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Ferrite spinel's MFe2O4 (M = Co, Fe, Zn, Mn, and Cu) nanoparticles were produced by a co-precipitation method. The X-ray diffraction (XRD) analysis was used to verify phase purity, crystal structure, and average crystallite size of MFe2O4 nanoparticles. All samples have not any phase impurity, which has a spinel structure with crystallite sizes between 7 and 29 nm. The results of far Fourier transform infrared (FTIR) of all samples were revealed in two strong bands about 570 cm−1 and 380 cm−1, which characterize the intrinsic lattice vibrations of octahedral and tetrahedral sites of the spinel structure, respectively. To measure the magnetic properties, a vibrating sample magnetometer (VSM) was used, and the results showed that the manganese nano-ferrite presents the highest saturation magnetization of 55.2 emu/g, while zinc ferrite reveals a low saturation magnetization value of 2.114 emu/g, among different synthesized nano-ferrites. Also, our findings indicated that although both particle size and cation distribution, the magnetic properties are affective on the magnetic properties; however, the role of particle size is more significant. [ABSTRACT FROM AUTHOR]

In the paper, the temperature dependence of magnetic nanoparticle (MNP) paramagnetic chemical shift (paraSHIFT) was studied by magnetic resonance (MR) spectroscopy. Based on it, iron oxide MNPs are considered as MR shifting probes for determining the temperature in liquids. With the increase in measurement temperature of the MNP reagent with MNPs, the decrease of MNP magnetization would make the peak of spectroscopy shift to the higher chemical shift area. The peak shift is related to the magnetic susceptibility of MNPs, which can be determined by MR frequency as a function of temperature and particle size. Experiments on temperature-dependent chemical shifts are performed for MNP samples with different core sizes and the estimated temperature accuracy can achieve 0.1 K. Combined with the contrast effect of magnetic nanoparticles in magnetic resonance imaging at 3 T, this technology can realize temperature imaging. [ABSTRACT FROM AUTHOR]

Cancer cell‐derived extracellular vesicles (EVs) are promising biomarkers for cancer diagnosis and prognosis. However, the lack of rapid and sensitive isolation techniques to obtain EVs from clinical samples at a sufficiently high yield limits their practicability. Chimeric nanocomposites of lactoferrin conjugated 2,2‐bis(methylol)propionic acid dendrimer‐modified magnetic nanoparticles (LF‐bis‐MPA‐MNPs) are fabricated and used for simple and sensitive EV isolation from various biological samples via a combination of electrostatic interaction, physically absorption, and biorecognition between the surfaces of the EVs and the LF‐bis‐MPA‐MNPs. The speed, efficiency, recovery rate, and purity of EV isolation by the LF‐bis‐MPA‐MNPs are superior to those obtained by using established methods. The relative expressions of exosomal microRNAs (miRNAs) from isolated EVs in cancerous cell‐derived exosomes are verified as significantly higher than those from noncancerous ones. Finally, the chimeric nanocomposites are used to assess urinary exosomal miRNAs from urine specimens from 20 prostate cancer (PCa), 10 benign prostatic hyperplasia (BPH), patients and 10 healthy controls. Significant up‐regulation of miR‐21 and miR‐346 and down‐regulation of miR‐23a and miR‐122‐5p occurs in both groups compared to healthy controls. LF‐bis‐MPA‐MNPs provide a rapid, simple, and high yield method for human excreta analysis in clinical applications. [ABSTRACT FROM AUTHOR]

In clinical applications, food, and human metabolism, biological substances including Xanthine (XA), Ascorbic acid (AA), and Uric acid (UA) play essential functions. Finding a technique to identify these compounds without electrochemical interference is critical since they are found in biological fluids and have comparable standard potential values. Herein, Fe3O4@Au core–shell was synthesized and characterized by using EDS analysis, transmission electron microscopy, X-Ray diffraction, and vibrating sample magnetometer. An electrochemical sensor based on Fe3O4@Au/NPs-ionic liquid (IL) (1-n butyl-3methylimidazolium-hexafluoro phosphate) was developed to detect xanthine. Various electrochemical methods including cyclic voltammetry, square wave voltammetry, and chronoamperometry were used to assess the behavior of XA, AA, and UA on the proposed modified electrode. The linear range was calculated to be 0.8–450 µM, and the detection limit of the modified electrode was obtained as 0.4 μM. The developed sensor was also successfully used to simultaneously detect XA in the presence of UA and AA. Finally, the application of the proposed sensor in the measurement of XA was investigated in food samples such as coca-cola, orange juice, and tuna fish using a standard addition method. [ABSTRACT FROM AUTHOR]

The increasing demand for food in the world has made sustainable agriculture practices even more important. Nanotechnology applications in many areas have also been used in sustainable agriculture in recent years for the purposes to improve plant yield, pest control, etc. However, ecotoxicology and environmental safety of nanoparticles must be evaluated before large-scale applications. This study comparatively explores the efficacy and fate of different iron oxide NPs (γ-Fe2O3-maghemite and Fe3O4-magnetite) on barley (Hordeum vulgare L.). Various NP doses (50, 100, and 200 mg/L) were applied to the seeds in hydroponic medium for 3 weeks. Results revealed that γ-Fe2O3 and Fe3O4 NPs significantly improved the germination rate (~37% for γ-Fe2O3; ~63% for Fe3O4), plant biomass, and pigmentation (P < 0.005). Compared to the control, the iron content of tissues gradually raised by the increasing NPs doses revealing their translocation, which is confirmed by VSM analysis as well. The findings suggest that γ-Fe2O3 and Fe3O4 NPs have great potential to improve barley growth. They can be recommended for breeding programs as nanofertilizers. However, special care should be paid before the application due to their unknown effects on other living beings. [ABSTRACT FROM AUTHOR]

A magnetic electrospun nanofibre was prepared and applied to load and release bovine serum albumin (BSA). Fe3O4 magnetic nanoparticles were prepared by chemical co-precipitation of ferric and ferrous salts and coated with polyvinyl alcohol/collagen electrospun nanofibre. Tripolyphosphate (TPP) and glutaraldehyde were used to stabilise nanoparticles within the electrospun nanofibres. It was found from scanning electron microscopy graphs that TPP is more suitable than glutaraldehyde and a network of relatively tall and perfectly uniform fibres with smooth surface can be produced and magnetic nanoparticles in their smallest size are distributed all over the fibres network without any agglomeration. BSA protein was loaded in magnetic nanofibres and its releasing under magnetic field and in the absence of magnetic field was studied using the Bradford assay method. The magnetic nanofibres completely changed the structure and formed pores and cracks under the magnetic field and then released BSA after 3 h, about 12 times higher than its releasing in the absence of magnetic field. [ABSTRACT FROM AUTHOR]

Objective: Sentinel lymph node harvesting is an essential step in the surgical treatment of a growing number of malignancies. Various techniques are available to facilitate this purpose. The present study reports a new laparoscopic technique for lymph node harvesting using magnetic nanoparticles containing a superparamagnetic iron-oxide core and dextran coating. This study assesses the clinical relevance of the prototype and provides input for further technological development on the way to clinical implementation. Methods: A laparoscopic differential magnetometer prototype was built, utilizing a nonlinear detection principle (differential magnetometry) for magnetic identification of lymph nodes. The iron content sensitivity, depth & spatial sensitivity, and angular sensitivity were analyzed to investigate clinical options. Results: The minimum detectable amount of iron was 9.8 μg at a distance of 1 mm. The detection depth was 5, 8, and 10 mm for samples containing 126, 252, and 504 μg iron, respectively. The maximum lateral detection distance was 5, 7, and 8 mm for samples containing 126, 252, and 504 μg iron, respectively. A sample containing 504 μg iron was detectable at all angulations assessed (0°, 30°, 60° and 90°). Conclusion: The laparoscopic differential magnetometer demonstrates promising results for further investigation and development towards laparoscopic lymph node harvesting using magnetic nanoparticles. Significance: The laparoscopic differential magnetometer facilitates a novel method for sentinel lymph node harvesting, which helps to determine prognosis and treatment of cancer patients. [ABSTRACT FROM AUTHOR]

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The novel coronavirus disease (COVID-19) is breaking out and spreading rapidly around the world. There is an urgent need for an accurate and rapid detection method to quickly find infected patients and asymptomatic carriers in order to prevent the spread of the severe acute respiratory syndrome coronavirus [SARS-CoV-2]. In this paper, we designed a test strip which used the principle of double antigen sandwich. Fe3O4 magnetic nanobeads are firstly coupled with specific antibodies, and the S protein of the new coronavirus is used as the coating antigen to capture specific antibodies against the new coronavirus, which is used to detect the virus nucleoprotein of specific antibodies in clinical samples. At the same time, Fe3O4 magnetic nanobeads have unique magnetic properties, which can be used to generate different types of detection signals and simplify the detection process. These results can be judged by color changes and magnetic changes at the test and control lines. Compared with the traditional method, this test strip of Fe3O4 magnetic nanobeads has high sensitivity and can qualitatively detect samples within 15 minutes. The magnetic performance of the magnetic nanobeads can be used to improve the sensitivity of the strip in our further research and product development.

Abstract Cancer cell‐derived extracellular vesicles (EVs) are promising biomarkers for cancer diagnosis and prognosis. However, the lack of rapid and sensitive isolation techniques to obtain EVs from clinical samples at a sufficiently high yield limits their practicability. Chimeric nanocomposites of lactoferrin conjugated 2,2‐bis(methylol)propionic acid dendrimer‐modified magnetic nanoparticles (LF‐bis‐MPA‐MNPs) are fabricated and used for simple and sensitive EV isolation from various biological samples via a combination of electrostatic interaction, physically absorption, and biorecognition between the surfaces of the EVs and the LF‐bis‐MPA‐MNPs. The speed, efficiency, recovery rate, and purity of EV isolation by the LF‐bis‐MPA‐MNPs are superior to those obtained by using established methods. The relative expressions of exosomal microRNAs (miRNAs) from isolated EVs in cancerous cell‐derived exosomes are verified as significantly higher than those from noncancerous ones. Finally, the chimeric nanocomposites are used to assess urinary exosomal miRNAs from urine specimens from 20 prostate cancer (PCa), 10 benign prostatic hyperplasia (BPH), patients and 10 healthy controls. Significant up‐regulation of miR‐21 and miR‐346 and down‐regulation of miR‐23a and miR‐122‐5p occurs in both groups compared to healthy controls. LF‐bis‐MPA‐MNPs provide a rapid, simple, and high yield method for human excreta analysis in clinical applications.

Magnetic nanoparticles (MNP) can generate localized heat in response to an external alternating magnetic field, a unique capability that has enabled a wide range of biomedical applications. Compared with other heating mechanisms such as dielectric heating and ohmic heating, MNP-based magnetic heating offers superior material specificity and minimal damage to the surrounding environment since most biological systems are non-magnetic. This paper presents a first-of-its-kind fully integrated magnetic microheater array based on the ferromagnetic resonance of MNP at Gigahertz (GHz) microwave frequencies. Each microheater pixel consists of a stacked oscillator to actuate MNP with a high magnetic field intensity and an electro-thermal feedback loop for precise temperature regulation. The four-stacked/five-stacked oscillator achieves >19.5/26.5 Vpp measured RF output swing from 1.18 to 2.62 GHz while only occupying a single inductor footprint, which eliminates the need for additional RF power amplifiers for compact pixel size (0.6 mm × 0.7 mm) and high dc-to-RF energy efficiency (45%). The electro-thermal feedback loop senses the local temperature and enables closed-loop temperature regulation by controlling the biasing voltage of the stacked oscillator, achieving a measured maximum/RMS temperature error of 0.53/0.29 °C. In the localized heating demonstration, two PDMS membranes mixed with and without MNP are attached to the microheater array chip, respectively, and their surface temperatures are monitored by an infrared (IR) camera. Only the area above the inductor (∼0.03 mm2) is efficiently heated up to 43 °C for the MNP-PDMS membrane, while the baseline temperature stays <37.8 °C for the PDMS membrane without MNP. [ABSTRACT FROM AUTHOR]

Background: Nanoparticles have been used for biomedical applications, including drug delivery, diagnosis, and imaging based on their unique properties derived from small size and large surface-to-volume ratio. However, concerns regarding unexpected toxicity due to the localization of nanoparticles in the cells are growing. Herein, we quantified the number of cell-internalized nanoparticles and monitored their cellular localization, which are critical factors for biomedical applications of nanoparticles. Methods: This study investigates the intracellular trafficking of silica-coated magnetic nanoparticles containing rhodamine B isothiocyanate dye [MNPs@SiO2(RITC)] in various live single cells, such as HEK293, NIH3T3, and RAW 264.7 cells, using site-specific direct stochastic optical reconstruction microscopy (dSTORM). The time-dependent subdiffraction-limit spatial resolution of the dSTORM method allowed intracellular site-specific quantification and tracking of MNPs@SiO2(RITC). Results: The MNPs@SiO2(RITC) were observed to be highly internalized in RAW 264.7 cells, compared to the HEK293 and NIH3T3 cells undergoing single-particle analysis. In addition, MNPs@SiO2(RITC) were internalized within the nuclei of RAW 264.7 and HEK293 cells but were not detected in the nuclei of NIH3T3 cells. Moreover, because of the treatment of the MNPs@SiO2(RITC), more micronuclei were detected in RAW 264.7 cells than in other cells. Conclusion: The sensitive and quantitative evaluations of MNPs@SiO2(RITC) at specific sites in three different cells using a combination of dSTORM, transcriptomics, and molecular biology were performed. These findings highlight the quantitative differences in the uptake efficiency of MNPs@SiO2(RITC) and ultra-sensitivity, varying according to the cell types as ascertained by subdiffraction-limit super-resolution microscopy. [ABSTRACT FROM AUTHOR]

Two materials were used, like graphene oxide nanosheets (GOn) and ferromagnetic nanoparticles (Fe3O4), to attenuate the electromagnetic (EM) properties in blend hybrid nanocomposites based on styrene-butadiene rubber (SBR) and polyvinylidene difluoride (PVDF) as the matrix. The rationale behind using either a ferroelectric or a ferromagnetic nanofillers as Fe3O4 in combination with intrinsically conducting nanofillers (graphene oxide) at different weight ratios (3.75:1.25; 2.5:2.5 and 1.25:3.75), is to induce both electrical and magnetic dipoles in the hybrid nanocomposite system and characterization to determine the effect of nanofillers hybridization in improving the structural, mechanical, dielectric/electrical, magnetic and thermal properties of a polymer blend (PVDF-SBR) for electromagnetic interference (EMI) shielding application. Due to the synergy between both nanofillers, it was found that Young's modulus of the nanocomposite containing 5 wt% of the hybrid nanofiller was significantly improved (87%), while the strain at yield remained constant due to the low particle content and the rubbery effect of the SBR copolymer. In addition, the degradation temperature of the matrix was shifted from 464 to 472 °C with the addition of 2.5:2.5 of GOn:Fe3O4. Finally, the hybrid reinforcement also had a positive effect on the electrical and magnetic properties of the nanocomposites with an improvement that exceeds 30%. By careful selection of synthetic techniques and understanding/exploiting the unique physics of the polymeric nanocomposites in such materials, novel functional polymer-inorganic nanocomposites can be designed and fabricated for new interests in magneto applications such as superparamagnetism, electromagnetic wave absorption, and electromagnetic interference shielding. This study opens new avenues to design flexible and lightweight electromagnetic interference shielding materials by careful selection of functional nanoparticles. [ABSTRACT FROM AUTHOR]

The magnetic properties of oil constituents appear to be related to their key physical and chemical properties; therefore, the application of new magnetic characterization techniques for oils can make additional contributions to the field. In this study, despite the high dilution of 3d-like ions in crude oil, magnetic susceptibility measurements, recorded at different temperatures and frequencies, and electronic paramagnetic resonance measurements below room temperature were applied to detection of magnetic nanoparticles naturally found in distinctive dehydrated crude oils from the same geological reservoir, but from different oil wells. Electronic paramagnetic resonance measurements probed the presence of Fe3+ ions, with characteristics attributed to magnetite or maghemite (γ-Fe2O3) magnetic nanoparticles in super paramagnetic regime, whilst the presence of a magnetic susceptibility peak, that is visible only at 5000 Hz, has indicated a magnetically blocked regime, via Brownian relaxation, of iron-oxide magnetic nanoparticles. The magnetic susceptibility data showed that it is possible to distinguish the particle size distribution homogeneity and, with the support of the electron paramagnetic resonance technique, the relative fractions of iron-oxide magnetic nanoparticles in crude oils. Thus, these findings show that the magnetic susceptibility technique, supported by electronic paramagnetic resonance spectroscopy, can be applied for the study of magnetic nanoparticles in crude oils and can aid in determining and understanding the fundamental properties of crude oils. [ABSTRACT FROM AUTHOR]

For giant magnetoresistance (GMR) sensors, the in-plane DC detection mode is commonly applied because it offers higher tolerance to the misorientation of the excitation magnetic field as compared to vertical detection mode, and it does not suffer the undesired coupling due to induction by the AC excitation field. However, the quantification result was typically obtained by subtraction method whereby the concentration of the magnetic nanoparticles (MNPs) is determined from the difference between the sensor output voltage signals with and without DC excitation field respectively. While this method is simple, it leads to a high noise level, especially when the concentration of the MNPs is low and the sensor output signal is weak and spiky, resulting in unreliable quantification results. This work aimed at developing a new signal analyzing strategy to obtain quantification results with a higher signal-to-noise ratio (SNR). A linear slope analyzing strategy (slope method) was proposed. The slope of the linear region of the output transfer curve measured with a sweeping excitation field is compared before and after depositing MNPs resulting in $\Delta $ Slope, which indicates the quantity of the MNPs presented on the sensor surface. The slope being the trendline of a transfer curve is more stable and statistically less susceptible to random behavior. Experimental implementation was performed using an MNPs detection platform constructed with a commercial GMR sensor. Results showed that the $\Delta $ Slope increased linearly with the concentration of biotinylated superparamagnetic iron oxide nanoparticles (biotin-IONPs). In comparison with the traditional subtraction method, the SNR was improved from 17.3 dB to 25.3 dB. [ABSTRACT FROM AUTHOR]

A green and stable magnetic Fe3O4 core encapsulated in porous carbon shell was prepared. Then, the surface of as‐synthesized Fe3O4@meso‐C immobilized with activated 4‐aminobenzenesulfonic acid to achieve Fe3O4@C/Ph—SO3H. Structural, physico‐chemical, and magnetic properties of synthesized Fe3O4@C/Ph—SO3H catalyst using various analyses such as FT‐IR spectroscopy, TGA, XRD, SEM, TEM. EDX, and VSM were investigated. Fe3O4@C/Ph—SO3H was used as a stable and recoverable acid catalyst for regioselective three‐component synthesis of tetrazoloquinazolines under mild conditions. This catalyst offers a green protocol of one pot due to having active SO3H groups, reacting in mild conditions with high yield and ability to recover and reuse without significant loss in activity. [ABSTRACT FROM AUTHOR]

In the first phase, PVC was modified with sodium azide through a nucleophilic substitution reaction. Then, the propargyl methacrylate was synthesized from propargyl alcohol and methacryloyl chloride. The copolymerization of propargyl methacrylate and vinyltrimethoxysilane was carried out by free-radical polymerization method in tetrahydrofuran (THF) at 70 °C in with AIBN as the initiator. The magnetic nanoparticle was bonded to vinyltrimethoxysilane units of the copolymer. Finally, the copolymer with propargyl end group bearing the magnetic nanoparticle on its side chain was bonded to PVC-N3 by click reaction. FTIR spectroscopy was used for the characterization. The thermal stability of PVC decreased after the azidation reaction and increased by grafting of magnetic nanoparticles to the copolymer. Vibration sample magnetometer (VSM) measurements revealed that the product reached saturation magnetization (Ms) at 33.7 emu/g, while the pure Fe3O4 nanoparticle showed Ms value of 53.2 emu/g. As the applied frequency increased, the dielectric constant (ε′) and dielectric loss factor (ε″) of the copolymers diminished, while the AC conductivity (σac) increased. [ABSTRACT FROM AUTHOR]

Exfoliated magadiite nanosheets embedded with Fe3O4 were constructed. Advantage was taken of the strong coordination between the silanol groups in magadiite nanosheets and the Gd3+ ion to prepare the final adsorbent, Gd3+-immobilized magnetic magadiite nanosheets. The adsorbent with two-dimensional (2D) morphology offered high surface area and abundant Gd3+ contents for phosphopeptides enrichment, on which Fe3O4 with positive electricity incorporated the magnetic properties. Combining with matrix assisted laser desorption ionization time of flight mass spectrometry (MALDI TOF-MS), the method showed low detection limit (0.05 fmol). The feasibility of using the 2D nanocomposite for phosphopeptides enrichment was demonstrated using mixtures of β-casein and bovine serum albumin (1:5000). The standard deviation of captured phosphopeptides in three repeated experiments were in the range 0.15–0.42 (< 0.5% RSD). Further evaluation revealed that the nanocomposite was capable of enriching phosphopeptides from non-fat milk, human saliva, and serum. [ABSTRACT FROM AUTHOR]

Delivering magnetic nanoparticles (MNPs) into mitochondria provides a facile approach to manipulate cell life because mitochondria play essential roles in cell survival and death. Here we report the use of enzyme‐responsive peptide assemblies to deliver MNPs into mitochondria of live cells. The mitochondria‐targeting peptide (Mito‐Flag), as the substrate of enterokinase (ENTK), assembles with MNPs in solution. The MNPs that are encapsulated by Mito‐Flag peptides selectively accumulate to the mitochondria of cancer cells, rather than normal cells. The mitochondrial localization of MNPs reduces the viability of the cancer cells, but hardly affects the survival of the normal cell. This work demonstrates a new and facile strategy to specifically transport MNPs to the mitochondria in cancer cells for exploring the applications of MNPs as the targeted drug for biomedicine and cancer therapy. [ABSTRACT FROM AUTHOR]

Magnetic nanomaterial has been widely used in water treatment due to its high biocompatibility, good adsorption performance, and easy solid-liquid separation. In this paper,the classification, common form, and functional methods of iron-based magnetic nanocomposites as adsorbents to remove heavy metal ions were summarized. The functional principle of iron-based magnetic nanoparticles and the adsorption mechanism of these materials in adsorption process were discussed. In addition, the unsolved problems, include the agglomeration, oxidation, and unstability of iron-based magnetic nanomaterial applied in wastewater treatment were analyzed. Finally, the functionalization on the iron-based magnetic nanomaterial for the removal of heavy metal ions was prospected, which provides more adequate theoretical basis for heavy metal ions in wastewater treatment.

Background: Protein purification is the most complicated issue in the downstream processes of recombinant protein production; therefore, improved selective purification methods are important. Affinity-based protein purification method using polyhistidine-tag (His-tag) and nickel-nitrilotriacetic acid (Ni-NTA) resins is one of the most common strategies. Magnetic nanoparticles (MNPs) can be used as a beneficial alternative for Ni-NTA resins. However, there is no data on the capability of MNPs for protein purification from inclusion bodies; this issue is studied here. Methods: Recombinant His-tagged proteins of enhanced green fluorescent protein (EGFP)-His and streptokinase (SK)-His were expressed in E. coli BL-21 (DE3) in soluble and inclusion body forms, respectively. MNPs including Fe3O4 magnetic core, SiO2 shell, and Ni2+ on the surface were synthesized by sol-gel and hydrothermal reactions and then characterized by X-ray powder diffraction, vibrating sample magnetometer, and scanning electron microscopy imaging. Both synthesized Fe3O4@NiSiO3 and Fe3O4@NixSiOy MNPs were employed to purify EGEP-His and SK-His under native and denaturing conditions, respectively. The quantity and purity of purified proteins were analyzed by micro-Bradford assay and SDS-PAGE, respectively. Results: Both synthesized MNPs were spherical and well-dispersed with the size ranging from 290 to 415 nm. Synthesized MNPs contained Fe3O4, SiO2 shell, and Ni2+ on their structures with suitable magnetization properties. Using Fe3O4@NiSiO3 and Fe3O4@NixSiOy yielded 192 and 188 µg/mg of SK-His, as compared to 207 and 195 µg/mg of EGFP-His, respectively. Conclusion: MNPs containing magnetic Fe3O4 core, SiO2 shell, and Ni2+on their surface are versatile alternatives for Ni-NTA resins in protein purification for proteins expressed in both soluble and inclusion body forms.

The development of novel magnetic nanoparticles (MNPs) with satisfactory biocompatibility for biomedical applications has been the subject of extensive exploration over the past two decades. In this work, we synthesized superparamagnetic iron oxide MNPs coated with polystyrene sulfonic acid (PSS-MNPs) and with a conventional co-precipitation method. The core size and hydrodynamic diameter of the PSS-MNPs were determined as 8–18 nm and 50–200 nm with a transmission electron microscopy and dynamic light scattering, respectively. The saturation magnetization of the particles was measured as 60 emu g−1 with a superconducting quantum-interference-device magnetometer. The PSS content in the PSS-MNPs was 17% of the entire PSS-MNPs according to thermogravimetric analysis. Fourier-transform infrared spectra were recorded to detect the presence of SO3− groups, which confirmed a successful PSS coating. The structural properties of the PSS-MNPs, including the crystalline lattice, composition and phases, were characterized with an X-ray powder diffractometer and 3D nanometer-scale Raman microspectrometer. MTT assay and Prussian-blue staining showed that, although PSS-MNPs caused no cytotoxicity in both NIH-3T3 mouse fibroblasts and SK-HEP1 human liver-cancer cells up to 1000 μg mL−1, SK-HEP1 cells exhibited significantly greater uptake of PSS-MNPs than NIH-3T3 cells. The low cytotoxicity and high biocompatibility of PSS-MNPs in human cancer cells demonstrated in the present work might have prospective applications for drug delivery.

Microwave heating is one of the prominent treatment procedure that elevates body temperature using microwave energy to damage tumor cells. However, healthy tissues can also absorb microwave energy causing undesired damage. This research study focuses on optimizing the surrounding healthy tissue damage by diffusing magnetic nanoparticles (NPs) in the tumor region. A rectangular liver tissue is modeled using Finite Element Methods (FEM) and then a half-elliptical shaped tumor is incorporated in the model. A coaxial antenna covered with a polytetrafluoroethylene catheter is inserted at the edge of the liver tissue. Then the magnetic NPs are diffused within the tumor region. The performance of microwave heating with and without nanoparticle diffusion is compared using the performance parameters: power dissipation density, temperature distribution, and resultant tissue necrosis. Simulation results show that the heating procedure coupled with ferromagnetic nanoparticle diffusion has approximately 14% less damage to the healthy tissue. The study also shows that 433/915 MHz frequency value provides 3% less damage to the healthy tissue than 2.45 GHz. Analyzing the performance of different nanoparticle we found that the ferromagnetic nanoparticle provides 15% and 5% less damage to the healthy tissue than gold and manganese iron oxide NPs respectively. The obtained result was also verified for kidney, breast, and lung tumor ablations to confirm the findings.

In this study, Fe3O4@SiO2-PAF-SO3H nanocomposite was successfully fabricated by immobilization of sulfonic acid groups on the surface of poly(anilin-formaldehyde)-supported on magnetic Fe3O4@SiO2 nanoparticles through layer-by-layer assembly. Fe3O4@SiO2-PAF-SO3H composite nanostructure has been fully characterized using various techniques including the Fourier-transform infrared spectroscopy (FT-IR), X-ray powder diffraction patterns (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and vibrating sample magnetometry (VSM). The one-pot synthesis of mono and bis 1,4-dihydropyridine derivatives, as pharmaceutically interesting compounds, have been achieved in high yields via three-component and pseudo five component condensation of an aromatic aldehyde, ammonium acetate and ethyl acetoacetate in the presence of Fe3O4@SiO2-PAF-SO3H as a novel retrievable hybrid nanocatalyst under solvent-free conditions. This protocol has advantages in terms of short reaction time, solvent-free condition, high yield and purity, easy work-up and eco-friendly process as well as recyclability of the nanocatalyst (at least 6 times) with no decrease in catalytic activity.

The conversion of flavonoid glycosides and their analogs to their lipophilic ester derivatives was developed by nanobiocatalysts from immobilizing Thermomyces lanuginosus lipase (TLL) on polydopamine-functionalized magnetic Fe3O4 nanoparticles (Fe3O4-PDA-TLL). The behavior investigation revealed that Fe3O4-PDA-TLL exhibits a preference for long chain length fatty acids (i.e., C10 to C14) with higher reaction rates of 12.6–13.9 mM/h. Regarding the substrate specificity, Fe3O4-PDA-TLL showed good substrate spectrum and favorably functionalized the primary OH groups, suggesting that the steric hindrances impeded the secondary or phenolic hydroxyl groups of substrates into the bonding site of the active region of TLL to afford the product.

The recent decade has witnessed a remarkable surge in the field of nanoparticles, from their synthesis, characterization, and functionalization to diverse applications. At the nanoscale, these particles exhibit distinct physicochemical properties compared to their bulk counterparts, enabling a multitude of applications spanning energy, catalysis, environmental remediation, biomedicine, and beyond. This review focuses on specific nanoparticle categories, including magnetic, gold, silver, and quantum dots (QDs), as well as hybrid variants, specifically tailored for biomedical applications. A comprehensive review and comparison of prevalent chemical, physical, and biological synthesis methods are presented. To enhance biocompatibility and colloidal stability, and facilitate surface modification and cargo/agent loading, nanoparticle surfaces are coated with different synthetic polymers and very recently, cell membrane coatings. The utilization of polymer- or cell membrane-coated nanoparticles opens a wide variety of biomedical applications such as magnetic resonance imaging (MRI), hyperthermia, photothermia, sample enrichment, bioassays, drug delivery, etc. With this review, the goal is to provide a comprehensive toolbox of insights into polymer or cell membrane-coated nanoparticles and their biomedical applications, while also addressing the challenges involved in translating such nanoparticles from laboratory benchtops to in vitro and in vivo applications. Furthermore, perspectives on future trends and developments in this rapidly evolving domain are provided., (© 2024 Wiley‐VCH GmbH.)

Adeno-associated viruses (AAVs) are intensively explored for gene therapies in general and have found promising applications for treating retina diseases. However, controlling the specificity (tropism) and delivery of AAVs to selected layers, cell types, and areas of the retina is a major challenge to further develop retinal gene therapies. Magnetic nanoparticles (MNPs) provide effective delivery platforms to magnetically guide therapeutics to target cells. Yet, how MNPs can deliver AAVs to transfect particular retina layers and cells remains elusive. Here, it is demonstrated that MNPs can be used to transport different AAVs through the retina and to modulate the selective transduction of specific retinal layers or photoreceptor cells in ex vivo porcine explants and whole eyes. Thereby, transduction is triggered by bringing the viruses in close proximity to the target cell layer and by controlling their interaction time. It is shown that this magnetically guided approach to transport AAVs to selected areas and layers of the retina does not require the cell-specific optimization of the AAV tropism. It is anticipated that the new approach to control the delivery of AAVs and to selectively transduce cellular systems can be applied to many other tissues or organs to selectively deliver genes of interest., (© 2024 The Author(s). Advanced Healthcare Materials published by Wiley‐VCH GmbH.)

Magnetic particles (MPs), with magnetite (Fe 3 O 4 ) and maghemite (γ-Fe 2 O 3 ) as the most abundant species, are ubiquitously present in the natural environment. MPs are among the most applied engineered particles and can be produced incidentally by various human activities. Identification of the sources of MPs is crucial for their risk assessment and regulation, which, however, is still an unsolved problem. Here, we report a novel approach, hierarchical classification-aided stable isotopic fingerprinting, to address this problem. We found that naturally occurring, incidental, and engineered MPs have distinct Fe and O isotopic fingerprints due to significant Fe/O isotope fractionation during their generation processes, which enables the establishment of an Fe-O isotopic library covering complex sources. Furthermore, we developed a three-level machine learning model that not only can distinguish the sources of MPs with a high precision (94.3%) but also can identify the multiple species (Fe 3 O 4 or γ-Fe 2 O 3 ) and synthetic routes of engineered MPs with a precision of 81.6%. This work represents the first reliable strategy for the precise source tracing of particles with multiple species and complex sources.

The CRISPR-Cas9 technology has the potential to revolutionize the treatment of various diseases, including Rett syndrome, by enabling the correction of genes or mutations in human patient cells. However, several challenges need to be addressed before its widespread clinical application. These challenges include the low delivery efficiencies to target cells, the actual efficiency of the genome-editing process, and the precision with which the CRISPR-Cas system operates. Herein, the study presents a Magnetic Nanoparticle-Assisted Genome Editing (MAGE) platform, which significantly improves the transfection efficiency, biocompatibility, and genome-editing accuracy of CRISPR-Cas9 technology. To demonstrate the feasibility of the developed technology, MAGE is applied to correct the mutated MeCP2 gene in induced pluripotent stem cell-derived neural progenitor cells (iPSC-NPCs) from a Rett syndrome patient. By combining magnetofection and magnetic-activated cell sorting, MAGE achieves higher multi-plasmid delivery (99.3%) and repairing efficiencies (42.95%) with significantly shorter incubation times than conventional transfection agents without size limitations on plasmids. The repaired iPSC-NPCs showed similar characteristics as wild-type neurons when they differentiated into neurons, further validating MAGE and its potential for future clinical applications. In short, the developed nanobio-combined CRISPR-Cas9 technology offers the potential for various clinical applications, particularly in stem cell therapies targeting different genetic diseases., (© 2024 The Authors. Advanced Science published by Wiley‐VCH GmbH.)

Nanocomposite hydrogels are highly porous colloidal structures with a high adsorption capacity, making them promising materials for wastewater treatment. In particular, magnetic nanoparticle (MNP) incorporated hydrogels are an excellent adsorbent for aquatic pollutants. An added advantage is that, with the application of an external magnetic field, magnetic hydrogels can be collected back from the wastewater system. However, magnetic hydrogels are quite brittle and structurally unstable under compact conditions such as in fixed-bed adsorption columns. To address this issue, this study demonstrates a unique hydrogel composite bead structure, providing a good adsorption capacity and superior compressive stress tolerance due to the presence of hollow cores within the beads. The gel beads contain alginate polymer as the matrix and MNP-decorated cellulose nanofibres (CNF) as the reinforcing agent. The MNPs within the gel provide active adsorption functionality, while CNF provide a good stress transfer phenomenon when the beads are under compressive stress. Their adsorption performance is evaluated in a red mud solution for pollutant adsorption. Composite gel beads have shown high performance in adsorbing metal (aluminium, potassium, selenium, sodium, and vanadium) and non-metal (sulphur) contaminations. This novel hybrid hydrogel could be a promising alternative to the conventionally used toxic adsorbent, providing environmentally friendly operational benefits.

MnFe2O4 ferrite nanoparticle was synthesized via the sol–gel method, and structural, morphology and magnetic characteristics were investigated. X-ray diffraction analysis showed that the synthesized sample was in a single phase with a spinel-ferrite-like structure (space group Fd-3m). The scanning electron microscopy displayed homogenous spherical grains with an agglomeration of the particles. The chemical composition determined by energy-dispersive spectroscopy shows the absence of any impurities. To understand the role of magnetic interaction in MnFe2O4 spinel ferrites, the structural and magnetic properties of MnFe2O4 have been explored theoretically. Based on the first-principles methods via density functional theory and Monte Carlo simulations, the magnetic hysteresis cycle has been plotted. Using the generalized gradient and GGA-PBE approximation in the full-potential linearized augmented plane wave (FP-LAPW) method, the exchange coupling interactions between magnetic elements and local magnetic moment were evaluated. Furthermore, the theoretical magnetic properties of MnFe2O4 were found to match the experimental ones. They both revealed that MnFe2O4 is a soft ferromagnetic material. The theoretical curve of magnetization versus temperature indicates that the transition occurred at Tc = 580.0 K. This was also in good agreement with the experimental Curie temperature.

To solve the problem of ice condensation and adhesion, it is urgent to develop new anti-icing and deicing technologies. This study presented the development of a highly efficient photothermal-enhanced superhydrophobic PDMS/Ni@Ti 3 C 2 T x composite film ( m -NMPA) fabricated cost-effectively and straightforwardly. This film was fabricated utilizing PDMS as a hydrophobic agent, adhesive, and surface protector, while Ni@Ti 3 C 2 T x as a magnetic photothermal filler innovatively. Through a simple spraying method, the filler is guided by a strong magnetic field to self-assemble into an eyelash-like microstructure array. The unique structure not only imparts superhydrophobic properties to the surface but also constructs an efficient "light-capturing" architecture. Remarkably, the m -NMPA film demonstrates outstanding superhydrophobic passive anti-icing and efficient photothermal active deicing performance without the use of fluorinated chemicals. The micro-/nanostructure of the film forms a gas layer, significantly delaying the freezing time of water. Particularly under extreme cold conditions (-30 °C), the freezing time is extended by a factor of 7.3 compared to the bare substrate. Furthermore, under sunlight exposure, surface droplets do not freeze. The excellent photothermal performance is attributed to the firm anchoring of nickel particles on the MXene surface, facilitating effective "point-to-face" photothermal synergy. The eyelash-like microarray structure enhances light-capturing capability, resulting in a high light absorption rate of 98%. Furthermore, the microstructure aids in maintaining heat at the uppermost layer of the surface, maximizing the utilization of thermal energy for ice melting and frost thawing. Under solar irradiation, the m -NMPA film can rapidly melt approximately a 4 mm thick ice layer within 558 s and expel the melted water promptly, reducing the risk of secondary icing. Additionally, the ice adhesion force on the surface of the m -NMPA film is remarkably low, with an adhesion strength of approximately 4.7 kPa for a 1 × 1 cm 2 ice column. After undergoing rigorous durability tests, including xenon lamp weathering test, pressure resistance test, repeated adhesive tape testing, xenon lamp irradiation, water drop impact testing, and repeated brushing with hydrochloric acid and particles, the film's surface structure and superhydrophobic performance have remained exceptional. The photothermal superhydrophobic passive anti-icing and active deicing technology in this work rely on sustainable solar energy for efficient heat generation. It presents broad prospects for practical applications with advantages such as simple processing method, environmental friendliness, outstanding anti-icing effects, and exceptional durability.

Plasminogen activators, such as recombinant tissue-type plasminogen activators (rtPAs), while effective in treating thromboembolic diseases, often induce hemorrhagic complications due to non-specific enzyme activities in the systemic circulation. This study evaluated the targeting efficiency, efficacy, biodistribution, and potential toxicity of a rtPA covalently attached to chitosan-coated magnetic nanoparticles (chitosan-MNP-rtPA). The thrombolytic activity of a chitosan-MNP-rtPA was preserved by protection from an endogenous plasminogen activator inhibitor-1 (PAI-1) in whole blood and after circulation in vivo, as examined by thromboelastometry. Single-photon emission computed tomography (SPECT) demonstrated real-time retention of a 99m Tc-MNP-rtPA induced by magnet application in a rat embolic model; an 80% reduction in rtPA dosage for a chitosan-MNP-rtPA with magnetic guidance was shown to restore blood flow. After treatment, iron deposition was observed in the reticuloendothelial systems, with portal edema and neutrophil infiltration in the liver at a ten-fold higher dose but not the regular dose. Nevertheless, no liver or renal toxicity was observed at this higher dose. In conclusion, the liver may still be the major deposit site of rtPA nanocomposites after targeted delivery; chitosan-coated MNPs are potentially amenable to target therapeutics with parenteral administration.

We present a microfluidic chip for protein labeling in the human serum-based matrix. Serum is a complex sample matrix that contains a variety of proteins, and a matrix is used in many clinical tests. In this study, the device performance was tested using commercial serum samples from healthy donors spiked with the following target proteins: cellular fibronectin (c-Fn) and matrix metallopeptidase 9 (MMP9). The microfluidic molds were fabricated using micro milling on acrylic and using stereolithography (SLA) three-dimensional (3D) printing for an alternative method and comparison. A simple quality control was performed for both fabrication mold methods to inspect the channel height of the chip that plays a critical role in the labeling process. The fabricated microfluidic chip shows a good reproducibility and repeatability of the performance for the optimized channel height of 150 µm. The spiked proteins of c-Fn and MMP9 in the human serum-based matrix, were successfully labeled by the functionalized magnetic nanoparticles (MNPs). The biomarker labeling occurring in the serum was compared using a simple matrix sample: phosphate buffer. The measured signals obtained by using a magnetoresistive (MR) biochip platform showed that the labeling using the proposed microfluidic chip is in good agreement for both matrixes, i.e., the analytical performance (sensitivity) obtained with the serum, near the relevant cutoff values, is within the uncertainty of the measurements obtained with a simple and more controlled matrix: phosphate buffer. This finding is promising for stroke patient stratification where these biomarkers are found at high concentrations in the serum.

Soil enzymes, such as invertase, urease, acidic phosphatase and catalase, play critical roles in soil biochemical reactions and are involved in soil fertility. However, it remains a great challenge to efficiently concentrate soil enzymes and sensitively assess enzyme activity. In this study, we synthesized phenylboronic acid-functionalized magnetic nanoparticles to rapidly capture soil enzymes for sensitive soil enzyme assays. The iron oxide magnetic nanoparticles (MNPs) were firstly prepared by the co-precipitation method and then functionalized by (3-aminopropyl)triethoxysilane, polyethyleneimine and phenylboric acid in turn, obtaining the final nanoparticles (MNPPBA). Protein-capturing assays showed that the functionalized MNPs had a much higher protein-capturing capacity than the naked MNPs (56% versus 6%). Moreover, MNPPBA almost thoroughly captured the tested enzymes, i.e., urease, invertase, and alkaline phosphatase, from enzyme solutions. Based on MNPPBA, a soil enzyme assay method was developed by integration of enzyme capture, magnetic separation and trace enzyme analysis. The method was successfully applied in determining trace enzyme activity in rhizosphere soil. This study provides a strategy to sensitively determine soil enzyme activity for mechanistic investigation of soil fertility and plant–microbiome interaction.

A straightforward and facile synthesis of cellulosic-carbon-shielded palladium–magnetic nanoparticle hybrid material (Pd-MNP@SCB) is presented here. Naturally abundant cellulose was isolated from waste sugarcane bagasse via simple base hydrolysis method and employed. Large surface area and porosity are crucial factors which can enhance the efficiency of a material in catalysis as well as energy storage application and the same was tried to achieve here using the cellulosic-carbon as a support. The prepared hybrid material was initially screened for its catalytic activity in Suzuki–Miyaura cross-coupling followed by its utilization in energy storage application. Pd-MNP@SCB could catalyze the cross-coupling reaction very efficiently with excellent functional group tolerance and good recyclability. The electrochemical performance was explored for Pd-MNP@SCB assembled in a two-electrode cell configuration. The maximum capacitance was found to be 121.74 F/g at a current density of 0.07 A/g with an excellent cycling stability of 97.69% over 3000 cycles. [ABSTRACT FROM AUTHOR]

The presence of sulfate groups in agar compromises the agar quality by affecting the crosslinking during gelling process. Some arylsulfatases can catalyze the hydrolysis of sulfate bonds in agar to improve the agar quality. Immobilized arylsulfatases prove beneficial advantages for their industrial applications. Here, a previously characterized mutant arylsulfatase K253H/H260L was immobilized on the synthesized magnetic Fe3O4 nanoparticles after functionalization by tannic acid (MNPs@TA). The surface properties and molecular structures of the immobilized arylsulfatase (MNPs@TA@ARS) were examined by scanning electron microscopy and Fourier transform infrared spectroscopy. Enzymatic characterization showed that MNPs@TA@ARS exhibited shifted optimal temperature and pH with deviated apparent Km and Vmax compared to its free counterpart. The immobilized arylsulfatase demonstrated improved thermal and pH stability and enhanced storage stability with modest reusability. In addition, MNPs@TA@ARS displayed enhanced tolerance to various inhibitors and detergents. The utilization of the immobilized arylsulfatase for agar desulfation brought the treated agar with improved quality. [ABSTRACT FROM AUTHOR]

In recent years, magnetophoresis of magnetic nanoparticles (MNPs) has been emerged as one of the most appealing separation technologies in water treatment and biomedical applications. Magnetophoresis of MNPs can be further divided into two classes: high gradient magnetic separation (HGMS) and low gradient magnetic separation (LGMS). In the past decades, LGMS has been revealed to outperform HGMS in several aspects, such as simplicity, energy-saving and low cost. Therefore, in this work, we intend to extend the LGMS to continuous flow operation mode so that the wide implementation of this technology in the industry can be facilitated. Here, a mathematical model was developed to depict the kinetic of continuous flow LGMS (CF-LGMS) process by using poly(diallyldimethylammonium chloride) (PDDA)-coated MNPs with 64.4 nm core diameter and 107.4 nm hydrodynamic diameter (saturation magnetization = 71 Am2/kg) as the particle model system. By using this model, the effect of several critical design parameters on the separation efficiency was evaluated. According to our simulation result, it can be revealed that the separation efficiency of CF-LGMS is improved by performing the separation under low flowrate of MNP solution (~ 98.04% separation efficiency under low flow velocities of 5 and 10 mm/s) and high particle concentration (~ 98.04% separation efficiency under high particle concentration of 100, 500 and 1000 mg/L). Nevertheless, the magnetic field that is vertically symmetry will impose higher separation efficiency on the CF-LGMS, as compared to its asymmetry counterparts. Lastly, we performed a cost analysis on the batchwise (RM 22.19/h) as well as continuous flow magnetic separators (RM 37.47/h) and found that LGMS conducted under continuous flow mode is more economically friendly to be implemented in the real-time industry. [ABSTRACT FROM AUTHOR]

In the present study synthesis of magnetic nanoparticle (MNPs), impregnated walnut shell powder (MNPs-WSP) were carried out using the co-precipitation method and used for the solid-phase extraction of Cd(II) from environmental water samples. Impregnated walnut shell powder (MNPs- WSP) was characterized by using Fourier transform infrared spectroscopy for functional group, scanning electron microscopy for surface morphology, energy dispersive X-ray analysis for elemental analysis, X-ray diffraction for crystallinity and SAA for surface area, pore volume and pore size. For quantitative percent recovery various analytical parameters like solution pH, sample volume, vertex time, temperature and initial metal ion concentration were optimized. Analytical parameters like limit of detection, limit of quantification and enhancement factor were also calculated under optimized experimental conditions. The kinetic data shows that the adsorption of Cd(II) on MNPs and MNPs-WSP follows pseudo-second-order kinetics. Values of ΔH°, ΔS° and ΔG° show that these adsorption processes are endothermic and feasible in nature. For equilibrium studies different isotherms like Langmuir and Freundlich, adsorption isotherms were applied. The method was successfully applied to environmental water samples like tap water, underground water, dam water and wastewater with satisfied recovery results. [ABSTRACT FROM AUTHOR]

Owing to their inherent features like smaller size and higher surface area exposed to reactants, iron oxide nanoparticles have gained enormous interest and are extensively used as magnetically recyclable catalysts for various organic reactions. Herein, we report highly hydrophilic, non-aggregated, and strongly positively charged (ζ potential: + 45.7 mV) ultra-small cerium cations/complexes- stabilized maghemite nanoparticles in water as an efficient and reusable nanoscaled catalyst for the nucleophilic addition reaction of various amines with α,β-unsaturated carbonyl compounds to give corresponding β-amino derivatives under ultrasonic irradiation. The developed protocol provides several merits such as high product yields, mild reaction conditions, reusable catalyst and easy workup. [ABSTRACT FROM AUTHOR]