Magnetic core-bilayer shell nanoparticle: A novel vehicle for entrapmentof poorly water-soluble drugs

Anionic polymer-coated magnetic nanocomposites for immobilization with palladium nanoparticles as catalysts for the reduction of 4-nitrophenol

This study focuses on the synthesis of magnetite nanoparticles (MNP) coated with poly(poly(ethylene glycol) methacrylate) (PPEGMA) and/or poly(acrylic acid) (PAA) to anchor palladium nanoparticles (Pd) for their application as recyclable catalysts in the reduction of 4-nitrophenol (4NP). It was hypothesized that the abundance of oxygen atoms in PPEGMA enabled coordination with the Pd and provided good water dispersibility of the nanocomposites, while anionic PAA stabilized Pd and reduced the catalyst aggregation through electrostatic repulsion. Three different polymer coatings on MNP (PAA, PPEGMA, and PAA-co-PPEGMA polymers) were investigated to assess their influence on both the catalytic activity and reusability of the catalysts. Transmission electron microscopy (TEM) analysis indicated the distribution of spherical Pd nanoparticles (3-5 nm in diameter) and MNP (9-12 nm in diameter). Photocorrelation spectroscopy (PCS) revealed an average hydrodynamic size of the catalysts ranging from 540 to 875 nm in diameter, with a negative charge on their surface. The Pd content of the catalysts ranged from 4.30 to 6.33% w/w. The nanocomposites coated with PAA-co-PPEGMA polymers exhibited more favorable catalytic activity in the 4NP reduction than those coated with PAA or PPEGMA homopolymers. Interestingly, those containing PAA (e.g., PAA and PAA-co-PPEGMA polymers) exhibited good reusability for the 4NP reduction with a slight decrease in their catalytic performance after 26 cycles. This indicates the important role of carboxyl groups in PAA in maintaining high tolerance after multiple uses.

Hafnium Oxide-Based Nanoplatform for Combined Chemoradiotherapy

Recently, the combined therapy has become one of the main approaches in cancer treatment. Combining different approaches may provide a significant outcome by triggering several death mechanisms or causing increased damage of tumor cells without hurting healthy ones. The supramolecular nanoplatform based on a high-Z metal reported here is a suitable system for the targeted delivery of chemotherapeutic compounds, imaging, and an enhanced radiotherapy outcome. HfO₂ nanoparticles coated with oleic acid and a monomethoxypoly(ethylene glycol)-poly(ε-caprolactone) copolymer shell (nanoplatform) are able to accumulate inside cancer cells and release doxorubicin (DOX) under specific conditions. Neither uncoated nor coated nanoparticles show any cytotoxicity in vitro. DOX loaded onto a nanoplatform demonstrates a lower IC₅₀ value than pure DOX. X-ray irradiation of cancer cells loaded with a nanoplatform shows a higher death rate than that for cells without nanoparticles. These results provide an important foundation for the development of complex nanoscale systems for combined cancer treatment.

Self-Assembly of Magnetic Nanoparticles in Ferrofluids on Different Templates Investigated by Neutron Reflectometry

In this article we review the process by which magnetite nanoparticles self-assemble onto solid surfaces. The focus is on neutron reflectometry studies providing information on the density and magnetization depth profiles of buried interfaces. Specific attention is given to the near-interface "wetting" layer and to examples of magnetite nanoparticles on a hydrophilic silicon crystal, one coated with (3-Aminopropyl)triethoxysilane, and finally, one with a magnetic film with out-of-plane magnetization.

Nanoparticle processing: Understanding and controlling aggregation

Nanoparticles (NPs) are commonly defined as particles with size <100 nm and are currently of considerable technological and academic interest, since they are often the starting materials for nanotechnology. Novel properties develop as a bulk material is reduced to nanodimensions and is reflected in new chemistry, physics and biology. With reduction in size, a greater function of the atoms is at the surface, and promote different interaction with its environment, as compared to the bulk material. In addition, the reduction in size alters the electronic structure of the material, resulting in novel quantum effects. Size also influences mobility, primarily controlled by Brownian motion for NPs, and relevant in biological and environmental processes. However, the small size also leads to high surface energy, and NPs tend to aggregate, thereby lowering the surface energy. In all applications, the uncontrolled aggregation of NPs can have negative effects and needs to be avoided. There are however examples of controlled aggregation of NPs which give rise to novel effects. This review article is focused on the NP features that influences aggregation. Common strategies for synthesis of NPs from the gas and liquid phases are discussed with emphasis on aggregation during and after synthesis. The theory involving Van der Waals attractive force and electrical repulsive force as the controlling features of the stability of NPs is discussed, followed by examples of how repulsive and attractive forces can be manipulated experimentally to control NP aggregation. In some applications, NPs prepared by liquid methods need to be isolated for further applications. The process of solvent removal introduces new forces such as capillary forces that promote aggregation, in many cases, irreversibly. Strategies for controlling aggregation upon drying are discussed. There are also many methods for redispersing aggregated NPs, which involve mechanical forces, as well as manipulating capillary forces and surface characteristics. We conclude this review with a discussion of aggregation relevant real-world applications of NPs. This review should be relevant for scientists and technologists interested in NPs, since emphasis has been on the practical aspects of NP-based technology, and especially, strategies relevant to controlling NP aggregation.

Diosgenin-conjugated PCL–MPEG polymeric nanoparticles for the co-delivery of anticancer drugs: design, optimization, in vitro drug release and evaluation of anticancer activity

In this study, a polymeric nanoparticle-mediated dual anti-cancer drug delivery system was designed and developed.

Antifungal Activity of Amphotericin B Conjugated to Nanosized Magnetite in the Treatment of Paracoccidioidomycosis

This study reports on in vitro and in vivo tests that sought to assess the antifungal activity of a newly developed magnetic carrier system comprising amphotericin B loaded onto the surface of pre-coated (with a double-layer of lauric acid) magnetite nanoparticles. The in vitro tests compared two drugs; i.e., this newly developed form and free amphotericin B. We found that this nanocomplex exhibited antifungal activity without cytotoxicity to human urinary cells and with low cytotoxicity to peritoneal macrophages. We also evaluated the efficacy of the nanocomplex in experimental paracoccidioidomycosis. BALB/c mice were intratracheally infected with Paracoccidioides brasiliensis and treated with the compound for 30 or 60 days beginning the day after infection. The newly developed amphotericin B coupled with magnetic nanoparticles was effective against experimental paracoccidioidomycosis, and it did not induce clinical, biochemical or histopathological alterations. The nanocomplex also did not induce genotoxic effects in bone marrow cells. Therefore, it is reasonable to believe that amphotericin B coupled to magnetic nanoparticles and stabilized with bilayer lauric acid is a promising nanotool for the treatment of the experimental paracoccidioidomycosis because it exhibited antifungal activity that was similar to that of free amphotericin B, did not induce adverse effects in therapeutic doses and allowed for a reduction in the number of applications.

Lung fungal infections are caused by pathogens inhaled as spores which convert into invasive yeast forms in the lungs. This type of infection can spread to other sites in the body through the blood and lymphatic systems, sometimes leading to ulcerations and skin lesions. The drug of choice for treatment is Amphotericin B (AmB). AmB is a typical polyene with broad-spectrum antifungal activity that encounters some use limitations because of its side effects. We developed a magnetic carrier nanocomplex comprising of amphotericin B loaded onto the surface of magnetite nanoparticles pre-coated with a double-layer of lauric acid. We evaluated this approach for its antifungal activity against Paracoccidioides brasiliensis (strain Pb18) and its cytotoxicity in mammalian cell culture. We found that this nanocomplex exhibited antifungal activity without cytotoxicity to human urinary cells and low cytotoxicity to peritoneal macrophages. In vivo, the nanocomplex did not induce genotoxic effects in bone marrow cells and was effective against experimental paracoccidioidomycosis without inducing clinical, biochemical or histopathological alterations.

The impact of polymer coatings on magnetite nanoparticles performance as MRI contrast agents: a comparative study

BACKGROUND

Superparamagnetic iron oxide nanoparticles (SPIONs) are the most commonly used negative MRI contrast agent which affect the transverse (T2) relaxation time. The aim of the present study was to investigate the impact of various polymeric coatings on the performance of magnetite nanoparticles as MRI contrast agents.

METHODS

Ferrofluids based on magnetite (Fe3O4) nanoparticles (SPIONs) were synthesized via chemical co-precipitation method and coated with different biocompatible polymer coatings including mPEG-PCL, chitosan and dextran.

RESULTS

The bonding status of different polymers on the surface of the magnetite nanoparticles was confirmed by the Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA). The vibrating sample magnetometer (VSM) analysis confirmed the superparamagnetic behavior of all synthesized nanoparticles. The field-emission scanning electron microscopy (FE-SEM) indicated the formation of quasi-spherical nanostructures with the final average particle size of 12-55 nm depending on the type of polymer coating, and X-ray diffraction (XRD) determined inverse spinel structure of magnetite nanoparticles. The ferrofluids demonstrated sufficient colloidal stability in deionized water with the zeta potentials of -24.2, -16.9, +31.6 and -21 mV for the naked SPIONs, and for dextran, chitosan and mPEG-PCL coated SPIONs, respectively. Finally, the magnetic relaxivities of water based ferrofluids were measured on a 1.5 T clinical MRI instrument. The r2/r1 value was calculated to be 17.21, 19.42 and 20.71 for the dextran, chitosan and mPEG-PCL coated SPIONs, respectively.

CONCLUSIONS

The findings demonstrated that the value of r2/r1 ratio of mPEG-PCL modified SPIONs is higher than that of some commercial contrast agents. Therefore, it can be considered as a promising candidate for T2 MRI contrast agent.

Stable monodisperse nanomagnetic colloidal suspensions: An overview

Magnetic iron oxide nanoparticles (MNPs) have emerged as highly desirable nanomaterials in the context of many research works, due to their extensive industrial applications. However, they are prone to agglomerate on account of the anisotropic dipolar attraction, and therefore misled the particular properties related to single-domain magnetic nanostructures. The surface modification of MNPs is quite challenging for many applications, as it involves surfactant-coating for steric stability, or surface modifications that results in repulsive electrostatic force. Hereby, we focus on the dispersion of MNPs and colloidal stability.

Albumin-based micro-composite drug carriers with dual chemo-agents for targeted breast cancer treatment

Albumin-based drug-carrying micro-composite spheres were fabricated and studied to evaluate their potentials for breast cancer treatment. Magnetic nanoparticles and albumin were incorporated within poly(D l-lactide-co-glycolide) microspheres to increase accumulation of the microspheres at the target site. Two chemotherapeutics, cyclophosphamide and 5-fluorouracil, were encapsulated into the microspheres. The drug-release study revealed an initial burst of drug and then sustained release by diffusion. A Fourier transform infrared spectroscopy study confirmed the presence of all components of the drug delivery system. An in vitro study using fibroblast cells (3T3) and breast cancer cells (MDA-486) exhibited an effective cytotoxicity behavior when exposed to the drug delivery system in a dose- and time-dependent manner. The therapeutic influence of the drug delivery system was evaluated in vivo using a nude mouse breast cancer model. A continuous decrease in tumor size was observed in groups treated with microspheres containing the chemotherapeutics, whereas mice treated with direct chemotherapy without drug delivery system showed less efficacy and suggested tumor relapse after cessation of treatment. The enhanced therapeutic influence of the drug delivery system may be attributed to the increased uptake of the microspheres by malignant cells due to the presence of albumin and magnetic force. The bioavailability of chemotherapeutics at the target site was further increased due to the sustained release of the drugs by diffusion following the burst release. Continuous investigations will optimize the size of the drug delivery system and portions of the target driving-force components (magnetic nanoparticles and albumin) in the drug delivery system to maximize its therapeutic efficacy and minimize potential long-term side effects.

A numerical study of the phase behaviors of drug particle/star triblock copolymer mixtures in dilute solutions for drug carrier application

The complex microstructures of drug particle/ABA star triblock copolymer in dilute solutions have been investigated by a theoretical approach which combines the self-consistent field theory and the hybrid particle-field theory. Simulation results reveal that, when the volume fraction of drug particles is smaller than the saturation concentration, the drug particle encapsulation efficiency is 100%, and micelle loading capacity increases with increasing particle volume fraction. When the volume fraction of drug particles is equal to the saturation concentration, the micelles attain the biggest size, and micelle loading capacity reaches a maximum value which is independent of the copolymer volume fraction. When the volume fraction of drug particles is more than the saturation concentration, drug particle encapsulation efficiency decreases with increasing volume fraction of drug particles. Furthermore, it is found that the saturation concentration scales linearly with the copolymer volume fraction. The above simulation results are in good agreement with experimental results.

Solubilization, dispersion and stabilization of magnetic nanoparticles in water and non-aqueous solvents: recent trends

Solubilization and stabilization techniques for magnetic nanoparticles in water and in non-aqueous solvents are reviewed.

Preparation and characterization of novel water-based biodegradable polyurethane nanoparticles encapsulating superparamagnetic iron oxide and hydrophobic drugs

A green and novelin situmethod for the encapsulation of SPIO and hydrophobic drugs by PU NPs was developed, where drug release may be accelerated upon magnetic heating.

Synthesis, characterization and in vitro drug release of magnetic N-benzyl-O-carboxymethylchitosan nanoparticles loaded with indomethacin

Magnetic N-benzyl-O-carboxymethylchitosan nanoparticles were synthesized through incorporation and in situ methods and characterized by Fourier transform infrared spectroscopy, X-ray diffraction, differential scanning calorimetry, and magnetization measurements. Indomethacin was incorporated into the nanoparticles via the solvent evaporation method. The indomethacin-loaded magnetic nanoparticles were characterized by the same techniques, and also by transmission electron microscopy. The nanoparticles containing the polymer showed a drug loading efficiency of between 60.8% and 74.8%, and the magnetic properties were not significantly affected by incorporation of the drug. The in vitro drug release study was carried out in simulated body fluid, pH 7.4 at 37°C. The profiles showed an initial fast release, which became slower as time progressed. The percentage of drug released after 5 h was between 60% and 90%, and the best fitting mathematical model for drug release was the Korsmeyer-Peppas model, indicating a Fickian diffusion mechanism.