Fabrication of bifunctional core-shell Fe3O4 particles coated with ultrathin phosphor layer

Heavy Metal Adsorption Using Magnetic Nanoparticles for Water Purification: A Critical Review

Research on contamination of groundwater and drinking water is of major importance. Due to the rapid and significant progress in the last decade in nanotechnology and its potential applications to water purification, such as adsorption of heavy metal ion from contaminated water, a wide number of articles have been published. An evaluating frame of the main findings of recent research on heavy metal removal using magnetic nanoparticles, with emphasis on water quality and method applicability, is presented. A large number of articles have been studied with a focus on the synthesis and characterization procedures for bare and modified magnetic nanoparticles as well as on their adsorption capacity and the corresponding desorption process of the methods are presented. The present review analysis shows that the experimental procedures demonstrate high adsorption capacity for pollutants from aquatic solutions. Moreover, reuse of the employed nanoparticles up to five times leads to an efficiency up to 90%. We must mention also that in some rare occasions, nanoparticles have been reused up to 22 times.

Synthesis and Characterization of a Fe3O4@PNIPAM-Chitosan Nanocomposite and Its Potential Application in Vincristine Delivery

In this research, we conducted a systematic evaluation of the synthesis parameters of a multi-responsive core-shell nanocomposite (Fe₃O₄ nanoparticles coated by poly(N-isopropylacrylamide) (PNIPAM) in the presence of chitosan (CS) (Fe₃O₄@PNIPAM-CS). Scanning electron microscopy (SEM) was used to follow the size and morphology of the nanocomposite. The functionalization and the coating of Fe₃O₄ nanoparticles (Nps) were evaluated by the ζ-potential evolution and Fourier Transform infrared spectroscopy (FTIR). The nanocomposite exhibited a collapsed structure when the temperature was driven above the lower critical solution temperature (LCST), determined by dynamic light scattering (DLS). The LCST was successfully shifted from 33 to 39 °C, which opens the possibility of using it in physiological systems. A magnetometry test was performed to confirm the superparamagnetic behavior at room temperature. The obtained systems allow the possibility to control specific properties, such as particle size and morphology. Finally, we performed vincristine sulfate loading and release tests. Mathematical analysis reveals a two-stage structural-relaxation release model beyond the LCST. In contrast, a temperature of 25 °C promotes the diffusional release model. As a result, a more in-depth comprehension of the release kinetics was achieved. The synthesis and study of a magnetic core-shell nanoplatform offer a smart material as an alternative targeted release therapy due to its thermomagnetic properties.

Sn2+ Doping: A Strategy for Tuning of Fe3O4 Nanoparticles Magnetization Dipping Temperature/Amplitude, Irreversibility, and Curie Point

Doped magnetite (Sn_xFe_3-2/3xO₄) nanoparticles (NPs) (12-50 nm) with different amount of Sn²⁺ ions (x) were synthesized using co-precipitation method. Sn²⁺ doping reduces the anticipated oxidation of Fe₃O₄ NPs to maghemite (γ-Fe₂O₃), making them attractive in several magnetic applications. Detailed characterizations during heating-cooling cycles revealed the possibility of tuning the unusual observed magnetization dipping temperature/amplitude, irreversibility, and Curie point of these NPs. We attribute this dip to the chemical reduction of γ-Fe₂O₃ at the NPs surfaces. Along with an increase in the dipping temperature, we found that doping with Sn²⁺ reduces the dipping amplitude, until it approximately disappears when x = 0.150. Based on the core-shell structure of these NPs, a phenomenological expression that combines both modified Bloch law (M = M₀[1 - γ(T/T_C)]^β) and a modified Curie-Weiss law (M = - α[1/(T - T_C)^δ]) is developed in order to explain the observed M-T behavior at different applied external magnetic fields and for different Sn²⁺ concentrations. By applying high enough magnetic field, the value of the parameters γ and δ ≈ 1 which are the same in modified Bloch and Curie-Weiss laws. They do not change with the magnetic field and depend only on the material structure and size. The power β for high magnetic field was 2.6 which is as expected for this size of nanoparticles with the core dominated magnetization. However, the β value fluctuates between 3 and 10 for small magnetic fields indicating an extra magnetic contribution from the shell structure presented by Curie-Weiss term. The parameter (α) has a very small value and it turns to negative values for high magnetic fields.

Toxicity and T₂-Weighted Magnetic Resonance Imaging Potentials of Holmium Oxide Nanoparticles

In recent years, paramagnetic nanoparticles (NPs) have been widely used for magnetic resonance imaging (MRI). This paper reports the fabrication and toxicity evaluation of polyethylene glycol (PEG)-functionalized holmium oxide (Ho₂O₃) NPs for potential T₂-weighted MRI applications. Various characterization techniques were used to examine the morphology, structure and chemical properties of the prepared PEG-Ho₂O₃ NPs. MRI relaxivity measurements revealed that PEG-Ho₂O₃ NPs could generate a strong negative contrast in T₂-weighted MRI. The pilot cytotoxicity experiments showed that the prepared PEG-Ho₂O₃ NPs are biocompatible at concentrations less than 16 μg/mL. Overall, the prepared PEG-Ho₂O₃ NPs have potential applications for T₂-weighted MRI imaging.

Eu, Gd-Codoped Yttria Nanoprobes for Optical and T₁-Weighted Magnetic Resonance Imaging

Nanoprobes with multimodal functionality have attracted significant interest recently because of their potential applications in nanomedicine. This paper reports the successful development of lanthanide-doped Y₂O₃ nanoprobes for potential applications in optical and magnetic resonance (MR) imaging. The morphology, structural, and optical properties of these nanoprobes were characterized by transmission electron microscope (TEM), field emission scanning electron microscope (FESEM), X-ray diffraction (XRD), energy-dispersive X-ray (EDX), and photoluminescence (PL). The cytotoxicity test showed that the prepared lanthanide-doped Y₂O₃ nanoprobes have good biocompatibility. The obvious contrast enhancement in the T₁-weighted MR images suggested that these nanoprobes can be used as a positive contrast agent in MRI. In addition, the clear fluorescence images of the L-929 cells incubated with the nanoprobes highlight their potential for optical imaging. Overall, these results suggest that prepared lanthanide-doped Y₂O₃ nanoprobes can be used for simultaneous optical and MR imaging.

Paclitaxel loaded magnetic nanocomposites with folate modified chitosan/carboxymethyl surface; a vehicle for imaging and targeted drug delivery

In this study, Paclitaxel (PTX) containing, bovine serum albumin (BSA) nanoparticles were fabricated via a simple approach. Folic acid (FA) was conjugated to chitosan (CS)/carboxymethyl cellulose (CMC) through an esterification reaction to produce BSA-CS-FA or BSA-CMC-FA conjugates. NiFe₂O₄ noncore (NFs) and PTX were loaded through a heat treatment and by a diffusion process. NFs-BSA-CS and NFs-BSA-CMC-FA with size of about 80nm, showed superior transversal R₂ relaxation rate of 349 (mM)^-1s^-1 along with folate receptor-targeted and magnetically directed functions. NFs-BSA-CS-FA or NFs-BSA-CS-FA were found stable and biocompatible. Application of an external magnetic field effectively enhanced the PTX release from PTX-NFs-BSA-CS-FA or PTX-NFs-BSA-CS-FA and hence tumor inhibition rate. This study validate that NFs-BSA-CS-FA or NFs-BSA-CMC-FA and PTX-NFs-BSA-CS-FA or PTX-NFs-BSA-CS-FA are suitable systems for tumor diagnosis and therapy.

Microwave-assisted green synthesis of superparamagnetic nanoparticles using fruit peel extracts: surface engineering, T 2 relaxometry, and photodynamic treatment potential

Superparamagnetic iron oxide nanoparticles (SPIONs) have the potential to be used as multimodal imaging and cancer therapy agents due to their excellent magnetism and ability to generate reactive oxygen species when exposed to light. We report the synthesis of highly biocompatible SPIONs through a facile green approach using fruit peel extracts as the biogenic reductant. This green synthesis protocol involves the stabilization of SPIONs through coordination of different phytochemicals. The SPIONs were functionalized with polyethylene glycol (PEG)-6000 and succinic acid and were extensively characterized by X-ray diffraction analysis, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, atomic force microscopy, Rutherford backscattering spectrometry, diffused reflectance spectroscopy, fluorescence emission, Fourier-transform infrared spectroscopy, ultraviolet-visible spectroscopy, and magnetization analysis. The developed SPIONs were found to be stable, almost spherical with a size range of 17-25 nm. They exhibited excellent water dispersibility, colloidal stability, and relatively high R 2 relaxivity (225 mM(-1) s(-1)). Cell viability assay data revealed that PEGylation or carboxylation appears to significantly shield the surface of the particles but does not lead to improved cytocompatibility. A highly significant increase of reactive oxygen species in light-exposed samples was found to play an important role in the photokilling of human cervical epithelial malignant carcinoma (HeLa) cells. The bio-SPIONs developed are highly favorable for various biomedical applications without risking interference from potentially toxic reagents.

Multicolor nanoprobes based on silica-coated gadolinium oxide nanoparticles with highly reduced toxicity

Multicolor core-shell nanoprobes were developed for molecular imaging of living cells using optical and MRI technique.

Ultrafine PEG-capped gadolinia nanoparticles: cytotoxicity and potential biomedical applications for MRI and luminescent imaging

Ultrafine PEG-capped gadolinium oxide NPs doped with erbium ions, which could serve as a dual-imaging agent for MRI/optical imaging were synthesized using a simple, green, and quick method.