed as (ZnO)_1−n(MnO)_n, where index n ranges from 0.05 to 0.60. The results of [...] Read more.

The aim of this study was to investigate the magnetic properties of mixed nanocrystalline Zn/manganese oxide compounds synthesized by a hydrothermal method. These compounds are designed as (ZnO)_1−n(MnO)_n, where index n ranges from 0.05 to 0.60. The results of magnetic measurements, including AC magnetic susceptibility as a function of temperature (up to 160 K) and frequency (from 7 Hz up to 9970 Hz), as well as DC magnetization in magnetic fields up to 9 T and temperature up to 50 K, are reported. We observed various types of magnetic behavior depending on the nominal weight content of MnO. Samples with a low nominal content (up to n = 0.10) of MnO exhibited Curie–Weiss behavior at higher temperatures. For samples with high nominal weight contribution (from n = 0.30 to 0.60), spin-glass-like or/and weak ferromagnetic behavior is observed. Full article

(This article belongs to the Special Issue Advances in Magnetic Nanomaterials and Nanostructures)

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19 pages, 3989 KiB

Open AccessFeature PaperArticle

Influence of Mn Doping on Local Spin Moments and Stacking Fault Energies in Co(Mn) Alloys

by Kayla Cole-Piepke, Prabandha Nakarmi, Alicia Koenig, Gregory B. Thompson, Tim Mewes, Claudia Mewes, Ronald Noebe and Alex Leary

Magnetochemistry 2023, 9(6), 138; https://doi.org/10.3390/magnetochemistry9060138 - 23 May 2023

Viewed by 966

Abstract

We report on the results of first principles calculations investigating the influences of Mn doping on the local moments and stacking fault energies (SFEs) in the Co

_{95.8}

Mn

_{4.2}

and Co

_{91.6}

Mn

_{8.4}

systems as compared to pure face-centered cubic Co. [...] Read more.

We report on the results of first principles calculations investigating the influences of Mn doping on the local moments and stacking fault energies (SFEs) in the Co

_{95.8}

Mn

_{4.2}

and Co

_{91.6}

Mn

_{8.4}

systems as compared to pure face-centered cubic Co. A supercell was developed to maintain periodicity in calculations, provide a simple relaxation mechanism, and allow for easy expansion to accommodate different concentrations of Mn. Calculations to determine the generalized SFE were performed on relaxed and non-relaxed systems in both ferromagnetic and nonmagnetic states. Analysis revealed fluctuations in the magnetic moments that are closely tied to the relaxation state and faulting state of the system. In the case of systems containing Mn, we observed a dependence of the SFE on the location of the Mn atom(s) within the supercell relative to the stacking fault interface and a strong induced magnetic moment for these atoms. Full article

(This article belongs to the Special Issue Advances in Magnetic Nanomaterials and Nanostructures)

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17 pages, 4633 KiB

Open AccessArticle

Magnetic Hyperthermia and Antibacterial Response of CuCo₂O₄ Nanoparticles Synthesized through Laser Ablation of Bulk Alloy

by Imran Ali, Yasir Jamil, Saeed Ahmed Khan, Yunxiang Pan, Aqeel Ahmed Shah, Ali Dad Chandio, Sadaf Jamal Gilani, May Nasser Bin Jumah, Yusra Fazal, Jun Chen and Zhonghua Shen

Magnetochemistry 2023, 9(3), 68; https://doi.org/10.3390/magnetochemistry9030068 - 27 Feb 2023

Viewed by 1885

Abstract

The wide variety of uses for nanoparticles (NPs) is due to their unique combination of features in a single assembly. The arc melted copper-cobalt ingot sample were qualitatively studied using laser induced breakdown spectroscopy (LIBS). Later, using the fabricated alloy as a target [...] Read more.

The wide variety of uses for nanoparticles (NPs) is due to their unique combination of features in a single assembly. The arc melted copper-cobalt ingot sample were qualitatively studied using laser induced breakdown spectroscopy (LIBS). Later, using the fabricated alloy as a target material for Nd:YAG laser ablation, CuCo₂O₄ NPs were synthesized. The magnetic properties of the synthesized NPs were studied using a vibrating sample magnetometer (VSM). To determine the composition and morphology of the synthesized NPs, X-ray diffraction (XRD), energy dispersive X-ray (EDX) analysis, transmission electron microscopy (TEM), scanning electron microscopy (SEM), and dynamic light scattering (DLS) techniques were used. The TEM and DLS showed that particles were spherical in shape with an average size of 32 nm and 28 nm, respectively. The antibacterial activity of the synthesized NPs was studied against S. aureus and E. coli strains as positive and negative controls using a standard approach. CuCo₂O₄ nanoparticles exhibited non-mutagenic potential against S. typhimurium TA-98 and TA-100 strains. Furthermore, the magnetic hyperthermia study of CuCo₂O₄ nanofluid was examined using a lab-made apparatus. The specific absorption rates (SAR) of 4.57 and 5.17 W/g were determined for the magnetic field strength of 230 μT and 247 μT, respectively. The study shows antibacterial activity and magnetic hyperthermia potential of the synthesized nanoparticles. Full article

(This article belongs to the Special Issue Advances in Magnetic Nanomaterials and Nanostructures)

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22 pages, 6753 KiB

Open AccessFeature PaperArticle

Structure and Magnetism of Iron-Substituted Nickel Hydroxide Nanosheets

by Samuel W. Kimmel, Barry D. Koehne, Ben Gibson, Wilhelmus J. Geerts, Nikoleta Theodoropoulou and Christopher P. Rhodes

Magnetochemistry 2023, 9(1), 25; https://doi.org/10.3390/magnetochemistry9010025 - 08 Jan 2023

Cited by 1 | Viewed by 2709

Abstract

Nanosheets composed of stacked atomic layers exhibit unique magnetic, electrical, and electrochemical properties. Here, we report the effect of iron substitution on the structure and magnetism of nickel hydroxide, Ni(OH)₂, nanosheets. Ni(OH)₂ and iron-substituted Ni(OH)₂ (5, 10, 20, and [...] Read more.

Nanosheets composed of stacked atomic layers exhibit unique magnetic, electrical, and electrochemical properties. Here, we report the effect of iron substitution on the structure and magnetism of nickel hydroxide, Ni(OH)₂, nanosheets. Ni(OH)₂ and iron-substituted Ni(OH)₂ (5, 10, 20, and 50 atomic % Fe substitution) were synthesized using a rapid microwave-assisted hydrothermal process. Scanning and transmission electron microscopy show the materials are polycrystalline nanosheets that aggregate into micron-sized clusters. From X-ray diffraction characterization, iron substitutes into the α-Ni(OH)₂ lattice up to 20 at. % substitution. The nanosheets exhibit different in-plane and through-plane domain sizes, and Fe substitution affects the nanocrystallite shape anisotropy. The magnetic response differs with Fe substitution: 0% and 5% Fe are ferromagnetic, while samples with 10% and 20% Fe are ferrimagnetic. The competing interactions between magnetization sublattices and the magnetic anisotropy due to the crystalline and shape anisotropy of the nanosheets lead to magnetization reversal at low temperatures. The correlation between higher coercivity and larger nanocrystalline size anisotropy with higher Fe % supports that magnetic anisotropy contributes to the observed ferrimagnetism. The interplay of morphology and magnetic response with Fe-substituted Ni(OH)₂ nanosheets points to new ways to influence electron interactions in layered materials which has implications for batteries, catalysis, sensors, and electronics. Full article

(This article belongs to the Special Issue Advances in Magnetic Nanomaterials and Nanostructures)

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13 pages, 1101 KiB

Open AccessArticle

On the Distribution of Magnetic Moments in a System of Magnetic Nanoparticles

by Max Javier Jáuregui Rodríguez, Denner Serafim Vieira, Renato Cardoso Nery, Gustavo Sanguino Dias, Ivair Aparecido dos Santos, Renio dos Santos Mendes and Luiz Fernando Cotica

Magnetochemistry 2022, 8(10), 129; https://doi.org/10.3390/magnetochemistry8100129 - 17 Oct 2022

Cited by 1 | Viewed by 1623

Abstract

Particle size distribution carries out a substantial role in the magnetic behavior of nanostructured magnetic systems. In fact, a vast literature on superparamagnetism has been reported, suggesting that the particle size distribution in a system of magnetic nanoparticles (MNPs) corresponds to a lognormal [...] Read more.

Particle size distribution carries out a substantial role in the magnetic behavior of nanostructured magnetic systems. In fact, a vast literature on superparamagnetism has been reported, suggesting that the particle size distribution in a system of magnetic nanoparticles (MNPs) corresponds to a lognormal probability density function, and several works have properly considered their magnetic moments following a similar distribution, as a universal rule. In this manuscript, it is demonstrated that alternative probability distribution functions, such as the gamma and Weibull ones, can be used to obtain useful parameters from the analysis of the magnetization curves, indicating there is no universal model to represent the actual magnetic moment distribution in a system of magnetic nanoparticles. Inspired by this observation, a reliable method to properly identify the actual magnetic moment distribution in a given nanostructured magnetic system is proposed and discussed. Full article

(This article belongs to the Special Issue Advances in Magnetic Nanomaterials and Nanostructures)

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Review

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25 pages, 2641 KiB

Open AccessReview

Recent Approaches in Magnetic Nanoparticle-Based Biosensors of miRNA Detection

by Simge Balaban Hanoglu, Duygu Harmanci, Nursima Ucar, Serap Evran and Suna Timur

Magnetochemistry 2023, 9(1), 23; https://doi.org/10.3390/magnetochemistry9010023 - 06 Jan 2023

Cited by 6 | Viewed by 2332

Abstract

In recent years, magnetic nanoparticles (MNPs) have been widely used in many fields due to their advantageous properties, such as biocompatibility, easy modifiability, and high chemical stability. One of these areas is the detection of cancer. It is essential to use existing biomarkers, [...] Read more.

In recent years, magnetic nanoparticles (MNPs) have been widely used in many fields due to their advantageous properties, such as biocompatibility, easy modifiability, and high chemical stability. One of these areas is the detection of cancer. It is essential to use existing biomarkers, such as microRNAs (miRNAs), for the early diagnosis of this disease. miRNAs are challenging to distinguish and detect in biological samples because they are small, circulating molecules. It is necessary to use more sensitive and feature-rich systems. Thanks to their large surface areas and magnetic moments, MNPs allow easy separation of miRNA at low concentrations from complex samples (urine and blood) and rapid and specific detection in biosensing systems. Here, we discussed the synthesis and characterization methods of MNPs, their stabilization, and MNP-based biosensors in terms of miRNA detection. We considered the challenges and prospects of these biosensor systems in evaluating the development stages, sensitivity, and selectivity. Full article

(This article belongs to the Special Issue Advances in Magnetic Nanomaterials and Nanostructures)

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10 pages, 764 KiB

Open AccessReview

Magnetic Nanomaterials and Nanostructures in Sample Preparation Prior to Liquid Chromatography

by Georgios Antoniou and Victoria Samanidou

Magnetochemistry 2022, 8(3), 29; https://doi.org/10.3390/magnetochemistry8030029 - 03 Mar 2022

Cited by 2 | Viewed by 2415

Abstract

Magnetic nanomaterials and nanostructures compose an innovative subject in sample preparation. Most of them are designed according to the properties of the target analytes on each occasion. The unique characteristics of nanomaterials enhance the proficiency at extracting and enriching due to their selective [...] Read more.

Magnetic nanomaterials and nanostructures compose an innovative subject in sample preparation. Most of them are designed according to the properties of the target analytes on each occasion. The unique characteristics of nanomaterials enhance the proficiency at extracting and enriching due to their selective adsorption ability as well as easy separation and surface modification. Their remarkable properties, such as superparamagnetism, biocompatibility and selectivity have established magnetic materials as very reliable options in sample preparation approaches. In order to comprehend the range of utilization at magnetic materials and nanostructures, this review aims to present the most notable examples in sample preparation prior to liquid chromatography (LC) to the community of analytical chemists. Primarily, the review describes the principles of the techniques in which the magnetic materials are utilized and leaned on. Additionally, there is a diligent report about the novel magnetic techniques and finally a comparison to demonstrate the total point of view. Full article

(This article belongs to the Special Issue Advances in Magnetic Nanomaterials and Nanostructures)

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