Functionalized halloysite multivalent glycocluster as a new drug delivery system

Halloysite-TiO2 Nanocomposites for Water Treatment: A Review

Halloysite nanotubes (HNTs) are clay minerals with a tubular structure that can be used for many different applications in place of carbon nanotubes. Indeed, HNTs display low/non-toxicity, are biocompatible, and can be easily prepared. Moreover, the aluminum and silica groups present on HNTs' inner and outer surfaces facilitate the interaction with various functional agents, such as alkalis, organosilanes, polymers, surfactants, and nanomaterials. This allows the deposition of different materials, for instance, metal and non-metal oxides, on different substrate types. This review article first briefly presents HNTs' general structure and the various applications described in the last 20 years (e.g., drug delivery, medical implants, and energy storage). Then, it discusses in detail HNT applications for water purification (inorganic and organic pollutants). It focuses particularly on HNT-TiO₂ composites that are considered very promising photocatalysts due to their high specific surface area and adsorption capacity, large pore volume, good stability, and mechanical features.

Functionalized Halloysite Nanotubes as Potential Drug Carriers

The aim of the work was to examine the possibility of using modified halloysite nanotubes as a gentamicin carrier and to determine the usefulness of the modification in terms of the effect on the amount of the drug attached, its release time, but also on the biocidal properties of the carriers. In order to fully examine the halloysite in terms of the possibility of gentamicin incorporating, a number of modifications of the native halloysite were carried out prior to gentamicin intercalation with the use of sodium alkali, sulfuric and phosphoric acids, curcumin and the process of delamination of nanotubes (expanded halloysite) with ammonium persulfate in sulfuric acid. Gentamicin was added to unmodified and modified halloysite in an amount corresponding to the cation exchange capacity of pure halloysite from the Polish Dunino deposit, which was the reference sample for all modified carriers. The obtained materials were tested to determine the effect of surface modification and their interaction with the introduced antibiotic on the biological activity of the carrier, kinetics of drug release, as well as on the antibacterial activity against Escherichia coli Gram-negative bacteria (reference strain). For all materials, structural changes were examined using infrared spectroscopy (FTIR) and X-ray diffraction (XRD); thermal differential scanning calorimetry with thermogravimetric analysis (DSC/TG) was performed as well. The samples were also observed for morphological changes after modification and drug activation by transmission electron microscopy (TEM). The conducted tests clearly show that all samples of halloysite intercalated with gentamicin showed high antibacterial activity, with the highest antibacterial activity for the sample modified with sodium hydroxide and intercalated with the drug. It was found that the type of halloysite surface modification has a significant effect on the amount of gentamicin intercalated and then released into the surrounding environment but does not significantly affect its ability to further influence drug release over time. The highest amount of drug released among all intercalated samples was recorded for halloysite modified with ammonium persulfate (real loading efficiency above 11%), for which high antibacterial activity was found after surface modification, before drug intercalation. It is also worth noting that intrinsic antibacterial activity was found for non-drug-intercalated materials after surface functionalization with phosphoric acid (V) and ammonium persulfate in the presence of sulfuric acid (V).

Magnetic Halloysite Nanotube-Based SERS Biosensor Enhanced with Au@Ag Core-Shell Nanotags for Bisphenol A Determination

Bisphenol A (BPA) has emerged as a contaminant of concern because long-term exposure may affect the human endocrine system. Herein, a novel aptamer sensor based on magnetic separation and surface-enhanced Raman scattering (SERS) is proposed for the extremely sensitive and specific detection of trace BPA. Moreover, the capture unit was prepared by immobilizing thiolated (SH)-BPA aptamer complementary DNA on AuNP-coated magnetic halloysite nanotubes (MNTs@AuNPs), and SH-BPA aptamer-modified Au@4-MBA@Ag core-shell SERS nanotags acted as signal units. By the complementary pairing of the BPA aptamer and the corresponding DNA, MNTs@AuNPs and Au@4-MBA@AgCS were linked together through hybridization-ligation, which acted as the SERS substrate. In the absence of BPA, the constructed aptamer sensor generated electromagnetic enhancement and plasmon coupling to improve the sensitivity of SERS substrates. Owing to the high affinity between BPA and the aptamer, the aptamer probe bound to BPA was separated from the capture unit by an externally-induced magnetic field. Thus, the Raman intensity of the MNTs@AuNP-Ag@AuCS core-satellite assemblies was negatively correlated with the BPA concentration. High sensitivity measurements of BPA might be performed by determining the decline in SERS signal strength together with concentration variations. The proposed aptasensor is a promising biosensing platform for BPA detection.

Halloysites modified polyethylene glycol diacrylate/thiolated chitosan double network hydrogel combined with BMP-2 for rat skull regeneration

Hydrogel serve as bone tissue engineering have lately received great attention for their good biocompatibility and structures similar to natural extracellular matrices. However, a single component polymer hydrogel is generally detrimental to cell adhesion due to the weaker mechanical properties, which limits their application considerably. In an effort to overcome this disadvantage, we adopt an unconventional dual network hydrogels consisting of the polyethylene glycol diacrylate (PEGDA) covalent network, a thiolated chitosan (TCS) ion crosslinking network and thiolated halloysites (T-HNTs) as reinforcing filler. In addition, bone morphogenetic protein-2 (BMP-2) was loaded into the prepared dual network (DN) hydrogel to improve the bone regeneration function of the DN hydrogel. The resulting PEGDA/TCS/T-HNTs hydrogels showed favourable mechanical property, higher crosslinking density, the lower swelling degree, excellent biocompatibility and cell adhesion ability. The histomorphometric and immunohistochemical analyses revealed the excellent bone regeneration ability for composite hydrogel after implant into rat skull defect. Thus, our results indicated that composite scaffold can be applied as a new bone regeneration biomaterial to be applied as a local drug delivery system with good bone induction performance.

Application of Halloysite Nanotubes in Cancer Therapy-A Review

Halloysite, a nanoclay characterized by a unique, tubular structure, with oppositely charged interior and exterior, suitable, nanometric-range size, high biocompatibility, and low cost, is recently gaining more and more interest as an important and versatile component of various biomaterials and delivery systems of biomedical relevance. One of the most recent, significant, and intensely studied fields in which halloysite nanotubes (HNTs) found diverse applications is cancer therapy. Even though this particular direction is mentioned in several more general reviews, it has never so far been discussed in detail. In our review, we offer an extended survey of the literature on that particular aspect of the biomedical application of HNTs. While historical perspective is also given, our paper is focused on the most recent developments in this field, including controlled delivery and release of anticancer agents and nucleic acids by HNT-based systems, targeting cancer cells using HNT as a carrier, and the capture and analysis of circulating tumor cells (CTCs) with nanostructured or magnetic HNT surfaces. The overview of the most up-to-date knowledge on the HNT interactions with cancer cells is also given.

Development of epimedin A complex drugs for treating the osteoporosis

Osteoporosis is the most common disease involving bone degeneration. As the age of the population increases, the prevalence of the disease is expected to rise. However, current treatment methods do not provide a desirable solution for the restoration of the function of degenerated bones in patients with osteoporosis. This led to emergence of controlled delivery systems to increase drug bioavailability and efficacy specifically at the bone regeneration. In this study, an epimedin A (EA) complex drug system was prepared by solution blending method. In vitro cell-based experiments showed that the EA complex drug could significantly promote the differentiation and proliferation of osteoblasts and increase the alkaline phosphatase activity, calcium nodule formation, and the expression of osteogenesis-related genes and proteins. In vivo experiments further demonstrated that this novel drugs remarkably enhanced bone regeneration. These results suggest that EA may be used for the treatment of osteoporosis.

Cyclodextrin-Based Functional Glyconanomaterials

Cyclodextrins (CDs) have long occupied a prominent position in most pharmaceutical laboratories as "off-the-shelve" tools to manipulate the pharmacokinetics of a broad range of active principles, due to their unique combination of biocompatibility and inclusion abilities. The development of precision chemical methods for their selective functionalization, in combination with "click" multiconjugation procedures, have further leveraged the nanoscaffold nature of these oligosaccharides, creating a direct link between the glyco and the nano worlds. CDs have greatly contributed to understand and exploit the interactions between multivalent glycodisplays and carbohydrate-binding proteins (lectins) and to improve the drug-loading and functional properties of nanomaterials through host-guest strategies. The whole range of capabilities can be enabled through self-assembly, template-assisted assembly or covalent connection of CD/glycan building blocks. This review discusses the advancements made in this field during the last decade and the amazing variety of functional glyconanomaterials empowered by the versatility of the CD component.

Nanocontainers for drug delivery systems: A review of Halloysite nanotubes and their properties

Halloysite nanotubes (HNTs) are known as inexpensive and available nanomaterials that are rich in functionality, environmentally benign, and also safe and easy to process. As well, good particle size (i.e. nanoscale) and perfect tubular microstructures of these materials make them to be used extensively as drug carriers. Also, the unique physical and chemical properties of their internal and external surfaces are the greatest priority for the drug encapsulation controlling and releasing. In this review, is tried to emphasis on the main properties of HNTs to manage and develop effective drug delivery tools in the biomedical and pharmaceutical fields.

Past, Present and Future Perspectives on Halloysite Clay Minerals

Halloysite nanotubes (HNTs), clay minerals belonging to the kaolin groups, are emerging nanomaterials which have attracted the attention of the scientific community due to their interesting features, such as low-cost, availability and biocompatibility. In addition, their large surface area and tubular structure have led to HNTs' application in different industrial purposes. This review reports a comprehensive overview of the historical background of HNT utilization in the last 20 years. In particular it will focus on the functionalization of the surfaces, both supramolecular and covalent, following applications in several fields, including biomedicine, environmental science and catalysis.

Kaolinite group minerals: Applications in cancer diagnosis and treatment

The clay minerals are characterized as important minerals due to their specific properties. One of the most important groups of the clay minerals is the kaolinite's group minerals due to their morphology, availability and range of potential applications. Halloysite and kaolinite are investigated here for their pharmaceutical applications and especially for their potential in cancer treatment. This review study is focusing on the potential applications of the kaolinite's group minerals in cancer diagnosis and monitoring, cancer treatment, the avoidance of metastasis, and the relief of cancer pains. Anticancer drug-loaded formulations based on these minerals show high potential for the treatment of various types of cancer as they have been shown to exhibit high anticancer activity in cancer cell lines and cancer animal models, high biocompatibility, low side effects, and high drug bioavailability.

Selective Antimicrobial Effects of Curcumin@Halloysite Nanoformulation: A Caenorhabditis elegans Study

Alterations in the normal gastrointestinal microbial community caused by unhealthy diet, environmental factors, and antibiotic overuse may severely affect human health and well-being. Novel antimicrobial drug formulations targeting pathogenic microflora while not affecting or even supporting symbiotic microflora are urgently needed. Here we report fabrication of a novel antimicrobial nanocontainer based on halloysite nanotubes loaded with curcumin and protected with a dextrin outer layer (HNTs+Curc/DX) and its effective use to suppress the overgrowth of pathogenic bacteria in Caenorhabditis elegans nematodes. Nanocontainers have been obtained using vacuum-facilitated loading of hydrophobic curcumin into halloysite lumens. We have applied UV-vis and infrared spectroscopy, thermogravimetry and microscopy to characterize the HNTs+Curc/DX nanocontainers. In experiments in vitro we found that HNTs+Curc/DX effectively suppressed the growth of Serratia marcescens cells, whereas Escherichia coli bacteria were not affected. We applied HNTs+Curc/DX nanocontainers to alleviate the S. marcescens infection in C. elegans nematodes in vivo. The nematodes ingest HNTs+Curc/DX at 4-6 ng per worm, which results in improvement of the nematodes' fertility and life expectancy. Remarkably, treatment of S. marcescens-infected nematodes with HNTs+Curc/DX nanocontainers completely restored the longevity, demonstrating the enhanced bioavailability of hydrophobic curcumin. We believe that our results reported here open new avenues for fabrication of effective antimicrobial nanoformulations based on hydrophobic drugs and clay nanotubes.

Fabrication and characterization of biocompatible pH responsive halloysite nanotubes grafted with sodium alginate for sustained release of phenytoin sodium

Schematic design of a new method for fabrication of biocompatible pH sensitive halloysite nanocomposites for controlled release of phenytoin sodium.

Organo-Clay Nanomaterials Based on Halloysite and Cyclodextrin as Carriers for Polyphenolic Compounds

Hybrid material based on halloysite covalently linked to a hyper-reticulated cyclodextrin network was investigated as a potential carrier for polyphenolic compounds. The absorption ability of the hybrid system was studied in different pH conditions as well as the kinetic release of curcumin, chosen as a drug model. A preliminary study was performed to assess the antioxidant capacity of the obtained carrier. The obtained results highlighted that the curcumin molecule can have sustained release from the carrier over the time, retaining its antioxidant properties due to the combination of two different host systems that give rise to an hyper-reticulated structure, allowing an increase in the drug loading and stabilization. Therefore, this work puts forward an efficient strategy to prepare organic-inorganic hybrids with three different cavities that could encapsulate two or more drug molecules with different physico-chemical properties.

The Use of Some Clay Minerals as Natural Resources for Drug Carrier Applications

The goal of modern research is to use environmentally preferable materials. In this context, clay minerals are emerging candidates for their bio- and ecocompatibility, low cost and natural availability. Clay minerals present different morphologies according to their layer arrangements. The use of clay minerals, especially in biomedical applications is known from ancient times and they are regaining attention in recent years. The most representative clay minerals are kaolinit, montmorillonite, sepiolites and halloysite. This review summarizes some clay minerals and their derivatives for application as nanocontainer for biologically active species.

Selective adsorption of oppositely charged PNIPAAM on halloysite surfaces: a route to thermo-responsive nanocarriers

Halloysite nanotubes were functionalized with stimuli-responsive macromolecules to generate smart nanohybrids. Poly(N-isopropylacrylamide)-co-methacrylic acid (PNIPAAM-co-MA) was selectively adsorbed into halloysite lumen by exploiting electrostatic interactions. Amine-terminated PNIPAAM polymer was also investigated that selectively interacts with the outer surface of the nanotubes. The adsorption site has a profound effect on the thermodynamic behavior and therefore temperature responsive features of the hybrid material. The drug release kinetics was investigated by using diclofenac as a non-steroidal anti-inflammatory drug model. The release kinetics depends on the nanoarchitecture of the PNIPAAM/halloysite based material. In particular, diclofenac release was slowed down above the LCST for PNIPAAM-co-MA/halloysite. Opposite trends occurred for halloysite functionalized with PNIPAAM at the outer surface. This work represents a further step toward the opportunity to extend and control the delivery conditions of active species, which represent a key point in technological applications.

Halloysite nanotubes in analytical sciences and in drug delivery: A review

Halloysite (HNT) is a natural inorganic mineral that has many applications in manufacturing. This review (with 192 references) covers (a) the chemical properties of halloysites, (b) the effects of alkali and acid etching on the loading capacity and the release behavior of halloysites, (c) the use of halloysite nanotubes in analytical sciences and drug delivery, and (d) recent trends in the preparation of magnetic HNTs. Synthetic methods such as co-precipitation, thermal decomposition, and solvothermal method are discussed, with emphasis on optimal magnetization. In the analytical field, recent advancements are summarized in terms of applications of HNT-nanocomposites for extraction and detection of heavy metal ions, dyes, organic pollutants, and biomolecules. The review also covers methods for synthesizing molecularly imprinted polymer-modified HNTs and magnetic HNTs. With respect to drug delivery, the toxicity, techniques for drug loading and the various classes of drug-halloysite nanocomposites are discussed. This review gives a general insight on the utilization of HNT in analytical determination and drug delivery systems which may be useful for researchers to generate new ideas. Graphical abstract Schematic presentation of the structure of halloysite nanotubes, selected examples of modifications and functionalization, and represetative field of applications.

Halloysite clay nanotubes for life sciences applications: From drug encapsulation to bioscaffold

Natural forming clay halloysite is an emerging nanomaterial carrier for sustained drug delivery. These 50 nm diameter aluminosilicate tubes, with inner - alumina and outer - silica surface layers, can be loaded with 10-30 wt% of drug molecules, DNA and enzymes. The opposite charge of the inner and outer halloysite surface allow for selective drug adsorption inside or outside the clay nanotubes. The drug loaded halloysite enhanced the zeta potential of minus 50-60 mV allowing for stable aqueous nanocolloids. Halloysite nanoformulations provide an extended 10-20 h release profile, and may be functionalized (e.g., clogging tubes' end with polymers extending release time to 1-2 weeks or allowing for triggered release), which renders these clay nanostructures as promising controlled delivery systems. Recent studies demonstrate the potential of abundantly available halloysite clay nanotubes for life science applications, from drug delivery via oral or topical administration, to tissue scaffolds and regenerative medicine, while assessing their cellular internalization, stability, biosafety and biocompatibility are featured. The benefits and limitations of halloysite clay nanotubes are discussed, as well as the directions for future developments.

Chemical modification of halloysite nanotubes for controlled loading and release

Clay minerals have been used for medical purposes from ancient times. Among them, the halloysite nanotube, an aluminosilicate of the kaolin group, is an emerging nanomaterial which possesses peculiar chemical characteristics. By means of suitable modifications, such as supramolecular functionalization or covalent modifications, it is possible to obtain novel nanomaterials with tunable properties for several applications. In this context the covalent grafting of suitable organic moieties on the external surface or in the halloysite lumen has been exploited to improve the loading and release of several biologically active molecules. The resulting hybrid nanomaterials have been applied as drug carrier and delivery systems, as fillers for hydrogels, in tissue regeneration and in the gene delivery field. Furthermore the loading and release of specific molecules have been also investigated for environmental purposes. This review summarizes the main developments in the halloysite modifications in the last 20 years with a particular attention to the development in the past two years.

Halloysite Nanotube-Modified Plasmonic Interface for Highly Sensitive Refractive Index Sensing

We propose and demonstrate a novel strategy to modify the plasmonic interface by using a thin layer of halloysite nanotubes (HNTs). The modified surface plasmon resonance (SPR) sensor achieves a greatly improved sensitivity because the large surface area and high refractive index of the HNTs layer significantly increase the probing electric field intensity and hence the measurement sensitivity. More significantly, the thickness of the HNTs layer can be tailored by spraying different concentrations of HNTs ethanol suspension. The proposed sensors show significant superiority in terms of the highest sensitivity (10431 nm/RIU) and the enhancement fold (5.6-folds) over those reported previously. Additionally, the proposed approach is a chemical-free and environment-friendly modification method for the sensor interface, without additional chemical or biological amplification steps (no toxic solvents are used). These unique features make the proposed HNTs-SPR biosensor a simple, biocompatible, and low-cost platform for the trace-level detection of biochemical species in a rapid, sensitive, and nondestructive manner.

Pd nanoparticles immobilized on halloysite decorated with a cyclodextrin modified melamine-based polymer: a promising heterogeneous catalyst for hydrogenation of nitroarenes

For the first time, a hybrid system composed of halloysite (Hal) and a cyclodextrin modified melamine-based polymer is developed and employed for immobilization of Pd(0) nanoparticles.

Halloysite nanotubes as carriers of vancomycin in alginate-based wound dressing

The influence of an inorganic support - halloysite nanotubes - on the release rate and biological activity of the antibiotic encapsulated in alginate-based dressings was studied. The halloysite samples were loaded with approx. 10 wt.% of the antibiotic and then encapsulated in Alginate and Gelatin/Alginate gels. The material functionalized with aliphatic amine significantly extended the release of vancomycin from alginate-based gels as compared to that achieved when silica was used. After 24 h, the released amounts of the antibiotic immobilized at silica reached 70%, while for the drug immobilized at halloysite the released amount of vancomycin reached 44% for Alginate discs. The addition of gelatin resulted in even more prolonged sustained release of the drug. The antibiotic was released from the system with a double barrier with Higuchi kinetic model and Fickian diffusion mechanism. Only the immobilized drug encapsulated in Alginate gel demonstrated very good antimicrobial activity against various bacteria. The inhibition zones were greater than those of the standard discs for the staphylococci and enterococci bacteria tested. The addition of gelatin adversely affected the biological activity of the system. The inhibition zones were smaller than those of the reference samples. A reduction in the drug dose by half had no significant effect on changing the release rate and microbiological activity. The in vivo toxicity studies of the material with immobilized drug were carried out with Acutodesmus acuminatus and Daphnia magna. The material studied had no effect on the living organisms used in the bioassays. The proposed system with a double barrier demonstrated high storage stability.

Clay-based drug-delivery systems: what does the future hold?

Clays for drug delivery have been used from ancient time due to the large availability of clay minerals and their unprecedented properties. The empirical use of nanoclays from the past is converted in a stimulating scientific task aimed at building up nanoarchitectonic vehicles for drug delivery in a targeted and stimuli-responsive fashion. Here the historical aspects are discussed; next the modern examples of applications of different clay-based materials are discussed. A special focus is given to halloysite clay nanotubes, which are an emerging and very promising nanomaterial for drug-delivery purposes due to its special morphology and unique chemical properties. Advantages and limitations of these natural nanomaterials are critically discussed pointing out the future perspectives and directions for further research.

Self-Assembling Halloysite Nanotubes into Concentric Ring Patterns in a Sphere-on-Flat Geometry

Highly ordered and concentric ring patterns consisting of halloysite nanotubes (HNTs) with hierarchical cholesteric architectures are prepared by evaporation-induced self-assembly in a sphere-on-flat geometry. The structure and properties of HNTs are investigated. HNTs show a perfect tubular morphology on the nanoscale with high dispersion stability in water. Upon drying the HNTs aqueous suspension in a sphere-on-flat confined space, regular concentric HNTs rings are formed on the substrate via a self-assembly process. The widths of the inner and outer rings and the spacing between the adjacent rings increase with an increase in the concentration of the HNTs suspension. The highly ordered and concentric HNTs rings show a pronounced Maltese cross-like pattern under crossed polarizers, which suggests the formation of hierarchical cholesteric architectures. Scanning electron microscopy and atomic force microscopy observations show a disclination alignment of HNTs in the ring strips, especially with a high concentration of the HNTs suspension. The patterned rough surfaces of the HNTs show low cytotoxicity and can be used as a cell-supporting scaffold. The HNTs rings can guide the growth and orientation of C2C12 myoblast cells perpendicular to the rings. This work provides a simple, repeatable, mild, and high-efficiency method for obtaining HNTs with hierarchical architectures, which show potential for a large variety of applications, for example, in vascular grafts and skin regeneration.

Improved bioavailability of curcumin in liposomes prepared using a pH-driven, organic solvent-free, easily scalable process

pH-driven method, an organic solvent-free and easily scale-upable method, was firstly utilized to prepared curcumin-loaded liposomes.

Covalently modified halloysite clay nanotubes: synthesis, properties, biological and medical applications

Halloysite (HNT) is a promising natural nanosized tubular clay mineral that has many important uses in different industrial fields.

Ecotoxicity of halloysite nanotube-supported palladium nanoparticles in Raphanus sativus L

Halloysite nanotubes (HNTs) are natural nanomaterials that are biocompatible and available in large amounts at low prices. They are emerging nanomaterials with appealing properties for applications like support for metal nanoparticles (NPs). The potential environmental impacts of NPs can be understood in terms of phytotoxicity. Current research has been focusing on HNT applications in cell or animal models, while their use in plants is limited so their ecotoxicological impact is poorly documented. To date there are no studies on the phytotoxic effects of functionalized halloysites (functionalized-HNTs). To develop a quantitative risk assessment model for predicting the potential impact of HNT-supported palladium nanoparticles (HNT-PdNPs) on plant life, an investigation was undertaken to explore their effects on seed germination, seedling development, and mitotic division in root tip cells of 2 lots of Raphanus sativus L. with different vigor. The results showed that exposure to 1500 mg/L of HNTs, functionalized-HNTs, and HNT-PdNPs had no significant influence on germination, seedling development, xylem differentiation, or mitotic index in both lots. Cytogenetic analyses revealed that treatments with functionalized-HNT significantly increased the number of aberrations in low-vigor seeds. These results suggest that low-vigor seeds represent a model for a stress test that would be useful to monitor the effects of NPs. Moreover the present study offers scientific evidence for the use of halloysite for environmental purposes, supporting the biological safety of HNT-PdNPs. Environ Toxicol Chem 2016;35:2503-2510. © 2016 SETAC.

Stripe-like Clay Nanotubes Patterns in Glass Capillary Tubes for Capture of Tumor Cells

Here, we used capillary tubes to evaporate an aqueous dispersion of halloysite nanotubes (HNTs) in a controlled manner to prepare a patterned surface with ordered alignment of the nanotubes . Sodium polystyrenesulfonate (PSS) was added to improve the surface charges of the tubes. An increased negative charge of HNTs is realized by PSS coating (from -26.1 mV to -52.2 mV). When the HNTs aqueous dispersion concentration is higher than 10%, liquid crystal phenomenon of the dispersion is found. A typical shear flow behavior and decreased viscosity upon shear is found when HNTs dispersions with concentrations higher than 10%. Upon drying the HNTs aqueous dispersion in capillary tubes, a regular pattern is formed in the wall of the tube. The width and spacing of the bands increase with HNTs dispersion concentration and decrease with the drying temperature for a given initial concentration. Morphology results show that an ordered alignment of HNTs is found especially for the sample of 10%. The patterned surface can be used as a model for preparing PDMS molding with regular micro-/nanostructure. Also, the HNTs rough surfaces can provide much higher tumor cell capture efficiency compared to blank glass surfaces. The HNTs ordered surfaces provide promising application for biomedical areas such as biosensors.

Liquid crystal self-assembly of halloysite nanotubes in ionic liquids: a novel soft nanocomposite ionogel electrolyte with high anisotropic ionic conductivity and thermal stability

We report a novel class of liquid crystalline (LC) nanohybrid ionogels fabricated via self-assembly of natural halloysite nanotubes (HNTs) in ionic liquids (ILs). The obtained ionogels are very stable and nonvolatile and show LC phases over a wide temperature range. Remarkably, the nanocomposite ionogels exhibit high anisotropic ionic conductivity after shear, and their room temperature ionic conductivity can reach 3.8 × 10(-3) S cm(-1) for aligned nanotubes perpendicular to the electrode even when the HNTs content increases to 40 wt%, which is 380 times higher than that obtained for aligned nanotubes parallel to the electrode, which is 1.0 × 10(-5) S cm(-1). Crucially, the obtained LC nanocomposite ionogels have very high thermal stability, which can sustain 400 °C thermal treatment. The findings will promote the development of novel nanocomposite ionogel electrolytes with faster ion transport and larger anisotropic conductivity.

Chemical and pharmaceutical evaluation of the relationship between triazole linkers and pore size on cyclodextrin–calixarene nanosponges used as carriers for natural drugs

Nanosponges based nanocarriers with three different cavities were used to encapsulate and release bioactive compounds.

A novel aminoclay–curcumin hybrid for enhanced chemotherapy

“One-pot” synthesis is developed to fabricate the AC–Cur hybrid with high bioavailability.

Novel drug delivery nanosystems based on out-inside bifunctionalized mesoporous silica yolk–shell magnetic nanostars used as nanocarriers for curcumin

Bifunctionalized yolk–shell magnetic mesoporous silica is used as a curcumin nanocarrier with magnetic response and increased cellular uptake.

Dual drug-loaded halloysite hybrid-based glycocluster for sustained release of hydrophobic molecules

A dual drug-loaded HNT–CD glycocluster delivery system based on halloysite nanotubes and carbohydrate functionalized cyclodextrin for delivery of natural drugs was developed.

Functionalized halloysite nanotube by chitosan grafting for drug delivery of curcumin to achieve enhanced anticancer efficacy

A new HNTs-based drug delivery system to improve the bioavailability of curcumin for cancer therapy is proposed.

Design of PNIPAAM covalently grafted on halloysite nanotubes as a support for metal-based catalysts

A thermo-responsive polymer (PNIPAAM) was covalently grafted on the external surface of halloysite nanotubes and used as support for palladium nanoparticles for application as catalyst in Suzuki cross coupling in water under microwave irradiation.

Molecular recognition of aromatic carboxylic acids by hydroxypropyl-γ-cyclodextrin: experimental and theoretical evidence

Inclusion complex formation of hydroxypropyl-γ-cyclodextrin with benzoic, nicotinic and isomeric aminobenzoic acids in water was studied by calorimetry, ¹H NMR, densimetry and molecular modeling.