Sample preparation considerations for surface and crystalline properties and ecotoxicity of bare and silica-coated magnetite nanoparticles

Magnetic coagulometry: towards a new nanotechnological tool for ex vivo monitoring coagulation in human whole blood

Blood clotting disorders consisting of unwanted blood clot formation or excessive bleeding are some of the main causes of death worldwide. However, there are significant limitations in the current methods used to clinically monitor the dynamics of clot formation in human whole blood ex vivo. Here a new magnetic coagulometry platform for testing ex vivo coagulation is described. This platform exploits the sensitivity of the out-of-phase component of alternating current (AC) magnetic susceptibility (χ'') to variations in mobility and agglomeration of magnetic nanoparticles when trapped during blood clot formation. By labelling human whole blood with magnetic nanoparticles, the out-of-phase component of AC magnetic susceptibility shows that the dynamics of blood clot formation correlates with a decrease in the out-of-phase component χ'' over time activation of coagulation. This is caused by a rapid immobilisation of nanoparticles upon blood coagulation and compaction. In contrast, this rapid fall in the out-of-phase component χ'' is significantly slowed down when blood is pre-treated with three different anticoagulant drugs. Remarkably, the system showed sensitivity towards the effect of clinically used direct oral anticoagulation (DOAC) drugs in whole blood coagulation, in contrast to the inability of clinical routine tests prothrombin time (PT) and partial thromboplastin time (PTT) to efficiently monitor this effect. Translation of this nanomagnetic approach into clinic can provide a superior method for monitoring blood coagulation and improve the efficiency of the current diagnostic techniques.

pH-Responsible Doxorubicin-Loaded Fe3O4@CaCO3 Nanocomposites for Cancer Treatment

A magnetic nanocomposite (MNC) is an integrated nanoplatform that combines a set of functions of two types of materials. A successful combination can give rise to a completely new material with unique physical, chemical, and biological properties. The magnetic core of MNC provides the possibility of magnetic resonance or magnetic particle imaging, magnetic field-influenced targeted delivery, hyperthermia, and other outstanding applications. Recently, MNC gained attention for external magnetic field-guided specific delivery to cancer tissue. Further, drug loading enhancement, construction stability, and biocompatibility improvement may lead to high progress in the area. Herein, the novel method for nanoscale Fe3O4@CaCO3 composites synthesis was proposed. For the procedure, oleic acid-modified Fe3O4 nanoparticles were coated with porous CaCO3 using an ion coprecipitation technique. PEG-2000, Tween 20, and DMEM cell media was successfully used as a stabilization agent and template for Fe3O4@CaCO3 synthesis. Transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, and dynamic light scattering (DLS) data were used for the Fe3O4@CaCO3 MNC’s characterization. To improve the nanocomposite properties, the concentration of the magnetic core was varied, yielding optimal size, polydispersity, and aggregation ability. The resulting Fe3O4@CaCO3 had a size of 135 nm with narrow size distributions, which is suitable for biomedical applications. The stability experiment in various pH, cell media, and fetal bovine serum was also evaluated. The material showed low cytotoxicity and high biocompatibility. An excellent anticancer drug doxorubicin (DOX) loading of up to 1900 µg/mg (DOX/MNC) was demonstrated. The Fe3O4@CaCO3/DOX displayed high stability at neutral pH and efficient acid-responsive drug release. The series of DOX-loaded Fe3O4@CaCO3 MNCs indicated effective inhibition of Hela and MCF-7 cell lines, and the IC 50 values were calculated. Moreover, 1.5 μg of the DOX-loaded Fe3O4@CaCO3 nanocomposite is sufficient to inhibit 50% of Hela cells, which shows a high prospect for cancer treatment. The stability experiments for DOX-loaded Fe3O4@CaCO3 in human serum albumin solution indicated the drug release due to the formation of a protein corona. The presented experiment showed the “pitfalls” of DOX-loaded nanocomposites and provided step-by-step guidance on efficient, smart, anticancer nanoconstruction fabrication. Thus, the Fe3O4@CaCO3 nanoplatform exhibits good performance in the cancer treatment area.

Functionalized Magnetite Nanoparticles: Characterization, Bioeffects, and Role of Reactive Oxygen Species in Unicellular and Enzymatic Systems

The current study evaluates the role of reactive oxygen species (ROS) in bioeffects of magnetite nanoparticles (MNPs), such as bare (Fe3O4), humic acids (Fe3O4-HA), and 3-aminopropyltriethoxysilane (Fe3O4-APTES) modified MNPs. Mössbauer spectroscopy was used to identify the local surrounding for Fe atom/ions and the depth of modification for MNPs. It was found that the Fe3O4-HA MNPs contain the smallest, whereas the Fe3O4-APTES MNPs contain the largest amount of Fe2+ ions. Bioluminescent cellular and enzymatic assays were applied to monitor the toxicity and anti-(pro-)oxidant activity of MNPs. The contents of ROS were determined by a chemiluminescence luminol assay evaluating the correlations with toxicity/anti-(pro-)oxidant coefficients. Toxic effects of modified MNPs were found at higher concentrations (>10−2 g/L); they were related to ROS storage in bacterial suspensions. MNPs stimulated ROS production by the bacteria in a wide concentration range (10−15−1 g/L). Under the conditions of model oxidative stress and higher concentrations of MNPs (>10−4 g/L), the bacterial bioassay revealed prooxidant activity of all three MNP types, with corresponding decay of ROS content. Bioluminescence enzymatic assay did not show any sensitivity to MNPs, with negligible change in ROS content. The results clearly indicate that cell-membrane processes are responsible for the bioeffects and bacterial ROS generation, confirming the ferroptosis phenomenon based on iron-initiated cell-membrane lipid peroxidation.