Advances in the Toxicity Assessment of Silver Nanoparticles Derived from a Extract for Monolayers and Spheroids.

The production of nanomaterials through environmentally friendly methods is a top priority in the sustainable development of nanotechnology. This paper presents data on the synthesis of silver nanoparticles using an aqueous extract of moss at room temperature. The morphology, stability, and size of the nanoparticles were analyzed using various techniques, including transmission electron microscopy, Doppler laser velocimetry, and UV-vis spectroscopy.

Micropatterning of biologically derived surfaces with functional clay nanotubes.

Micropatterning of biological surfaces performed via assembly of nano-blocks is an efficient design method for functional materials with complex organic-inorganic architecture. Halloysite clay nanotubes with high aspect ratios and empty lumens have attracted widespread interest for aligned biocompatible composite production. Here, we give our vision of advances in interfacial self-assembly techniques for these natural nanotubes.

Architectural design of core-shell nanotube systems based on aluminosilicate clay.

A nanoarchitectural approach to the design of functional nanomaterials based on natural aluminosilicate nanotubes and their catalysis, and practical applications are described in this paper. We focused on the buildup of hybrid core-shell systems with metallic or organic molecules encased in aluminosilicate walls, and nanotube templates for structured silica and zeolite preparation. The basis for such an architectural design is a unique AlO/SiO dual chemistry of 50 nm diameter halloysite tubes.

Photoinduced Antibacterial Activity and Cytotoxicity of CdS Stabilized on Mesoporous Aluminosilicates and Silicates.

Inactivation of bacteria under the influence of visible light in presence of nanostructured materials is an alternative approach to overcome the serious problem of the growing resistance of pathogenic bacteria to antibiotics. Cadmium sulfide quantum dots are superefficient photocatalytic material suitable for visible light transformation. In this work, CdS nanoparticles with size of less than 10 nm (QDs) were synthesized on the surface of natural and synthetic mesoporous aluminosilicates and silicates (halloysite nanotubes, MCM-41, MCM-41/Halloysite, SBA-15).

Prokaryotic and eukaryotic toxicity of halloysite decorated with photoactive nanoparticles.

The development of new approaches to treat the growing antibiotic resistance of pathogenic bacterial species is an important task to ensure the future safety of society. Utilization of irradiation of different wavelengths together with nanostructured materials based on metal containing nanoparticles may result in synergetic antibacterial effects. In this paper we aim to show the main conceptions of light-assisted bacteria deactivation techniques and prospects of application of natural clay nanotubes as a carrier for scalable photoactive antibacterial nanomaterials.

Natural aluminosilicate nanotubes loaded with RuCo as nanoreactors for Fischer-Tropsch synthesis.

Following nanoarchitectural approach, mesoporous halloysite nanotubes with internal surface composed of alumina were loaded with 5-6 nm RuCo nanoparticles by sequential loading/reduction procedure. Ruthenium nanoclusters were loaded inside clay tube by microwave-assisted method followed by cobalt ions electrostatic attraction to ruthenium during wetness impregnation step. Developed nanoreactors with bimetallic RuCo nanoparticles were investigated as catalysts for the Fischer-Tropsch process.

Biodistribution of Quantum Dots-Labelled Halloysite Nanotubes: A In Vivo Study.

Halloysite is a promising building block in nanoarchitectonics of functional materials, especially in the development of novel biomaterials and smart coatings. Understanding the behavior of materials produced using halloysite nanotubes within living organisms is essential for their safe applications. In this study, quantum dots of different compositions were synthesized on the surface of modified clay nanotubes, and the biodistribution of this hybrid material was monitored within nematodes.

Clay Nanotube Immobilization on Animal Hair for Sustained Anti-Lice Protection.

Topical administration of drugs is required for the treatment of parasitic diseases and insect infestations; therefore, fabrication of nanoscale drug carriers for effective insecticide topical delivery is needed. Here we report the enhanced immobilization of halloysite tubule nanoclay onto semiaquatic capybaras which have hydrophobic hair surfaces as compared to their close relatives, land-dwelling guinea pigs, and other agricultural livestock. The hair surface of mammals varies in hydrophobicity having a cortex surrounded by cuticles.

Ru/CdS Quantum Dots Templated on Clay Nanotubes as Visible-Light-Active Photocatalysts: Optimization of S/Cd Ratio and Ru Content.

A nanoarchitectural approach based on in situ formation of quantum dots (QDs) within/outside clay nanotubes was developed. Efficient and stable photocatalysts active under visible light were achieved with ruthenium-doped cadmium sulfide QDs templated on the surface of azine-modified halloysite nanotubes. The catalytic activity was tested in the hydrogen evolution reaction in aqueous electrolyte solutions under visible light.

Ruthenium-Loaded Halloysite Nanotubes as Mesocatalysts for Fischer-Tropsch Synthesis.

Halloysite aluminosilicate nanotubes loaded with ruthenium particles were used as reactors for Fischer-Tropsch synthesis. To load ruthenium inside clay, selective modification of the external surface with ethylenediaminetetraacetic acid, urea, or acetone azine was performed. Reduction of materials in a flow of hydrogen at 400 °C resulted in catalysts loaded with 2 wt.

Development of Marine Antifouling Epoxy Coating Enhanced with Clay Nanotubes.

An antifouling epoxy resin doped with natural clay nanotubes that are loaded with biocide or silver allowed extended protection against the proliferation of marine microorganisms. Compared to the 2-3 months of protection with antifoulant dichlorooctylisothiazolone (DCOIT) directly admixed into epoxy resin, the DCOIT release time of the halloysite formulations was extended to 12 months by incorporating biocide-loaded nanoclay in the polymer matrix. The protective properties of the epoxy-halloysite nanocomposites showed much less adhesion and proliferation of marine bacteria on the resin surface after a two-month exposure to seawater than the coating formulations directly doped with non-encapsulated DCOIT.

Antimicrobial Applications of Clay Nanotube-Based Composites.

Halloysite nanotubes with different outer surface/inner lumen chemistry (SiO/AlO) are natural objects with a 50 nm diameter hollow cylindrical structure, which are able to carry functional compounds both inside and outside. They are promising for biological applications where their drug loading capacity combined with a low toxicity ensures the safe interaction of these nanomaterials with living cells. In this paper, the antimicrobial properties of the clay nanotube-based composites are reviewed, including applications in microbe-resistant biocidal textile, paints, filters, and medical formulations (wound dressings, drug delivery systems, antiseptic sprays, and tissue engineering scaffolds).

Templated self-assembly of ordered mesoporous silica on clay nanotubes.

A novel self-assembly strategy of ordered silica arrays on halloysite clay nanotubes allows us to obtain mesoporous MCM-41 materials with enhanced thermal and mechanical stability. The formation of a structured mesoporous silica phase on halloysite is based on the assembly of cationic amphiphilic molecules onto a negative nanotube surface. The resulting MCM-41/halloysite composite demonstrated thermal and mechanical stability up to 1100 °C and 500 MPa showing great potential for application of mesoporous materials as industrial catalyst carriers and adsorbents.

Interfacial Self-Assembly in Halloysite Nanotube Composites.

A self-assembly of clay nanotubes in functional arrays for the production of organized organic/inorganic heterostructures is described. These 50-nm-diameter natural alumosilicate nanotubes are biocompatible. Halloysite allows for 10-20 wt % chemical/drug loading into the inner lumen, and it gives an extended release for days and months (anticorrosion, self-healing, flame-retardant, antifouling, and antibacterial composites).

Fluorescence and Cytotoxicity of Cadmium Sulfide Quantum Dots Stabilized on Clay Nanotubes.

Quantum dots (QD) are widely used for cellular labeling due to enhanced brightness, resistance to photobleaching, and multicolor light emissions. CdS and CdZn₁S nanoparticles with sizes of 6⁻8 nm were synthesized via a ligand assisted technique inside and outside of 50 nm diameter halloysite clay nanotubes (QD were immobilized on the tube's surface). The halloysite⁻QD composites were tested by labeling human skin fibroblasts and prostate cancer cells.

Nanoparticles Formed onto/into Halloysite Clay Tubules: Architectural Synthesis and Applications.

Nanoparticles, being objects with high surface area are prone to agglomeration. Immobilization onto solid supports is a promising method to increase their stability and it allows for scalable industrial applications, such as metal nanoparticles adsorbed to mesoporous ceramic carriers. Tubular nanoclay - halloysite - can be an efficient solid support, enabling the fast and practical architectural (inside / outside) synthesis of stable metal nanoparticles.

Rapid and Controlled In Situ Growth of Noble Metal Nanostructures within Halloysite Clay Nanotubes.

A rapid (≤2 min) and high-yield low-temperature synthesis has been developed for the in situ growth of gold nanoparticles (NPs) with controlled sizes in the interior of halloysite nanotubes (HNTs). A combination of HAuCl in ethanol/toluene, oleic acid, and oleylamine surfactants and ascorbic acid reducing agent with mild heating (55 °C) readily lead to the growth of targeted nanostructures. The sizes of Au NPs are tuned mainly by adjusting nucleation and growth rates.

Investigation of the ozonation products of natural complex mixtures using Fourier transform ion cyclotron resonance mass spectrometry.

Natural complex mixtures such as oil and dissolved organic matter play an important role in the economy and in the global carbon cycle. One of the most promising approaches for the investigation of the chemical structure of such substances is the combination of the high-resolution mass spectrometry and selective chemical reactions. Here, we report the investigation of the ozonation products of natural complex mixtures using Fourier transform ion cyclotron resonance mass spectrometry.

Formation of metal clusters in halloysite clay nanotubes.

We developed ceramic core-shell materials based on abundant halloysite clay nanotubes with enhanced heavy metal ions loading through Schiff base binding. These clay tubes are formed by rolling alumosilicate sheets and have diameter of .50 nm, a lumen of 15 nm and length ~1 μm.