Palladium nanoparticles deposited on silanized halloysite nanotubes: synthesis, characterization and enhanced catalytic property

Hal-Py-SO3H as a novel and recyclable catalyst for highly efficient synthesis of xanthene and spiropyran derivatives

The aim of this research is to synthesize a new sulfonic acid catalyst based on halloysite nanotubes (Hal-Py-SO3H) and characterize it as a solid acid nanocatalyst by various analytical techniques such as Fourier-Transformed Infrared spectroscopy (FTIR), Thermal gravimetric Analysis (TGA), X-ray Diffraction (XRD) analysis, Scanning Electron Microscopy (SEM), Vibrating Energy-Dispersive X-ray analysis (EDX), Transmission electron microscopy (TEM) and X-ray atomic mapping. Furthermore, this new catalyst was evaluated in synthesizing spiropyran derivatives via multicomponent reactions (MCRs) and Xanthen derivatives under environmentally sustainable conditions. The main advantages of this approach include green conditions, excellent yields, quick reaction rates, and ease of preparation. Additionally it was observed that the catalyst exhibited robust stability even after multiple recycling processes, indicating its potential for practical applications in sustainable chemical transformations.

Enhanced Antibacterial Activity at Ag-Cu Nanojunctions: Unveiling the Mechanism with Simple Surfaces of CuNPs-on-Ag Films

Deposition of CuNPs on silver film gives rise to the formation of active Ag-Cu interfaces leading to dramatic enhancements in antibacterial activity against Escherichia coli. Transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDAX) analyses reveal that CuNPs are covered in a thin Cu2O shell, while X-ray photoelectron spectroscopy measurements (XPS) reveal that the Ag film samples contain significant amounts of Ag2O. XPS analyses show that the deposition of CuNPs on Ag films leads to the formation of a photoactive Ag2O-Cu2O heterostructure. Following a Z-scheme mechanism, electrons from the conduction band of Ag2O recombine with photogenerated holes from the valence band of Cu2O. Consequently, electrons at Cu2O's conduction band render Cu reduced and cause reductive activation of surface oxygen species on Cu forming reactive oxygen species (ROS). Interaction between metallic Cu and ROS species leads to the formation of a Cu(OH)2 phase. Both ROS and Cu(OH)2 species have previously been reported to lead to enhanced antibacterial properties. Holes on Ag2O produce a highly oxidized AgO phase, a phase reported to exhibit excellent antibacterial properties. Quantitative analysis of Cu and Ag high-resolution X-ray photoelectron spectroscopy (HR-XPS) spectra directly reveals several-fold increases in these active phases in full agreement with the observed increase in antibacterial activities. This study provides insight and surface design parameters by elucidating the important roles of Ag and Cu's bifunctionality as active antibacterial materials.

PEO Coatings Modified with Halloysite Nanotubes: Composition, Properties, and Release Performance

In this work, the properties of the coatings formed on the Mg-Mn-Ce alloy by plasma electrolytic oxidation (PEO) in electrolytes containing halloysite nanotubes (HNTs) were investigated. The incorporation of halloysite nanotubes into the PEO coatings improved their mechanical characteristics, increased thickness, and corrosion resistance. The studied layers reduced corrosion current density by more than two times in comparison with the base PEO layer without HNTs (from 1.1 × 10^-7 A/cm² to 4.9 × 10^-8 A/cm²). The presence of halloysite nanotubes and products of their dihydroxylation that were formed under the PEO conditions had a positive impact on the microhardness of the obtained layers (this parameter increased from 4.5 ± 0.4 GPa to 7.3 ± 0.5 GPa). In comparison with the base PEO layer, coatings containing halloysite nanotubes exhibited sustained release and higher adsorption capacity regarding caffeine.

XPS, structural and antimicrobial studies of novel functionalized halloysite nanotubes

A novel robust preparation method based on thermal salt decomposition has been elaborated for synthesis of halloysite nanotubes (HNTs) impregnated with silver and iron oxide nanoparticles. The developed method is simple, time-effective, and can be employed for large scale material fabrication. Different characterization techniques, including X-ray diffraction (XRD), scanning and transmission electron spectroscopy (SEM and TEM) and energy dispersive X-ray spectroscopy (EDS) have been used to characterize the functionalized HNTs composite materials. Surface elemental and chemical state analysis was conducted using X-ray photoelectron spectrometer (XPS). The functionalized HNTs exhibit enhanced total surface area (by 17.5%) and pore volume (by 11%) compare to the raw HNTs calculated by using the Brunauer-Emmett-Teller (BET) method. It was shown that functionalized HNTs possess high antimicrobial properties towards both gram- positive and gram-negative bacteria species. The enhanced surface area and bactericidal properties of functionalized HNTs could be beneficial for employing of the prepared material as low cost filtration media for water treatment applications. Molecular dynamics (FPMD) were performed to obtain insights about possible physiochemical mechanisms for chemical adsorption and on the HNT thermal stability.

Synthesis and Optimization of Superhydrophilic-Superoleophobic Chitosan-Silica/HNT Nanocomposite Coating for Oil-Water Separation Using Response Surface Methodology

In this current study, facile, one-pot synthesis of functionalised nanocomposite coating with simultaneous hydrophilic and oleophobic properties was successfully achieved via the sol-gel technique. The synthesis of this nanocomposite coating aims to develop a highly efficient, simultaneously oleophobic-hydrophilic coating intended for polymer membranes to spontaneously separate oil-in-water emulsions, therefore, mitigating the fouling issue posed by an unmodified polymer membrane. The simultaneous hydrophilicity-oleophobicity of the nanocoating can be applied onto an existing membrane to improve their capability to spontaneously separate oil-in-water substances in the treatment of oily wastewater using little to no energy and being environmentally friendly. The synthesis of hybrid chitosan-silica (CTS-Si)/halloysite nanotube (HNT) nanocomposite coating using the sol-gel method was presented, and the resultant coating was characterised using FTIR, XPS, XRD, NMR, BET, Zeta Potential, and TGA. The wettability of the nanocomposite coating was evaluated in terms of water and oil contact angle, in which it was coated onto a polymer substrate. The coating was optimised in terms of oil and water contact angle using Response Surface Modification (RSM) with Central Composite Design (CCD) theory. The XPS results revealed the successful grafting of organosilanes groups of HNT onto the CTS-Si denoted by a wide band between 102.6-103.7 eV at Si^2p. FTIR spectrum presented significant peaks at 3621 cm^-1; 1013 cm^-1 was attributed to chitosan, and 787 cm^-1 signified the stretching of Si-O-Si on HNT. ²⁹Si, ²⁷Al, and ¹³H NMR spectroscopy confirmed the extensive modification of the particle's shells with chitosan-silica hybrid covalently linked to the halloysite nanotube domains. The morphological analysis via FESEM resulted in the surface morphology that indicates improved wettability of the nanocomposite. The resultant colloids have a high colloid stability of 19.3 mV and electrophoretic mobility of 0.1904 µmcm/Vs. The coating recorded high hydrophilicity with amplified oleophobic properties depicted by a low water contact angle (WCA) of 11° and high oil contact angle (OCA) of 171.3°. The optimisation results via RSM suggested that the optimised sol pH and nanoparticle loadings were pH 7.0 and 1.05 wt%, respectively, yielding 95% desirability for high oil contact angle and low water contact angle.

Application of Selenium Nanoparticles in Localized Drug Targeting for Cancer Therapy

BACKGROUND

Selenium nanoparticles (SeNPs) have gardened their place in the biomedical field and serve as a chemotherapeutic agent for targeted drug delivery due to their capacity to exert distinct mechanisms of action on cancer and normal cells. The principle behind these mechanisms is the generation of Reactive Oxygen Species (ROS) eventually leads to apoptosis via the dysfunction of various pathways. SeNPs, when used in higher concentrations, lead to toxicity; therefore, conjugation and surface functionalization not only improve their toxic nature but also enhance their anticancer activity.

OBJECTIVES

The primary goal of this analysis is to provide a thorough and systematic investigation into the use of various SeNPs in localized drug targeting for cancer therapy. This has been achieved by citing examples of numerous SeNPs and their use as a drug targeting agent for cancer therapy.

METHODS

All relevant data and information about the various SeNPs for drug targeting in cancer therapy were gathered from various databases, including Science Direct, PubMed, Taylor and Francis imprints, American Chemical Society, Springer, Royal Society of Chemistry, and Google scholar.

RESULTS

SeNPs are explored due to their better biopharmaceutical properties and their cytostatic behavior. Se, as an essential component of the enzyme glutathione peroxidase (GPx) and other seleno-chemical substances, might boost chemotherapeutic efficacy, and protect tissues from cellular damage caused by ROS. SeNPs have the potential to set the stage for developing new strategies to treat malignancy.

CONCLUSION

This review extensively analyzed the anticancer efficacy and functionalization strategies of SeNPs in drug delivery to cancer cells. In addition, this review highlights the mechanism of action of drug-loaded SeNPs to suppress the proliferation of cancer cells in different cell lines.

Ag nanoparticles immobilized on new magnetic alginate halloysite as a recoverable catalyst for reduction of nitroaromatics in aqueous media

Amines can be applied in the synthesis of various important compounds such as dyes, drugs, polymers, pharmaceutical products, and biologically active materials. The significant subject in the preparation of amines is the selection of the most effective heterogeneous catalyst to get the best catalytic efficiency, stability, recoverability, and reusability. For this target, we prepared new alginate magnetically recoverable nanocatalyst by stabilization of Ag nanoparticles on the surface of the halloysite (HS) [HS-Alginate-Ag/Fe₃O₄]. Several detection methods confirmed the production of HS-Alginate-Ag/Fe₃O₄ nanocatalyst and the results obtained were well explained in the context. HS-Alginate-Ag/Fe₃O₄ presented good catalytic performance for the hydrogenation of nitro compounds using NaBH₄ as the reducing agent and hydrogen donor. The good activity and durability of this catalyst can be attributed to the good dispersion and nano-sized particle of silver nanoparticles.

Preparation and Performance of Porous Carbon Nanocomposite from Renewable Phenolic Resin and Halloysite Nanotube

The growing demand for high performance from supercapacitors has inspired the development of porous nanocomposites using renewable and naturally available materials. In this work, a formaldehyde-free phenolic resin using monosaccharide-based furfural was synthesized to act as the carbon precursor. One dimensional halloysite nanotube (HNT) with high porosity and excellent cation/anion exchange capacity was mixed with the phenol-furfural resin to fabricate carbonaceous nanocomposite HNT/C. Their structure and porosity were characterized. The effects of the halloysite nanotube amount and carbonization temperature on the electrochemical properties of HNT/C were explored. HNT/C exhibited rich porosity, involving a large specific surface area 253 m²·g⁻¹ with a total pore volume of 0.27 cm³·g⁻¹. The electrochemical performance of HNT/C was characterized in the three-electrode system and showed enhanced specific capacitance of 146 F·g⁻¹ at 0.2 A g⁻¹ (68 F·g⁻¹ for pristine carbon) in electrolyte (6 mol·L⁻¹ KOH) and a good rate capability of 62% at 3 A g⁻¹. It also displayed excellent cycle performance with capacitance retention of 98.5% after 500 cycles. The symmetric supercapacitors with HNT/C-1:1.5-800 electrodes were fabricated, exhibiting a high energy density of 20.28 Wh·Kg⁻¹ at a power density of 100 W·Kg⁻¹ in 1 M Na₂SO₄ electrolyte. The present work provides a feasible method for preparing composite electrode materials with a porous structure from renewable phenol-furfural resin and HNT. The excellent supercapacitance highlights the potential applications of HNT/C in energy storage.

Controlled synthesis of Zeolite adsorbent from low-grade diatomite: A case study of self-assembled sodalite microspheres

Highly efficient and sustainable conversion technologies to generate uniform sodalite (Na₈(AlSiO₄)₆(OH)₂) zeolite microspheres with low-grade waste natural diatomite as raw materials via a solution-mediated crystallization route were developed in the present study. The synthesis process can be considered as an in-situ zeolitization of diatomite precursor without involving any mesoscale template and any post-synthetic modification. The mass ratios of diatomite and AlCl₃·6H₂O have remarkable effect on the morphology, crystal structure and porosity of sodalite zeolite product. The preferred sodalite microspheres with uniform mesoporous of size 3.5-5.5 nm and large surface area of 162.5 m²/g exhibit well removal performance for heavy metal ions (Pb(II), Cd(II), Zn(II), and Cu(II)), with the highest adsorption abilities for Pb(II) ions of 365 mg/g. In addition, the effect of contact time, initial ion concentration, competitive adsorption and solution pH were evaluated. The removal performance results from synergistic effects of dominating cation-exchange and additional surface chemisorption. The study may broadly help unveil chemical control reactions of the zeolitization processes of diatomite, and thus facilitates the development of promising zeolite materials for the use in natural and engineered aquatic environments by recycling waste diatomite resources.

Palladium Nanoparticles on a Creatine-Modified Bentonite Support: An Efficient and Sustainable Catalyst for Nitroarene Reduction

Creatine as the nitrogen-rich, green and cheap compound is used for modification of natural bentonite and the resulting material is employed for the stabilization of Palladium nanoparticles having an average diameter of 3 nm. This new material bento-crt@Pd is characterized using different techniques such as X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), solid state UV-vis, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), and energy-dispersive X-ray spectroscopy (EDX). This green catalyst promotes efficient reduction of aromatic nitro compounds in aqueous media. By using this catalyst nitroarenes having electron donating as well as electron withdrawing groups were reduced efficiently to their corresponding amines at room temperature. The catalyst can be recycled seven times and the reused catalyst was characterized by TEM and XPS.

A general orientation distribution function for clay-rich media

The role of the preferential orientation of clay platelets on the properties of a wide range of natural and engineered clay-rich media is well established. However, a reference function for describing the orientation of clay platelets in these different materials is still lacking. Here, we conducted a systematic study on a large panel of laboratory-made samples, including different clay types or preparation methods. By analyzing the orientation distribution functions obtained by X-ray scattering, we identified a unique signature for the preferred orientation of clay platelets and determined an associated reference orientation function using the maximum-entropy method. This new orientation distribution function is validated for a large set of engineered clay materials and for representative natural clay-rich rocks. This reference function has many potential applications where consideration of preferred orientation is required, including better long-term prediction of water and solute transfer or improved designs for new generations of innovative materials.

A reference function for describing the orientation of clay platelets in clay-rich materials is still lacking, but is necessary for applications such as prediction of water and solute transfer and designs of innovative materials. Here, the authors determine a reference orientation function of clay platelets, and validate their function for both engineered and natural clay-rich media.

Pt-Cu Bimetallic Nanoparticles Loaded in the Lumen of Halloysite Nanotubes

In this study, we demonstrate that Pt-Cu bimetallic nanoparticles with different compositions (Pt₃Cu, PtCu, PtCu₃) can be loaded in the lumen of halloysite nanotube (HNT) via a simple one-pot reduction. Increasing the pH of metallic precursor (H₂PtCl₆ and CuCl₂)/HNT solutions enhances the dissociation of H₂PtCl₆, advancing the association of [PtCl₆]^2- with the positively charged inner surface (Al-OH) of HNT. Moreover, the shrinkage of bond length from Pt-Cl in [PtCl₆]^2- to Pt-O in [PtCl₄(OH)₂]^2- due to pH-modulated ligand exchange may also assist Pt(IV) being trapped inside the halloysite. In the meantime, Cu(II) cations may complex with Pt(IV) anions via electrostatic force that would help the formation of Pt-Cu bimetallic nanoparticles inside the halloysite. The obtained PtCu₃@HNT system shows a significantly enhanced catalytic performance in the reduction of 4-nitrophenol by sodium borohydride, with a mass activity approximating 60 times higher than that of unloaded Pt nanoparticles. The high catalytic efficiency can be maintained after thermal treatment at 200 or 400 °C.

Synergistic Effects of ppm Levels of Palladium on Natural Clinochlore for Reduction of Nitroarenes

Augmenting the modified naturally occurring clay clinochlore with ppm amounts of palladium leads to a new and very effective reagent for the reduction of numerous aromatic nitro species. When palladium nanoparticles are supported on pyridyltriazole-modified clinochlore, iron within clinochlore acts synergistically with palladium to catalyze the reduction of a wide variety of nitroarenes at room temperature in aqueous media. Based on E-factor calculations, the catalyst system is found to be in line with green chemistry standards and can be recycled up to five times.

Core-shell design and well-dispersed Pd particles for three-way catalysis: Effect of halloysite nanotubes functionalized with Schiff base

In this study, we have described the synthesis of core@shell three-way catalyst with well-dispersed Pd nanoparticles which were intercalated into halloysite nanotubes (HNTs) material via ligand assistance. The prepared parameters of Pd@HNTs catalyst included amine source, the molar ratio of amine and aldehyde, and the addition of CeO₂ promoter. As a result, Pd@HNTs performed a good dispersion of Pd particles and high stability, which is attributed to the strong interaction between Pd and HNTs with Schiff base ligands and the high thermal resistance of HNTs as a sintering barrier. Moreover, the results of various characteristic analyses revealed that Pd@HNT-E12 (ethylenediamine: salicylaldehyde in a molar ratio of 1:2) exhibited the highest gases conversion to the others, which has excellent redox ability. Furthermore, the addition of CeO₂, which acted as both a promoter and a protector, could provide more oxygen vacancies for promoting NO reduction and CO and C₃H₈ oxidation at gradually elevated temperatures. Such core-shell catalyst Ce@Pd@HNT-E12 could avoid excess CeO₂ penetrating into the pore volume of halloysite support and facilitate the three-way catalytic reaction.

Superhydrophobic Polyurethane Foam Coated with Polysiloxane-Modified Clay Nanotubes for Efficient and Recyclable Oil Absorption

Superhydrophobic polyurethane foam (PUF) is prepared by surface coating of halloysite nanotubes. The nanotubes were first modified by surface grafting with hexadecyltrimethoxysilane, followed by assembly on the PUF by dip coating. This treatment makes the water contact angle of the modified PUF higher than 150°. The modified foam has a highly selective absorption of oils and organic solvents. The absorption ratios of the modified PUF for chloroform and dichloroethane reached 104 and 74, respectively. Such superhydrophobic foam can maintain the oil absorption performance even after 10 absorption-squeezing cycles, demonstrating good recyclability. The modified foam can pick up oil or organic solvent continuously and quickly from water's surface. This hydrophobic nanotube coating also enhances the flame retardancy of the PUF, and the modified foam will extinguish itself maintaining its integrity. The preparation method for hydrophobic and flame-retardant PUF by coating with natural clay nanotubes is a simple process and promises scalable applications in oil-water separation.

Mesoporous halloysite nanotubes modified by CuFe2O4 spinel ferrite nanoparticles and study of its application as a novel and efficient heterogeneous catalyst in the synthesis of pyrazolopyridine derivatives

In this study, mesoporous halloysite nanotubes (HNTs) were modified by CuFe₂O₄ nanoparticles for the first time. The morphology, porosity and chemistry of the CuFe₂O₄@HNTs nanocomposite were fully characterized by Fourier transform infrared (FT-IR) spectroscopy, field-emission scanning electron microscopy (FE-SEM) image, transmission electron microscope (TEM) images, energy-dispersive X-ray (EDX), X-ray diffraction (XRD) pattern, Brunauer-Emmett-Teller (BET) adsorption-desorption isotherm, thermogravimetric (TG) and vibrating sample magnetometer (VSM) curve analyses. The results confirmed that CuFe₂O₄ with tetragonal structure, uniform distribution, and less agglomeration was located at HNTs. CuFe₂O₄@HNTs nanocomposite special features were high thermal stability, crystalline structure, and respectable magnetic property. SEM and TEM results showed the nanotube structure and confirmed the stability of basic tube in the synthetic process. Also, inner diameters of tubes were increased in calcination temperature at 500 °C. A good magnetic property of CuFe₂O₄@HNTs led to use it as a heterogeneous catalyst in the synthesis of pyrazolopyridine derivatives. High efficiency, green media, mild reaction conditions and easily recovery of the nanocatalyst are some advantages of this protocol.

TiO2 decorated functionalized halloysite nanotubes (TiO2@HNTs) and photocatalytic PVC membranes synthesis, characterization and its application in water treatment

In this study photocatalyst, TiO₂@HNTs were prepared by  synthesizing TiO₂ nanoparticles in situ on the  functionalized halloysite nanotubes (HNTs) surface. Photocatalytic PVC membrane TiO₂@HNTs M2 (2 wt.%) and TiO₂@HNTs M3 (3 wt.%) were also prepared. Photocatalyst TiO₂@HNTs and photocatalytic PVC membranes were used to study the photocatalytic activity against the methylene blue (MB) and rhodamine B (RB) dyes in UV batch reactor. The structure and morphology of photocatalyst and photocatalytic PVC membrane were characterized by fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), transmission electron microscopy (TEM), UV-Vis spectrophotometer and photoluminescence (PL). The PL study showed that the oxygen vacancies and surface hydroxyl groups present on the surface of TiO₂@HNTs act as excellent traps for charge carrier, reducing the electron-hole recombination rate.TiO₂@HNTs 2 (2 wt.%) and TiO₂@HNTs 3 (3 wt.%) degraded MB dye up to 83.21%, 87.47% and RB dye up to 96.84% and 96.87%, respectively. TiO₂@HNT photocatalyst proved to be stable during the three consecutive cycle of photocatalytic degradation of the RB dye. TiO₂@HNTs M2 and TiO₂@HNTs M3 degraded MB dye up to 27.19%, 42.37% and RB dye up to 30.78%, 32.76%, respectively. Photocatalytic degradation of both the dyes followed the first-order kinetic model. Degradation product analysis was done using the liquid chromatography–mass spectrometry (LC-MS) and the results showed that the dye degradation was initiated by demethylation of the molecule. MB and RB dye degradation reaction were tested by TBA and IPA as OH^* and H⁺ scavengers respectively. Mechanism of photocatalytic activity of TiO₂@HNTs and photocatalytic PVC membrane were also explained.

Evaluation of floor-wise pollution status and deposition behavior of potentially toxic elements and nanoparticles in air conditioner dust during urbanistic development

The study was undertaken to investigate deposition behaviors of various size-segregated particles and indoor air quality using dust accumulated on the air conditioner filter acting as a sink for PTEs and nanoparticles that can pose a significant health risk. However, the particulate matter size and chemical composition in AC dust and its relationship with PTEs remains uncertain. Current study aims to investigate the PTEs and nanoparticles composition of AC dust using different analytical approaches including ICP-MS, XRD, XPS, SEM/TEM along with EDS and Laser Diffraction particle size analyzer. The mean concentration of PTEs like Al, As, Cd, Cu, Li, Pb, Sb, Se, Sn, Ti, V and Zn exceeded the corresponding background value. Pb, As, Sn, Sb, Cd were categorizing under geo-accumulation index class IV. Most of the particles were found to be > 100 μm and it decreased significantly with increase in floor altitude. A significantly negative correlation was found between particles size and PTEs concentration showing a significant increase in PTEs content with decrease in particles size. The XPS results showed dominant peaks for TiO₂, Ti-O-N, As₂O₃, Fe⁺³, Fe⁺², Al-OH and Al₂0₃. Additionally, As, Pb, Si and Fe were dominant metallic nanoparticles identified using SEM/TEM along with EDS.

Rod in Tube: A Novel Nanoplatform for Highly Effective Chemo-Photothermal Combination Therapy toward Breast Cancer

Gold nanorods (GNRs) and doxorubicin (DOX) were loaded into the lumen of halloysite nanotubes (HNTs) via a rapid synthesis process (2 min) and physical adsorption. The targeting molecules of folic acid (FA) are then conjugated to HNTs via reactions with bovine serum albumin (BSA). The formation of GNRs in HNTs was verified by different techniques. Au-HNT-DOX@BSA-FA shows a maximum temperature of 26.8 °C rising after 8 min of 808 nm laser irradiation under 0.8 W cm^-2. The functionalized HNTs exhibited stronger chemotherapeutic effect under laser irradiation as the laser could promote the release of DOX and temperature rising. Au-HNT-DOX@BSA-FA-treated MCF-7 cells exhibited a survival rate of 7.4% after laser irradiation. Au-HNT-DOX@BSA-FA treatment does not induce obvious toxicity in blood biochemistry, liver, and kidney function in normal mice. In vivo chemo-photothermal treatment toward 4T1-bearing mice suggested that Au-HNT-DOX@BSA-FA exhibited remarkable tumor-targeted efficiency and good controlled release effect for DOX. Also, the nanoparticles exhibited a rapid photothermal performance and an ability to inhibit the growth of tumors. Because of the synergistic effect of chemical-photothermal therapy, the toxicity of DOX to normal tissues was reduced on the premise of ensuring the same curative effect with a low dosage of 0.32 mg kg^-1. This novel chemo-photothermal therapy nanoplatform provided a safe, rapid, effective, and cheap choice for the treatment of breast tumors both in vitro and in vivo.

Influence of Au/Pd alloy on an amine functionalised ZnCr LDH–MCM-41 nanocomposite: A visible light sensitive photocatalyst towards one-pot imine synthesis

Au/Pd loaded amine functionalised ZnCr LDH–MCM-41 photocatalyst for one-pot imine synthesis.

Transport Asymmetry of Novel Bi-Layer Hybrid Perfluorinated Membranes on the Base of MF-4SC Modified by Halloysite Nanotubes with Platinum

Three types of bi-layer hybrid nanocomposites on the base of perfluorinated cation-exchange membrane MF-4SC (Russian analogue of Nafion^®-117) were synthesized and characterized. It was found that two membranes possess the noticeable asymmetry of the current–voltage curve (CVC) under changing their orientation towards the applied electric field, despite the absence of asymmetry of diffusion permeability. These phenomena were explained in the frame of the “fine-porous model” expanded for bi-layer membranes. A special procedure to calculate the real values of the diffusion layers thickness and the limiting current density was proposed. Due to asymmetry effects of the current voltage curves of bi-layer hybrid membranes on the base of MF-4SC, halloysite nanotubes and platinum nanoparticles, it is prospective to assemble membrane switches (membrane relays or diodes) with predictable transport properties, founded upon the theory developed here.

Au-Ag and Pt-Ag bimetallic nanoparticles@halloysite nanotubes: morphological modulation, improvement of thermal stability and catalytic performance

In this study, Au-Ag and Pt-Ag bimetallic nanocages were loaded on natural halloysite nanotubes (HNTs) via galvanic exchange based on Ag@HNT. By changing the ratio of Au to Ag or Pt to Ag in exchange processes, Au-Ag@HNT and Pt-Ag@HNT with different nanostructures were generated. Both Au-Ag@HNT and Pt-Ag@HNT systems showed significantly improved efficiency as peroxidase-like catalysts in the oxidation of o-phenylenediamine compared with monometallic Au@HNT and Pt@HNT, although inert Ag is dominant in the composition of both Au-Ag and Pt-Ag nanocages. On the other hand, loading on HNTs enhanced the thermal stability for every system, whether monometallic Ag nanoparticles, bimetallic Au-Ag or Pt-Ag nanocages. Ag@HNT sustained thermal treatment at 400 °C in nitrogen with improved catalytic performance, while Au-Ag@HNT and Pt-Ag@HNT maintained or even had slightly enhanced catalytic efficiency after thermal treatment at 200 °C in nitrogen. This study demonstrated that natural halloysite nanotubes are a good support for various metallic nanoparticles, improving their catalytic efficiency and thermal stability.

Core-shell nanoarchitecture: Schiff-base assisted synthesis of ruthenium in clay nanotubes

Natural halloysite clay nanotubes were used as a template for clay/Ru core-shell nanostructure synthesis. Ru-nanoparticles were produced via a ligand-assisted metal ion intercalation technique. Schiff bases formed from different organic compounds proved to be effective ligands for the metal interfacial complexation which then was converted to Ru particles. This produces a high amount of intercalated metal nanoparticles in the tube’s interior with more that 90% of the sample loaded with noble metal. Depending on the selection of organic linkers, we filled the tube’s lumen with 2 or 3.5-nm diameter Ru particles, or even larger metal clusters. Produced nanocomposites are very efficient in reactions of hydrogenation of aromatic compounds, as tested for phenol and cresols hydrogenation.

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. The obtained halloysite-nanoparticle composites can be employed as advanced catalysts, ion-conducting membrane modifiers, inorganic pigments, and optical markers for biomedical studies. Here, we discuss the possibilities to synthesize halloysite decorated with metal, metal chalcogenide, and carbon nanoparticles, and to use these materials in various fields, especially in catalysis and petroleum refinery.

Layered double hydroxide anchored ionic liquids as amphiphilic heterogeneous catalysts for the Knoevenagel condensation reaction

In this paper, three solid base catalysts of LDH-IL-Cn (n = 4, 8, 12) were synthesized by adopting an exfoliation/assembly approach. The as-prepared catalyst showed excellent activity and selectivity for the Knoevenagel reaction in aqueous solution.

Preparation and Enhanced Catalytic Hydrogenation Activity of Sb/Palygorskite (PAL) Nanoparticles

A Sb/palygorskite (PAL) composite was synthesized by a facile solvothermal process and applied in catalytic hydrogenation of p-nitrophenol for the first time. It was found that the Sb nanoparticles with the sizes of 2-5 nm were well dispersed on the fiber of PAL, while partial aggregated Sb nanoparticles with sizes smaller than 200 nm were also loaded on the PAL. The Sb/PAL composite with 9.7% Sb mass amounts showed outstanding catalytic performance by raising the p-nitrophenol conversion rate to 88.3% within 5 min, which was attributed to the synergistical effect of Sb and PAL nanoparticles facilitating the adsorption and catalytic hydrogenation of p-nitrophenol.