HNT-Cellulose based Nano-Composite and Applications

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.

Epoxy resins are widely used in various industrial fields due to their low cost, good workability, heat resistance, and good mechanical strength. However, they suffer from brittleness, an issue that must be addressed for further applications. To solve this problem, additional fillers are needed to improve the mechanical and thermal properties of the resins; zirconia is one such filler. However, it has been reported that aggregation may occur in the epoxy composites as the amount of zirconia increases, preventing enhancement of the mechanical strength of the epoxy composites. Herein, to reduce the aggregation, zirconia was well dispersed on halloysite nanotubes (HNTs), which have high thermal and mechanical strength, by a conventional wet impregnation method. The HNTs were impregnated with zirconia at different loadings using zirconyl chloride octahydrate as a precursor. The mechanical and thermal strengths of the epoxy composites with these fillers were investigated. The zirconia-impregnated HNTs (Zr/HNT) were characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and tunneling electron microscopy (TEM). The hardening conditions of the epoxy composites were analyzed by differential scanning calorimetry (DSC). The thermal strength of the epoxy composites was studied by thermomechanical analysis (TMA) and micro-calorimetry and the mechanical strength of the epoxy composites (flexural strength and tensile strength) was studied by using a universal testing machine (UTM). The mechanical and thermal strengths of the epoxy composites with Zr/HNT were improved compared to those of the epoxy composite with HNT, and also increased as the zirconia loading on HNT increased.

Nanotechnology is a field that is growing quickly and has many uses in science, industry, the environment, energy, and other areas. Halloysite is a common, economically viable nanomaterial composed of clay. Widely employed in the biomedical area are elongated tubes of halloysite particles in a variety of shapes and dimensions, including shorter tubules, spheroidal and platy clays (caolin and mountain morillonite). This research investigates the utilisation of halloysite nanotube (HNT) composites in wound healing and drug-carrying vehicles. The review indicates that tubular HNTs are suitable for wound healing due to their high mechanical strength, biocompatibility, and hemostasis. It was looked into whether HNTs could be used as biocompatible nanocontainers for the controlled and gradual release of antiseptals. Nanotubes have also been found in many studies looking for ways to treat antibacterial and antiseptic wounds. When HNT is added to porous and flexible sponges, it makes the elastic module more flexible, stronger, and tighter. Keywords: Halloysite nanotube, drug delivery, mechanical strength, biocompatible, wound healing .

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.

Modified natural halloysite nanotube solely employed as an efficient and low-cost solid acid catalyst for alpha-arylstyrenes production via direct alkenylation

Medical mineralogy explores the interactions between natural minerals and living organisms such as cells, tissues, and organs and develops therapeutic and diagnostic applications in drug delivery, medical devices, and healthcare materials. Many minerals (especially clays) have been recognized for pharmacological activities and therapeutic potential. Halloysite clay (Chinese medicine name: Chishizhi), manifested as one-dimensional aluminum silicate nanotubes (halloysite nanotubes, HNTs), has gained applications in hemostasis, wound repair, gastrointestinal diseases, tissue engineering, detection and sensing, cosmetics, and daily chemicals formulations. Various biomedical applications of HNTs are derived from hollow tubular structures, high mechanical strength, good biocompatibility, bioactivity, and unique surface characteristics. This natural nanomaterial is safe, abundantly available, and may be processed with environmentally safe green chemistry methods. This review describes the structure and physicochemical properties of HNTs relative to bioactivity. We discuss surface area, porosity and surface defects, hydrophilicity, heterogeneity and charge of external and internal surfaces, as well as biosafety. The paper provides comprehensive guidance for the development of this tubule nanoclay and its advanced biomedical applications for clinical diagnosis and therapy.

Increasing health concerns regarding the use of plasticware have led to the development of ecofriendly biodegradable packaging film from natural polymer and food additives. In the present study, basil essential oil (BEO) loaded halloysite nanotubes (HNTs) composite films were synthesized using a solution casting method. The effects of BEO and nanotube concentration on the mechanical, physical, structural, barrier, and antioxidant properties of films were evaluated. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) demonstrated well-dispersed HNTs and BEO in tailored composite films. The addition of BEO in Chitosan (Ch) film caused darkening of the film color; furthermore, the incorporation of HNTs in varied concentrations increased opaqueness in Ch/BEO film. The Ch/BEO film, upon adding HNTs 5-30 wt%, exhibited a corresponding increase in the film thickness (0.108-0.135 mm) when compared with the Ch/BEO film alone (0.081 mm). The BEO-loaded HNTs composite films displayed reduced moisture content and characteristic barrier and UV properties. The Ch/BEO film with 15 wt% HNTs was found to have enhanced antioxidant activity. The Ch/BEO/HNTs composite also managed to prevent broccoli florets from losing weight and firmness during storage. The enhanced barrier and antioxidant qualities of the nanocomposite film suggest its potential application in the food processing and packaging sector. This is the first ever report on the fabrication of nanocomposite film using BEO and HNTs for food packaging. The low production cost and ecofriendly approach make the film acceptable for further research and commercialization thereafter.

Halloysite nanotubes (HNTs) are natural clay minerals with a tubular structure. They have attracted considerable attention as a potential nanocontainer due to their abundance, biocompatibility and nontoxicity. In this study, HNTs were handled with H₂SO₄ at 70 °C. The morphology and structure of these acid-treated and original HNTs were investigated by scanning electron microscopy (SEM), energy dispersion spectrum (EDS), transmission electron microscope (TEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR), and their specific surface area was determined by automatic gas adsorption analyzer. The loading efficiency and release behavior of acid-treated HNTs for 2-Mercaptobenzothiazole (MBT) were investigated by UV-vis spectrophotometer. Results show that acid-treated HNTs retained their tubular structure, but their internal diameter expanded by 35-37 nm after 32 h of acid treatment. After 72 h of acid treatment, HNTs can be transferred into amorphous silica nanotubes. Moreover, the specific surface area of these HNTs samples initially increased with the increase in acid treatment time but then started to decrease after 32 h. The specific surface area of acid-treated HNTs at 32 h can reach 251.6 m₂/g, which was much higher than that for untreated HNTs (55.3 m₂/g). In addition, the loading capacity of acid-treated HNTs can reach 32.1% for HNTs-32, which is about three times higher than that of original HNTs. The acid treatment has slight effect on the release behavior.

Clay minerals are considered one of the materials of the 20th century for their peculiar physico-chemical features. Among them, halloysite nanotubes (HNTs) are an emerging nanomaterial with a particular tubular structure that makes them a low cost and valuable alternative to the most common carbon nanotubes. Due to their tubular morphology, HNTs are employed in several fields acting as nanocontainers for different compounds for applications in drug carrier and delivery fields, catalysis, and as filler for polymeric matrices. The modification of HNTs’ surfaces allows to the synthesis of different nanoarchitectures that can improve the mechanical and thermal performance of polymer as well as they can enhance the use for the loading and release of chemicals. In this review, we summarize our recent results on halloysite functionalization, both supramolecular and covalent, and the application aforementioned fields.

Halloysite nanotubes (HNTs), the naturally formed mineral clays with hollow tubular structures, have found promising applications as nanocarriers for drug delivery systems due to their biocompatibility and nontoxicity. By modifying the lumen of HNT, drug delivery of various types of sensitive and low-dissolution drugs could be enhanced. This study presents a comparison of the properties of modified HNTs containing an organic modifier (Sodium Laureth Sulfate, SLES) and an inorganic modifier (Sodium Thiosulfate, STS) as carriers of a slightly water-soluble drug, aspirin. HNTs modified by STS showed higher negative zeta potential than those modified by SLES, indicating that STS-modified HNTs are relatively more stable. The negative zeta potential of STS-modified HNT however decreased upon aspirin loading while that of SLES-modified HNT increased, implying that aspirin interacts with the modifiers differently. In terms of drug release, both modified HNTs showed an improved aspirin release rate compared with pure HNT. Moreover, the STS-modified HNT showed a higher aspirin release (21.5%) in the first hour but the SLES-modified HNT showed the highest cumulative release of 62.5% after 6 hours. These results therefore show that the developed modified HNTs improve the release of aspirin and demonstrate how the nature of the modifier (organic or inorganic) on the HNT lumen affects the behaviour of the drug release of aspirin. This also gives an avenue for modulating drug release based on certain requirements such as time and quantity of drug released.

With the development of material design theories and synthesis technologies, clay-based composite materials have been controllably prepared and successfully applied in many fields, such as biomedicine, the automotive industry, petrochemical engineering, and wastewater treatment. To date, for the preparation of clay-based composite materials, the physical and chemical properties of clay must be fully considered, including the chemical composition, crystal structure, particle size, morphology, and surface charge. Halloysite, which has a tubular crystal structure, is a curly layered aluminosilicate clay with abundant reserves and a low price for constructing composite materials. The inner and outer surfaces of halloysite nanotubes are composed of Al−OH octahedrons and Si−O tetrahedrons, respectively, which ionize in opposite ways in water, resulting in opposite charges on the inner and outer surfaces. Therefore, the selective modification of halloysite can be achieved by chemical or electrostatic adsorption of the required chemical reagent. Additionally, the modified halloysite nanotubes can be used in catalysis and the loading and release of drug molecules. Moreover, because of its nanotube structure, the halloysite can be used to construct rough structures in micro- or nano-scale. By incorporation with low-surface-energy materials, the hydrophobic halloysite-based composite materials can be prepared for self-cleaning and oil-water separation. In this review, we introduced the rational design and preparation strategies of the hydrophobic halloysite-based composite materials. Then, we summarized the applications of these prepared composite materials in oil-water separation, hydrophobic self-cleaning coating, and the loading and sustained release of drug molecules. In addition, the related mechanisms and strategies for performance improvement were systematically discussed. Finally, the existing challenges and promising future directions in this research field were proposed. The halloysite-based composite materials have enhanced properties that are highly required, including enhanced mechanical and adhesive strength, excellent scratch and wear resistance, self-healing, and higher compatibility with living organisms. We believe fruitful promising results can be achieved in this field with more effort.

In this study, the halloysite nanotubes (HNT) were incorporated into chitosan (CS) to prepare CS/HNT composite film by solution‐casting method. Different HNT contents were studied in relation to the morphological, optical, mechanical, barrier and thermal properties of CS/HNT composite films. After incorporation of HNT, the CS/HNT composite films showed improvement in UV light shielding, barrier against water vapor and oxygen, mechanical strength and thermal stability as well as achievement of ethylene scavenging property. Especially, when 5 wt% HNT were added, more homogenous distribution of HNT in CS matrix was observed by SEM, resulting in 169.9% increase in tensile strength, 52.94% decline in oxygen permeability and 4.07 times enhancement in the ethylene scavenging capacity at 100 kPa pressure compared with pure CS film. Moreover, the obtained film with 5 wt% HNT effectively maintained the freshness of bananas and cherry tomatoes under ambient conditions. This study demonstrated that the CS/HNT composite films could be used as active food packaging material to extend the shelf‐life of fresh fruits and vegetables.

Polylactic acid (PLA) has a long history in medical applications. Reinforced PLA has the potential to be used in the medical applications that require high mechanical strength such as coronary stents and bone fixation devices. Halloysite nanotube (HNT) has received considerable attention recently due to its tubular structure, high aspect ratio, high mechanical strength, thermal stability, biocompatibility and sustained drug releasing properties. Halloysite has been investigated in compounding with many polymers. However, the research in compounding halloysite with biodegradable materials for use in biological applications is sparse. In this study various weight fractions of HNT was compounded with the biodegradable polymer PLA using a melt compounding method. Tensile test, Fourier infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), contact angle test, scanning electron microscopy (SEM), void content and thermogravimetric analysis (TGA) were carried out to study the PLA/HNT composite. Tensile test results indicated that Young's modulus and stiffness of PLA were enhanced with the addition of HNT; FTIR spectra showed the interaction between the PLA and HNT; whereas contact angle measurements indicated that the wettability of the PLA/HNT composite was not affected by the addition of HNT. However, the thermal stability of PLA was adversely effected by the addition of HNT which may be related to the presence of voids between the polymer and matrix. Nevertheless, the reinforced PLA/HNT composite, which maintains the surface characteristics, may prove beneficial for use in biological applications. POLYM. COMPOS., 38:2166–2173, 2017. © 2015 Society of Plastics Engineers

Designing a smart polyurethane anti-corrosion coating loaded with APTES/IMZ modified halloysite nanotubes

Augmentin loaded functionalized halloysite nanotubes: A sustainable emerging nanocarriers for biomedical applications