Magnetic nanoflowers: a hybrid platform for enzyme immobilization

The use of organic-inorganic hybrid nanoflowers as a support material for enzyme immobilization has gained significant attention in recent years due to their high stability, ease of preparation, and enhanced catalytic activity. However, a major challenge in utilizing these hybrid nanoflowers for enzyme immobilization is the difficulty in handling and separating them due to their low density and high dispersion. To address this issue, magnetic nanoflowers have emerged as a promising alternative enzyme immobilization platform due to their easy separation, structural stability, and ability to enhance catalytic efficiency. This review focuses on different methods for designing magnetic nanoflowers, as well as future research directions. Additionally, it provides examples of enzymes immobilized in the form of magnetic nanoflowers and their applications in environmental remediation, biosensors, and food industries. Finally, the review discusses possible ways to improve the material for enhanced catalytic activity, structural stability, and scalability.

cRGD-Conjugated GdIO Nanoclusters for the Theranostics of Pancreatic Cancer through the Combination of T1-T2 Dual-Modal MRI and DTX Delivery

Clinically, magnetic resonance imaging (MRI) often uses contrast agents (CAs) to improve image contrast, but single-signal MRI CAs are often susceptible to calcification, hemorrhage, and magnetic sensitivity. Herein, iron acetylacetone and gadolinium acetylacetone were used as raw materials to synthesize a T1-T2 dual-mode imaging gadolinium-doped iron oxide (GdIO) nanocluster. Moreover, to endow the nanoclusters with targeting properties and achieve antitumor effects, the cyclic Arg-Gly-Asp (cRGD) peptide and docetaxel (DTX) were attached to the nanocluster surface, and the efficacy of the decorated nanoclusters against pancreatic cancer was evaluated. The final synthesized material cRGD-GdIO-DTX actively targeted αvβ3 on the surface of Panc-1 pancreatic cancer cells. Compared with conventional passive targeting, the enrichment of cRGD-GdIO-DTX in tumor tissues improved, and the diagnostic accuracy was significantly enhanced. Moreover, the acidic tumor microenvironment triggered the release of DTX from cRGD-GdIO-DTX, thus achieving tumor treatment. The inhibition of the proliferation of SW1990 and Panc-1 pancreatic cancer cells by cRGD-GdIO-DTX was much stronger than that by the untargeted GdIO-DTX and free DTX in vitro. In addition, in a human pancreatic cancer xenograft model, cRGD-GdIO-DTX considerably slowed tumor development and demonstrated excellent magnetic resonance enhancement. Our results suggest that cRGD-GdIO-DTX has potential applications for the precise diagnosis and efficient treatment of pancreatic cancer.

Facile synthesis of superparamagnetic nickel-doped iron oxide nanoparticles as high-performance T1 contrast agents for magnetic resonance imaging

Small-sized iron oxide nanoparticles (IONPs) are excellent alternative to clinical gadolinium-based contrast agents (GBCAs) in T1-weighted magnetic resonance imaging (MRI) due to their biosafety. However, the relaxation efficiency and contrast...

Biocompatible Superparamagnetic Europium-Doped Iron Oxide Nanoparticle Clusters as Multifunctional Nanoprobes for Multimodal In Vivo Imaging

Magnetic nanoparticle clusters composed of primary magnetic nanoparticles can not only significantly enhance the magnetic properties of the assembly but also retain the superparamagnetic properties of the individual primary nanoparticle, which is of great significance for promoting the development of multifunctional advanced materials. Herein, water-soluble biocompatible and superparamagnetic europium-doped iron oxide nanoparticle clusters (EuIO NCs) were directly synthesized by a simple one-pot method. The obtained EuIO NCs have excellent water solubility, colloidal stability, and biocompatibility. Europium doping significantly improved the contrast enhancement effect of EuIO NCs in T1-weighted MR imaging. In addition, EuIO NCs can be functionalized by active molecules, and the rhodamine123-functionalized EuIO NCs have long circulation time and excellent fluorescence imaging performance in vivo. This study provides a simple strategy for the design and construction of a novel multifunctional magnetic nanoplatform and provides solutions for the development of multimodal imaging probes and the diagnosis of disease.

Dimpled SiO2@γ-Fe2O3 nanocomposites - fabrication and use for arsenic adsorption in aqueous medium

We report the synthesis of nanocomposites made of silica nanoparticles whose six surface dimples are decorated with magnetic maghemite nanoparticles and their use for detection and recovery of arsenic in aqueous media. Precursor silica nanoparticles have aminated polystyrene chains at the bottom of their dimples and the maghemite nanoparticles are surface functionalized with carboxylic acid groups in two steps: amination with 3-aminopropyltrimethoxysilane, then derivatization with succinic anhydride in the presence of triethylamine. In the end, the colloidal assembly consists of the regioselective grafting of the carboxylic acid-modified iron oxide nanoparticles onto the 6-dimple silica nanoparticles. Several characterization techniques such as transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), dynamic light scattering (DLS) are employed to assess the grafting process and study the influence of the maghemite functional groups on the quality of the composites formed. The resulting magnetic nanocomposites are used for the environmentally benign detection and removal of arsenic from aqueous medium, being readily extracted through means of magnetic separation.

The process of grafting maghemite NFs onto silica dimples.

Controllable synthesis of exceptionally small-sized superparamagnetic magnetite nanoparticles for ultrasensitive MR imaging and angiography

The superparamagnetic iron oxide nanoparticles have broad application prospects in the diagnosis and treatment of cancer.

Libraries of Uniform Magnetic Multicore Nanoparticles with Tunable Dimensions for Biomedical and Photonic Applications

Multicore iron oxide nanoparticles, also known as colloidal nanocrystal clusters, are magnetic materials with diverse applications in biomedicine and photonics. Here, we examine how both of their characteristic dimensional features, the primary particle and sub-micron colloid diameters, influence their magnetic properties and performance in two different applications. The characterization of these basic size-dependent properties is enabled by a synthetic strategy that provides independent control over both the primary nanocrystal and cluster dimensions. Over a wide range of conditions, electron microscopy and X-ray diffraction reveal that the oriented attachment of smaller nanocrystals results in their crystallographic alignment throughout the entire superstructure. We apply a sulfonated polymer with high charge density to prevent cluster aggregation and conjugate molecular dyes to particle surfaces so as to visualize their collection using handheld magnets. These libraries of colloidal clusters, indexed both by primary nanocrystal dimension (d_p) and overall cluster diameter (D_c), form magnetic photonic crystals with relatively weak size-dependent properties. In contrast, their performance as MRI T₂ contrast agents is highly sensitive to cluster diameter, not primary particle size, and is optimized for materials of 50 nm diameter (r₂ = 364 mM^-1 s^-1). These results exemplify the relevance of dimensional control in developing applications for these versatile materials.

One-pot synthesis of water-soluble and biocompatible superparamagnetic gadolinium-doped iron oxide nanoclusters

The synthesis of superparamagnetic nanoclusters is critical for ultra-sensitive magnetic resonance imaging (MRI).

Novel magnetic multicore nanoparticles designed for MPI and other biomedical applications: From synthesis to first in vivo studies

Synthesis of novel magnetic multicore particles (MCP) in the nano range, involves alkaline precipitation of iron(II) chloride in the presence of atmospheric oxygen. This step yields green rust, which is oxidized to obtain magnetic nanoparticles, which probably consist of a magnetite/maghemite mixed-phase. Final growth and annealing at 90°C in the presence of a large excess of carboxymethyl dextran gives MCP very promising magnetic properties for magnetic particle imaging (MPI), an emerging medical imaging modality, and magnetic resonance imaging (MRI). The magnetic nanoparticles are biocompatible and thus potential candidates for future biomedical applications such as cardiovascular imaging, sentinel lymph node mapping in cancer patients, and stem cell tracking. The new MCP that we introduce here have three times higher magnetic particle spectroscopy performance at lower and middle harmonics and five times higher MPS signal strength at higher harmonics compared with Resovist®. In addition, the new MCP have also an improved in vivo MPI performance compared to Resovist®, and we here report the first in vivo MPI investigation of this new generation of magnetic nanoparticles.