Ligand-free template-assisted synthesis of stable perovskite nanocrystals with near-unity photoluminescence quantum yield within the pores of vaterite spheres.

Ligand-free methods for the synthesis of halide perovskite nanocrystals are of great interest because of their excellent performance in optoelectronics and photonics. In addition, template-assisted synthesis methods have become a powerful tool for the fabrication of environmentally stable and bright nanocrystals. Here we develop a novel approach for the facile ligand-free template-assisted fabrication of perovskite nanocrystals with a near-unity absolute quantum yield, which involves CaCO3 vaterite micro- and submicrospheres as templates. We show that the optical properties of the obtained nanocrystals are affected not mainly by the template morphology, but strongly depend on the concentration of precursor solutions, anion and cation ratio, as well as on adding defect-passivating rare-earth dopants. The optimized samples are further tested as infrared radiation visualizers exhibiting promising characteristics comparable to those that are commercially available.

Hierarchical Porous Magnetite Structures: From Nanoparticle Assembly to Monolithic Aerogels.

The development of universal methods to synthesize materials with different structures is always in the researchers' focus. Despite the fact that various structures based on magnetite have already been obtained, synthetic approaches that allow to synthesize materials with a wide range of texture and functional properties are still very poorly presented. In this work, we demonstrate that a stable magnetite hydrosol can be easily converted into monolithic structures of xero-, cryo- and aerogel by careful varying concentrations and drying conditions. We have also theoretically explained the observed effects by studying the percolation threshold at the sol-gel transition by means of controlled assembly of magnetite nanoparticles. At the calculated percolation point three types of materials different in porous organization were obtained. Due to the high biocompatibility of magnetite nanoparticles, the materials obtained were evaluated for cytotoxicity on HeLa cells line. All synthesized magnetite structures show excellent biocompatibility and minor cytotoxic effects at concentrations up to 1 µg mL-1. Considering that the porosity of materials can influence the manifestation of the hemostatic effect, whole-blood clotting study revealed the hemostatic potential of magnetite aerogel. That fact can be explained by presence spongy structure of the aerogel that allowed blood to be rapidly absorbed through full contact.

Shape anisotropic magnetic thrombolytic actuators: synthesis and systematic behavior study.

Thrombosis-related diseases are undoubtedly the deadliest disorders. During the last decades, numerous attempts were made to reduce the overall death rate and severe complications caused by treatment delays. Significant progress has been made in the development of nanostructured thrombolytics, especially magnetically controlled. The emergence of thrombolytic magnetic actuators, which can deliver tPA to the occlusion zone and perform mechanical disruption of the fibrin network under the application of a rotating magnetic field (RMF), can be considered for the next generation of thrombolytic drugs. Thus, we propose a systematic study of magnetic-field mediated mechanically-assisted thrombolysis (MFMMAT) for the first time. Four types of magnetic particles with different morphology and dimensionality were utilized to assess their impact on model clot lysis under different RMF parameters. Chain-like 1D and sea urchins-like 3D structures were found to be the most effective, increasing thrombolysis efficacy to nearly 200%. The drastic difference was also observed during the dissolution of 3 days old blood clots. Pure plasminogen activator had almost no effect on clot structure during 30 minutes of treatment while applying MFMMAT led to the significant decrease of clot area, thus uncovering the possibility of deep venous thrombosis therapy.

Cationic Magnetite Nanoparticles for Increasing siRNA Hybridization Rates.

An investigation of the interaction principles of nucleic acids and nanoparticles is a priority for the development of theoretical and methodological approaches to creating bionanocomposite structures, which determines the area and boundaries of biomedical use of developed nanoscale devices. «Nucleic acid-magnetic nanoparticle¼ type constructs are being developed to carry out the highly efficient detection of pathogens, create express systems for genotyping and sequencing, and detect siRNA. However, the data available on the impact of nanoparticles on the behavior of siRNA are insufficient. In this work, using nanoparticles of two classical oxides of inorganic chemistry (magnetite (Fe3O4) and silica (SiO2) nanoparticles), and widely used gold nanoparticles, we show their effect on the rate of siRNA hybridization. It has been determined that magnetite nanoparticles with a positive charge on the surface increase the rate of siRNA hybridization, while negatively charged magnetite and silica nanoparticles, or positively charged gold nanoparticles, do not affect hybridization rates (HR).

Effects of Metal Oxide Nanoparticles on Toll-Like Receptor mRNAs in Human Monocytes.

For the widespread application of nanotechnology in biomedicine, it is necessary to obtain information about their safety. A critical problem is presented by the host immune responses to nanomaterials. It is assumed that the innate immune system plays a crucial role in the interaction of nanomaterials with the host organism. However, there are only fragmented data on the activation of innate immune system factors, such as toll-like receptors (TLRs), by some nanoparticles (NPs). In this study, we investigated TLRs' activation by clinically relevant and promising NPs, such as Fe3O4, TiO2, ZnO, CuO, Ag2O, and AlOOH. Cytotoxicity and effects on innate immunity factors were studied in THP-1(Tohoku Hospital Pediatrics-1) cell culture. NPs caused an increase of TLR-4 and -6 expression, which was comparable with the LPS-induced level. This suggests that the studied NPs can stimulate the innate immune system response inside the host. The data obtained should be taken into account in future research and to create safe-by-design biomedical nanomaterials.

Toxicity Patterns of Clinically Relevant Metal Oxide Nanoparticles.

Nanostructured drugs are being approved for clinical use, although there is a serious deficit of systematic studies of these materials. Data on toxicity of nanoparticles (NPs) can vary due to different methods of preparation, size, and shape. We investigated the toxicity against cultured human cells, the acute toxicity in mice, and the influence on conjugative transfer of antibiotic resistance genes of clinically relevant NPs such as TiO2, ZrO2, HfO2, Ta2O5, Fe3O4, and AlOOH. NPs were synthesized as aqueous sols by the same method in aqueous solution, with almost identical size 2-10 nm. None of these NPs was cytotoxic at concentrations compatible with water solubility. Furthermore, TiO2, HfO2, Ta2O5, Fe3O4, and AlOOH were not toxic to mice after oral administration. However, ZrO2 showed rather high toxicity, with LD50 2277.8 mg/kg. Experiments with plasmid transfer between bacteria demonstrated that AlOOH NPs were the most hazardous since this material promoted the emergence of resistance to antibiotics. Thus, although our metal oxide NPs are largely non-toxic, their properties may differ in specific biological situations.

Magnetite Nanocontainers: Toward Injectable Highly Magnetic Materials for Targeted Drug Delivery.

Nanocontainers based solely on magnetite NPs have been synthesized by indirect gelation of stable magnetite hydrosol at ambient temperature using the microemulsion-assisted sol-gel method. Containers synthesized have adjustable size and consist of ∼10 nm magnetite nanoparticles linked by Fe-O-Fe interparticle bonds. The material demonstrates high magnetization values up to 60 emu/g and low cytotoxicity against both HeLa and postnatal human fibroblast (up to 260 µg/mL). The systems developed are perspective as a drug depot, particularly for magnetically controlled thrombolysis.

Composites based on heparin and MIL-101(Fe): the drug releasing depot for anticoagulant therapy and advanced medical nanofabrication.

We describe the synthesis and properties of a new composite material based on heparin and MIL-101(Fe) metal-organic framework. The intrinsic instability of MIL-101(Fe) towards hydrolysis enables binding of heparin molecules to the framework structure as is evidenced by DFT calculations and adsorption experiments. The de novo formed heparin-MOF composites showed good biocompatibility in in vitro and demonstrated pronounced anticoagulant activity. The specific interaction between the bioactive molecule and the carrier is critical for the selective degradation of the complex in the body fluids and for the enhanced activity. Hep_MIL-101(Fe) composite could serve as a drug-releasing depot for nanofabrication and to introduce anticoagulant activity to medical devices and biocoatings. Addition of Hep_MIL-101(Fe) to a sol-gel derived thrombolytic matrix allowed the combination of anticoagulant and thrombolytic activities in a single hybrid nanomaterial that could be applied as a bioactive nanocoating for PTFE vein implants.

A pure magnetite hydrogel: synthesis, properties and possible applications.

A magnetite-only hydrogel was prepared for the first time by weak base mediated gelation of stable magnetite hydrosols at room temperature. The hydrogel consists of 10 nm magnetite nanoparticles linked by interparticle Fe-O-Fe bonds and has the appearance of a dark-brown viscous thixotropic material. The water content in the hydrogel could be up to 93.6% by mass while volume fraction reaches 99%. The material shows excellent biocompatibility and minor cytotoxic effects at concentrations up to 207 µg mL-1. The gel shows excellent sorption capacity for heavy metal adsorption such as chrome and lead ions, which is 225% more than the adsorption capacity of magnetite nanoparticles. Due to thixotropic nature, the gel demonstrates mechanical stimuli-responsive release behavior with up to 98% release triggered by ultrasound irradiation. The material shows superparamagnetic behavior with a coercivity of 65 emu g-1 at 6000 Oe. The magnetite gels prepared could be used for the production of magnetite aerogels, magnetic drug delivery systems with controlled release and highly efficient sorbents for hydrometallurgy.