Search Results (249)

Naturally occurring halloysite nanotubes (HNTs), a clay mineral characterized by a unique dual-charge architecture, offer a promising strategy for enhancing the performance of composite polymer electrolyte (CPE). In this work, HNTs are introduced as a low-cost, functional filler to simultaneously address two key limitations of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)-based CPE: low ionic conductivity and inadequate lithium-ion transference number. The negatively charged outer surface of HNTs facilitates Li⁺ transport, while the positively charged inner lumen confines anions such as TFSI⁻. Controlled acid etching (6 M HCl, 12 h) further optimizes this structure by removing surface impurities and enlarging the lumen, thereby enhancing both charge-directed ion transport pathways. The resulting HNT-modified CPE achieves a high ionic conductivity of 6.1 × 10⁻⁴ S⋅cm⁻¹ and a Li⁺ transference number of 0.73. When assembled into Li||CPE||LiFePO₄ cells, the electrolyte enables stable cycling over 300 cycles at 0.2C, retains 119.2 mAh/g at 2C, and delivers 85.7 mAh/g even at 5C, demonstrating excellent cycling stability and rate capability. This study reveals the potential of mineral-derived nanomaterials, with their inherent structural and physicochemical properties, to serve as key functional components in high-performance batteries. Full article

Unlocking the potential of polymer blends requires innovative strategies that transcend simple mixing. This study presents a novel approach by creating hybrid blends of epoxy and structurally compatible in situ synthesized epoxy acrylate (vinyl ester) resins, further reinforced with halloysite nanotubes (HNTs). We went beyond simple blending by synthesizing the epoxy acrylate (EA) component from the base epoxy resin, ensuring molecular-level compatibility. The epoxy acrylate was successfully synthesized via a ring-opening reaction, as confirmed by FTIR and ¹H-NMR. A series of blends at varying weight ratios of epoxy/epoxy acrylate (75/25, 50/50, and 25/75) was prepared and optimized using dynamic mechanical analysis (DMA) for the best viscoelastic performance and subsequently reinforced with 2 wt% HNTs. Our findings reveal that this unique approach fosters highly interpenetrated polymer networks (IPNs), as evidenced by thermal and viscoelastic behavior. The hybrid epoxy nanocomposite with a 75/25 blend ratio exhibits a superior balance of properties, demonstrating a synergistic enhancement in both thermal and thermomechanical properties compared to the neat epoxy and epoxy acrylate networks. The optimized hybrid epoxy composite exhibits a 147% increase in storage modulus (E′) and a 180% increase in loss modulus (E″) over the neat epoxy composite while enhancing thermal stability. This study not only presents HNT-reinforced epoxy/epoxy acrylate as a new family of robust hybrid nanocomposites but also provides a fundamental blueprint for compatibilizing and reinforcing thermoset blends for advanced applications. Full article

Polyethylene terephthalate (PET) has become the predominant material for single-use packaging owing to its cost and performance advantages. However, massive post-consumer waste leads to environmental concerns, and recycled PET from thermomechanical processing followed by chain extension often suffers from low toughness and poor processability, restricting its use to low-value applications. In this study, halloysite nanotubes (HNTs) and ethylene–methyl acrylate–glycidyl methacrylate random terpolymer (E-MA-GMA) were melt-blended with recycled PET to examine their synergistic modification effects. The DSC results show that HNTs retain a nucleating effect on recycled PET even with the co-addition of E-MA-GMA, albeit with a substantial reduction compared with their effect when used alone. Nevertheless, rheological measurements indicate that the combined introduction of E-MA-GMA and HNTs imposes a significantly stronger restriction on the relaxation behavior of recycled PET molecular chains than the individual addition of either HNTs or E-MA-GMA. This is attributed to the interfacial reactions between E-MA-GMA and the recycled PET matrix, as well as between E-MA-GMA and HNTs, leading to the formation of branching and hybrid structures. This synergistic restraint markedly reduces the crystallization growth rate of PET. As a result, the recycled PET/E-MA-GMA/HNTs composites maintain relatively lower crystallinity compared with the recycled PET/E-MA-GMA composite after high-temperature injection molding or annealing treatment, leading to superior impact resistance. The impact strength of the recycled PET/E-MA-GMA/HNTs composites is 2.28 and 2.14 times that of the recycled PET/E-MA-GMA composite under high-mold-temperature injection molding and annealing conditions, respectively. The approach presented here facilitates the substitution of virgin plastics with recycled PET in demanding applications. Full article

Increases in global temperatures, due to the climate change, are generating stress in most plant species. We hypothesize that young plants of Opuntia spp. adjust their Crassulacean acid metabolism (CAM) to the increase in nighttime temperature, allowing them to continue growing. The study was carried out in a greenhouse and laboratory of the Colegio de Postgraduados, Montecillo, Mexico. Three-month-old greenhouse-grown plants remained in a control environment with an average day/night temperature of 19.1/12.3 °C or were maintained in a chamber with increased nighttime temperatures averaging 19.1/18.9 °C day/night for 70 days. The experimental design was completely randomized with two treatments (control and high nighttime temperatures). After 70 days of high nighttime temperatures (HNT), at dawn (end of CAM phase I), plants had a 45% decrease in glucose (2.9 to 1.5 mg/100 mg dry tissue; dt) concentration and doubled and tripled fructose (0.43 to 0.95 mg/100 mg dt) and sucrose (0.47 to 0.09 mg/100 mg dt) concentrations. Glucose consumption may be related to the plant’s metabolic energy expenditure to overcome stress. The significant increase in fructose and sucrose is explainable by their function as signaling molecules among others. In contrast, photosynthetic efficiency, i.e., increased compared to the control, but the difference of acidity (end of phase I less phase III), the concentration of starch (1 mg/100 mg dt), free amino acids and soluble protein (1.2 mg/100 mg dt), wet and dry matter, stem height (60 cm) and width of the stem at dawn were not significantly affected. The adjustments in C and N metabolism and the non-significant effect on growth promoted by 70 HNT days may be related to adjustments in enzyme activities without changes in protein concentration. Young Opuntia spp. plants adjust their metabolism in response to increased nighttime temperatures, allowing them to maintain growth similar to that of the control. The results confirm the great potential of using the Opuntia genus in agriculture and genetic improvement in the face of the challenges posed by climatic change. Full article

To address the frequent faults (e.g., bird-related hazards, wind deviation) of transmission lines under extreme environments and the limitations of traditional insulating materials (insufficient dielectric properties, poor interface compatibility, etc.), this study synthesized a disulfide-containing polyurea (DPU) with dynamic covalent bonds and prepared Halloysite nanotubes (HNTs) modified by aminopropyltriethoxysilane (APTES) to form the HNTs/DPU composite. Methods included characterizations like Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and performance tests such as contact angle measurement, breakdown strength, arc resistance, dielectric constant tests, and a tower gap breakdown test. Results showed that APTES modification enhanced interface compatibility, leading to a uniform and dense microstructure. Compared with commercial polyurea (CPU) and commercial insulating sheath (CIS), HNTs/DPU exhibited superior performance: higher glass transition temperature (Tg) and thermal stability, excellent hydrophobicity, improved breakdown strength and dielectric constant, longer arc resistance time by blocking microcrack propagation, and optimal insulation effect at 4 mm coating thickness in the tower gap test with a significantly higher breakdown voltage. In conclusion, HNTs/DPU provides a new technical solution for transmission line insulation protection under extreme conditions, with comparative data demonstrating advancements over existing materials. Full article

Proton binding (i.e., charging) isotherms of halloysite nanotubes (HNT) were determined from cycled acid-base potentiometric titrations in KCl solution at constant ionic strengths (0.01, 0.10, 1.00 mol dm⁻³). The isotherms measured in the pH cycle from 3 to 11 and back exhibit a pronounced hysteresis with respect to the direction of pH change, which is accurately reproducible when the cycle is repeated. The hysteresis is absent if the cycled titration is performed within a narrow pH range between 5 and 9. These results align with the dissolution rates of alumina and silica, which form the two surfaces of the rolled kaolinite sheet in HNT, and clearly point to reversible partial dissolution-deposition processes in the HNT interior during a titration cycle, outside the above pH range (alumina dissolution below pH ≈ 5 and silica dissolution above pH ≈ 8.5). In the studied titration experiments, these processes produce partially dissolved surface-bound, rather than completely dissolved species (reversible surface etching). Under the applied conditions, reversible surface etching is less pronounced in the acidic part of the titration cycle. Charging isotherms recorded in the decreasing pH titrations at varied ionic strength exhibit a common intersection point very close to zero charge (point of zero charge) around pH ≈ 8.1, characteristic for an amphoteric solid surface. These isotherms were reasonably well fitted by applying the surface protonation model in the HNT interior, which invokes the Stern model of the electric double layer (EDL), by summing the surface charges calculated for alumina and silica as separate components (surfaces). The model surface charge isotherms for alumina surface in the HNT interior exhibit a point of zero charge at pH = 9.0, while the silica surface has a negative charge above pH > 8.5, which is in very good agreement with the values reported in the literature: as for these two surfaces, thus for kaolinite nanoparticles. The best-fit protonation site density for both surfaces is equal to 8.0 nm⁻², while the best-fit intrinsic pK_a for alumina and silica surfaces of HNT are equal to 9.0 and 8.5, respectively. The pH-dependence of electrophoretic mobility, measured by means of electrophoretic light scattering, reveals a more acidic behavior of the outermost silica surface than within the inner HNT phase, which is consistent with the literature result reported for kaolinite. The results reported herein confirm that the inner and outer surfaces of the HNT are oppositely charged below pH < 8.0 and negatively charged above that value, and importantly, they reveal new details about the protonation affinities and EDL parameters at active surfaces of HNT, important for the colloidal stability of HNT suspensions and the functionalization of HNT through the electrostatic binding of active molecules. Full article

Polylactic acid (PLA) is a biodegradable polymer with an ever-increasing number of applications, although its inherent brittleness limits its performance somewhat in structural applications. In this study, we analysed the influence of incorporating multi-walled carbon nanotubes (MWCNTs) and halloysite nanotubes (HNTs) at different concentrations (0.5, 0.75 and 1 wt%) on the mechanical properties of injection-moulded PLA nanocomposites. The effects of the nanofillers were characterised by tensile, flexural, and impact tests, hardness measurements, and FESEM examination. The results showed that MWCNTs increased the flexural strength and stiffness by up to 60% compared to neat PLA (84.3 vs. 52.6 MPa), although this was accompanied by a reduction in elongation at break (from 2.30% to 1.57%) due to agglomeration. Conversely, HNTs improved the elongation at break up to 6.39%, enhanced flexural strength by approximately 62% (85.1 MPa), and maintained stiffness around 3.0 GPa, indicating a better balance between strength and ductility. The FESEM micrographs confirmed the presence of clusters in MWCNTs and a more homogeneous dispersion in HNTs, thus explaining the differences in behaviour. Overall, MWCNTs are more suitable for applications requiring high stiffness and strength, whereas HNTs are preferable when greater ductility and impact resistance are required. Full article

As a fundamental component of sodium-ion batteries, separators are considered to isolate two electrodes and simultaneously allow for the transport of ions. Cellulose separators have attracted widespread interest for their remarkable properties. In this study, we prepared composite separators comprising cellulose nanofibers (CNFs) and halloysite nanotubes (HNTs) for sodium-ion batteries. When the content of the HNT was up to 60%, the tensile strength and elongation at break of the composite separator (denoted as C/H-60) were 24.39 MPa and 2.22%, respectively. Importantly, the C/H-60 separator demonstrated a high porosity (69.08%), improved ionic conductivity (1.142 mS/cm), decent thermal stability, and good electrolyte retention (91.3% electrolyte uptake). The assembled sodium-ion battery containing the composite separators had an excellent rate capacity and cycling property. The proposed composite separators are expected to be applied in high-performance sodium-ion batteries. Full article

This study reports the preparation of alginate (Alg) beads incorporating different amounts of halloysite nanotubes (HNTs) and kaolin (K) in the presence of Ca²⁺ ions to compare their drug loading and release behaviors. The resulting composites, HNTs@Alg and K@Alg, were characterized using FTIR, SEM–EDS, XRD, and XPS analyses. Chlortetracycline hydrochloride (CTC) was employed as a model antibiotic to evaluate their drug delivery performance. The concentration of Alg and the incorporation of HNTs or K markedly influenced the adsorption capacity and release profile. The maximum drug loading capacities were 48.12 ± 1.4 mg/g for HNTs, 40.1 ± 1.2 mg/g for K, 59.85 ± 2.3 mg/g for HNTs@Alg-1 (1 g HNTs and 1% Alg), and 68.74 ± 2.1 mg/g for K@Alg-1 (1 g K and 1% Alg). The inclusion of Alg enhanced sustained release, extending beyond 100 h. Among the composite beads, HNTs@Alg-1 showed superior CTC release behavior compared to K@Alg-1. Furthermore, antibacterial assays confirmed that the CTC-loaded beads effectively inhibited E. coli and S. aureus, demonstrating maintained drug activity after encapsulation. Both systems effectively prolonged CTC release and exhibited antibacterial efficacy, highlighting their potential as controlled drug delivery matrices for wound treatment applications. Full article

The development of advanced wound dressings that integrate favorable physico-mechanical properties with the ability to support physiological healing processes remains a critical challenge in biomaterials science. An ideal dressing should modulate the wound microenvironment, prevent infection, maintain hydration, and possess adequate strength and elasticity. This study aimed to fabricate and characterize electrospun chitosan (CS)-based 3D scaffolds dual-reinforced with halloysite nanotubes (HNTs) and cerium oxide nanoparticles (CeONPs) to enhance material properties and biological performance. HNTs were incorporated to improve electrospinnability and provide mechanical reinforcement, while CeONPs were added for their redox-modulating and anti-inflammatory activities. Composite mats were fabricated via non-capillary electrospinning. The individual and synergistic effects of HNTs and CeONPs were systematically evaluated using physico-chemical methods (SEM, EDX, WAXS, TGA, mechanical testing) and biological assays (in vitro cytocompatibility with mesenchymal stem cells, in vivo biocompatibility, and wound healing efficacy in a rat model). Scaffolds containing only HNTs exhibited defect-free nanofibers with an average diameter of 151 nm, whereas the dual-filler (CS-PEO-HNT-CeONP) composites showed less uniform fibers with a rough surface and a larger average diameter of 233 nm. The dual-filler system demonstrated significantly enhanced mechanical properties, with a Young’s modulus nearly double that of pure CS mats (881 MPa vs. 455 MPa), attributed to strong interfacial interactions. In vivo, the CS-PEO-HNT-CeONP scaffolds degraded more slowly, promoted earlier formation of a connective tissue capsule, and elicited a reduced inflammatory response compared to single-filler systems. Although epithelialization was temporarily delayed, the dual-filler composite ultimately facilitated superior tissue regeneration, characterized by a more organized, native-like collagen architecture. The synergistic combination of HNTs and CeONPs within a CS matrix yields a highly promising scaffold for wound management, offering a unique blend of tailored biodegradability, enhanced mechanical strength, and the ability to guide healing towards a regenerative rather than a fibrotic outcome, particularly for burns and traumatic injuries. Full article

The presence of metallic pollutants presents a significant risk to human health, making their removal crucial. Magnetic halloysite nanotube (HNT@Fe₃O₄) nanocomposite was synthesised via co-precipitation, and then magnetic hydrogel (Fe₃O₄@HNT-SA and Fe₃O₄@HNT-CTS) nanocomposites were prepared using chitosan (CTS) and sodium alginate (SA) biopolymers. The structural, morphological, crystalline, surface, and thermal properties of the hydrogels were determined. The favourable adsorption performance of Fe₃O₄@HNT-SA and Fe₃O₄@HNT-CTS hydrogels towards As, Cd, Cr, Mo, Pb, Sb and V was established by optimising the factors affecting the sorption process. The results indicated that Fe₃O₄@HNT-CTS was suitable for the adsorption of As, Cr, Mo, Sb and V, while Fe₃O₄@HNT-SA had high adsorption affinity for Cd and Pb. The data for the adsorption of target analytes onto the hydrogels were mostly explained by both the Langmuir isotherm model and the pseudo-second order model. The maximum adsorption capacities of Fe₃O₄@HNT-SA hydrogel for Cd and Pb were 52.2 mg/g and 57.7 mg/g, respectively. On the other hand, the maximum capacities of the Fe₃O₄@HNT-CTS hydrogel for As, Cr, Mo, Sb, and V were 30.3 mg/g, 28.4 mg/g, 22.2 mg/g, 24.7 mg/g, and 19.9 mg/g, respectively. The Fe₃O₄@HNT-SA and Fe₃O₄@HNT-CTS hydrogels effectively removed the respective target analytes from river water samples. Full article

Background: Poor water solubility is a major limitation for the therapeutic use of many anticancer drugs. In this study, we report the design and development of two halloysite-based hybrid nanomaterials for the encapsulation and delivery of hydrophobic and positively charged drugs. Methods: A novel multicavity platform was obtained by covalently grafting calix[5]arene macrocycles onto the external surface of halloysite nanotubes (HNTs), combining lumen encapsulation with supramolecular host–guest recognition. PB4, a planar and hydrophobic pyridinium salt with significant antiproliferative activity, was selected as a model compound. Both PB4-loaded HNTs (HNTs/PB4) and calixarene-functionalized HNTs (HNTs-Calix/PB4) were incorporated into Laponite^®-based thixotropic hydrogels to obtain injectable and biocompatible systems. Results: The nanomaterials were thoroughly characterized, and their loading efficiency, release behavior, and aqueous dispersibility were evaluated. Antiproliferative tests on MCF-7 cells demonstrated that both hydrogels retained PB4 activity, with distinct release profiles: the pristine HNTs allowed faster drug availability, while calix[5]arene-functionalized systems promoted sustained release. Conclusions: This work introduces the first example of covalently calixarene-functionalized halloysite and presents a versatile drug delivery platform adaptable to different therapeutic contexts and combination strategies. Full article

Lung cancer is the leading cause of cancer mortality worldwide, with a poor prognosis driven by late diagnosis, systemic toxicity of existing therapies, and rapid development of multidrug resistance (MDR) to agents such as paclitaxel and cisplatin. MDR arises through multiple mechanisms, including overexpression of efflux transporters, alterations in apoptotic pathways, and tumour microenvironment-mediated resistance. The application of nanotechnology offers a potential solution to the aforementioned challenges by facilitating the enhancement of drug solubility, stability, bioavailability, and tumour-specific delivery. Additionally, it facilitates the co-loading of agents, thereby enabling the attainment of synergistic effects. Halloysite nanotubes (HNTs) are naturally occurring aluminosilicate nanocarriers with unique dual-surface chemistry, allowing hydrophobic drug encapsulation in the positively charged lumen and functionalisation of the negatively charged outer surface with targeting ligands or MDR modulators. This architecture supports dual-delivery strategies, enabling simultaneous administration of phytocannabinoids and chemotherapeutics or efflux pump inhibitors to enhance intracellular retention and cytotoxicity in resistant tumour cells. HNTs offer additional advantages over conventional nanocarriers, including mechanical and chemical stability and low production cost. Phytocannabinoids such as cannabidiol (CBD) and cannabigerol (CBG) show multitarget anticancer activity in lung cancer models, including apoptosis induction, proliferation inhibition, and oxidative stress modulation. However, poor solubility, instability, and extensive first-pass metabolism have limited their clinical use. Encapsulation in HNTs can overcome these barriers, protect against degradation, and enable controlled, tumour-targeted release. This review examined the therapeutic potential of HNT-based phytocannabinoid delivery systems in the treatment of lung cancer, with an emphasis on improving therapeutic selectivity, which represents a promising direction for more effective and patient-friendly treatments for lung cancer. Full article

Surface functionalization is a key enabler that imparts solid materials with excellent chemoselectivity. With this aim, halloysite and sepiolite clay particles were functionalized with carboxyethylsilanetriol sodium salt (CES) and 3-aminopropyltriethoxysilane (APTES), affording carboxy-terminated and amino-terminated clay, respectively. In the case of halloysite, the grafting occurs at Al-OH groups of the lumen surface (tube inner surface) and Al-OH and Si-OH groups at the edges and external surface defects of the nanotubes. For sepiolite, silanol groups located on the edges of the structural channels were at the origin of a chemical reaction between this fibrous clay and the terminal alkoxysilane. The resulting modified clays were examined for removal of Congo red (CR) and malachite green (MG) as anionic and cationic dyes, respectively. Clay bearing only carboxylic groups display more affinity towards cationic dye (MG), recording 926 mg·g⁻¹ and 387 mg·g⁻¹ for HNT-CES and SEP-CES, respectively, while amino-functionalized clays show very high adsorption for anionic dye (CR), reaching 1232 and 1228 mg·g⁻¹ for HNT-APTES and SEP-APTES, respectively. Simultaneous grafting of the two silyl coupling reagents was also attempted through one-pot and sequential grafting method, with the latter being more appropriate to access amphoteric clay featuring both carboxylic and amino groups. The behavior of the bifunctional adsorbents was investigated with respect to pristine and monofunctional clay. The obtained results provide insights to fulfill the requirement for handling complex water effluent containing both anionic and cationic pollutants, towards more sustainable development. Full article

High nighttime temperature (HNT) due to asymmetric diurnal warming threatens wheat productivity. This study evaluated the effect of HNT on wheat phenology, physiology, and yield through field and controlled environment experiments in Central Queensland, Australia. Two wheat genotypes, Faraday and AVT#6, were assessed under three sowing dates—1 May (Early), 15 June (Mid), and 1 August (Late)—within the recommended sowing window for the region. In a parallel growth chamber study, the plants were exposed to two nighttime temperature regimes, of 15 °C (normal) and 20 °C (high), with consistent daytime conditions from booting to maturity. Late sowing resulted in shortened vegetative growth and grain filling periods and increased exposure to HNT during the reproductive phase. This resulted in elevated floret sterility, lower grain weight, and up to 40% yield loss. AVT#6 exhibited greater sensitivity to HNT despite maturing earlier. Leaf gas exchange analysis revealed increased nighttime respiration (Rn) and reduced assimilation (A), resulting in higher Rn/A ratio for late-sown crops. The results from controlled environment chambers resembled trends of the field experiment, producing lower grain yield and biomass under HNT. Cumulative nighttime hours above 20 °C correlated more strongly with yield losses than daytime heat. These findings highlight the need for HNT-tolerant genotypes and optimized sowing schedules under future climate scenarios. Full article