Addition Of Halloysite Nanotubes Research Articles

Development and characterization of a novel pH-Responsive nanocarrier for enhanced quercetin delivery and cytotoxicity in lung cancer

Quercetin (QC) is a potent polyphenol with numerous health benefits, but its use is limited due to its low bioavailability and high toxicity. Accordingly, a pH-responsive nanocarrier was created using chitosan (CS), halloysite nanotubes (HNTs), and graphene quantum dots (GQDs). It was found that LE and EE values of the CS/GQDs nanocomposites were 32.0% and 69.0%, respectively, increasing to 44.25% and 85.5% upon HNTs addition. The QC release study of pH-responsive CS/HNTs/GQDs nanocomposite in buffer environments showed that with the presence of GQDs in the CS/HNTs composite, the release rate increased from 73% and 54% at pH 5.4 and 7.4 to 97.5% and 67%. Examining the release data with kinetic models showed that the data corresponded to the first-order model, which indicates concentration-dependent drug release. In this study, the cytotoxicity of CS/HNT, CS/HNTs/GQDs, and CS/HNTs/GQDs@QC nanocomposites against L929 and A549 lung cell lines was investigated. The results showed that CS/HNTs/GQDs@QC had the highest cytotoxicity and had a more profound effect on A549 cells. The proportion of apoptotic cells in the CS/HNTs/GQDs@QC group was also higher than in the control group, with early and late apoptosis of 74.4% and 5.15%, respectively.

Modification of polymethylmethacrylate bone cement with halloysite clay nanotubes

BackgroundPolymethylmethacrylate (PMMA) bone cement is used in orthopedics and dentistry to get primary fixation to bone but doesn’t provide a mechanically and biologically stable bone interface. Therefore, there was a great demand to improve the properties of the PMMA bone cement to reduce its clinical usage limitations and enhance its success rate. Recent studies demonstrated that the addition of halloysite nanotubes (HNTs) to a polymeric-based material can improve its mechanical and thermal characteristics.ObjectivesThe purpose of the study is to assess the compressive strength, flexural strength, maximum temperature, and setting time of traditional PMMA bone cements that have been manually blended with 7 wt% HNT fillers.MethodsPMMA powder and monomer liquid were combined to create the control group, the reinforced group was made by mixing the PMMA powder with 7 wt% HNT fillers before liquid mixing. Chemical characterization of the HNT fillers was employed by X-ray fluorescence (XRF). The morphological examination of the cements was done using a scanning electron microscope (SEM). Analytical measurements were made for the compressive strength, flexural strength, maximum temperature, and setting time. Utilizing independent sample t-tests, the data was statistically assessed to compare mean values (p < 0.05).ResultsThe findings demonstrated that the novel reinforced PMMA-based bone cement with 7 wt% HNT fillers showed higher mean compressive strength values (93 MPa) and higher flexural strength (72 MPa). and lower maximum temperature values (34.8 °C) than the conventional PMMA bone cement control group, which was (76 MPa), (51 MPa), and (40 °C), respectively (P < 0.05). While there was no significant difference in the setting time between the control and the modified groups.ConclusionThe novel PMMA-based bone cement with the addition of 7 wt% HNTs can effectively be used in orthopedic and dental applications, as they have the potential to enhance the compressive and flexural strength and reduce the maximum temperatures.

Nanofiller‐and basalt fiber‐reinforced recycled polyamide 6 hybrid composites

AbstractThe influence of nanofillers (cellulose nanofibers (CNF) and halloysite nanotubes (HNTs)), and basalt fibers (BF) on the morphology, mechanical and thermal of recycled polyamide 6 (PA6) composites were investigated through scanning electron microscopy (SEM), mechanical testing, rotational rheometry, dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). CNF, HNTs and BF were relatively well‐dispersed in the PA6 matrix and the incorporation of these nanofillers and BF increased the strength of the matrix, which indicates a good dispersion of the nanofillers and BF. CNF and HNTs‐filled PA6 nanocomposites increased the tnsile strength by 14% and 6% compared to the neat PA6, respectively. The composites elongation at break decreased with nanofiller, BF and combined nanofillers and BF. The shear storage modulus values of PA6/20B5C, PA6/20B5H, and PA6/25B are significantly elevated compared to neat PA6, with increases of 3.7, 2.8, and 2.5 times, respectively, at an angular frequency of 100 rad/s. PA6/20B5H composites with 20 wt.% BF and 5 wt.% HNTs exhibited the highest storage modulus (9.5 GPa) from the DMA study. Thermal stability and ash content at 800°C increased with the incorporation of HNTs and BF. The DSC findings showed that the glass transition (Tg) and melting temperature (Tm) of the composites did not exhibit any notable changes when nanofillers and BF were added to the resin. The nucleation ability of PA6 was enhanced attributable to BF and hybridization of BF and nanofillers since the crystallization temperatures of PA6 in BF filled and hybrid composites were around 5°C greater than neat PA6. The results suggest hybrid composites with potential environmental characteristics and higher mechanical properties can be utilized in semi‐structural applications in automotive and construction as a sustainable and lightweight alternative to steel and other materials.Highlights The addition of HNTs, CNF, BF and hybridization of nanofillers with BF reduced the brittleness of PA6. Nanoreinforced and hybrid PA6 composites achieved higher storage modulus than neat PA6. Thermal stability and ash content increased with the incorporation of HNTs and BF. The hybrid composites have a higher complex viscosity compared to PA6. The sustainable hybrid composites can be utilized in automotive and construction industries.

Influence of silica rich HNT/MoS2 hybrid reinforcements on mechanical, wear and corrosion characteristics of magnesium AZ31 alloy

This article examines the effects of combining silica-rich Halloysite Nano Tube (HNT) and Molybdenum di Sulphide (MoS2) as hybrid reinforcements, dispersed at volumes of 2, 4, and 6%, on the surface of AZ31 alloy through the application of the friction stir process (FSP). The prepared composites were analysed to evaluate their microstructure, mechanical properties, wear resistance, and corrosion characteristics. Microstructural observations indicate the occurrence of rapid recrystallization, resulting in reduced grain size and uniform dispersion. The surface composite demonstrates an increasing trend in hardness with the addition of HNT, while hardness decreases with the inclusion of MoS2. The micro tensile test results exhibits that the composite exhibits an increasing trend in strength, while the micrograph of the fractured surface of the micro tensile specimens reveals reduced ductility. The composite displays enhanced wear behaviour with the increasing volume percentages of HNT and MoS2 particles. Solid lubricant nature of the secondary reinforcement and enhanced hardness due to HNT addition and FSP leads to higher wear resistance of the developed hybrid composite. Additionally, the corrosion rate decreases with the addition of HNT, whereas higher concentrations of MoS2 lead to increased corrosion.

Investigation of the influence of Halloysite Nanotubes (HNTs) on the low-velocity impact behavior of carbon fiber-reinforced epoxy composites

This study explores the impact of incorporating Halloysite Nanotubes (HNTs) nanoparticles on the low-velocity impact (LVI) behavior of carbon fiber (CF) laminate epoxy nanocomposites. The objective of this investigation was to observe the effects of different nanotube loadings (0.5[Formula: see text]wt.% and 0.7[Formula: see text]wt.%) on CF composites and assess their impact resistance. To achieve this, the CF was subjected to Electrophoretic Deposition (EPD) process to introduce the HNTs. Vacuum-assisted Resin Transfer Molding (VaRTM) was employed to fabricate the CF-reinforced epoxy-based laminated nanocomposites with incorporated HNTs. LVI tests were conducted following the ASTM-D-7136 standard, utilizing impact energies of 10[Formula: see text]J and 15[Formula: see text]J. Subsequently, the damaged areas within the composites were examined using optical microscopy (OM) and scanning electron microscope (SEM). The findings of this investigation revealed a significant enhancement in impact damage resistance with the addition of HNTs. The highest damage resistance and minimal energy absorption were observed at a loading of 0.7[Formula: see text]wt.% HNTs. The results reveal that incorporating 0.7[Formula: see text]wt.% HNTs substantially reduces delamination damage, influenced by absorbed impact energy. As well it composite underscores enhanced interlaminar bonding through 0.5[Formula: see text]wt.% and 0.7[Formula: see text]wt.% HNTs modification. Hence, we confidently assert that the addition of HNTs nanoparticles to CF/epoxy composites has considerably influenced the impact response of the nanocomposites.

Effect of freeze–thaw manipulation on phytostabilization of industrially contaminated soil with halloysite nanotubes

The latest trends in improving the performance properties of soils contaminated with potentially toxic elements (PTEs) relate to the possibility of using raw additives, including halloysite nanotubes (HNTs) due to eco-friendliness, and inexpensiveness. Lolium perenne L. was cultivated for 52 days in a greenhouse and then moved to a freezing–thawing chamber for 64 days. HNT addition into PTE-contaminated soil cultivated with grass under freezing–thawing conditions (FTC) was tested to demonstrate PTE immobilization during phytostabilization. The relative yields increased by 47% in HNT-enriched soil in a greenhouse, while under FTC decreased by 17% compared to the adequate greenhouse series. The higher PTE accumulation in roots in HNT presence was evident both in greenhouse and chamber conditions. (Cr/Cd and Cu)-relative contents were reduced in soil HNT-enriched-not-FTC-exposed, while (Cr and Cu) in HNT-enriched-FTC-exposed. PTE-immobilization was discernible by (Cd/Cr/Pb and Zn)-redistribution into the reducible fraction and (Cu/Ni and Zn) into the residual fraction in soil HNT-enriched-not-FTC-exposed. FTC and HNT facilitated transformation to the residual fraction mainly for Pb. Based on PTE-distribution patterns and redistribution indexes, HNT’s role in increasing PTE stability in soils not-FTC-exposed is more pronounced than in FTC-exposed compared to the adequate series. Sphingomonas, Acidobacterium, and Mycobacterium appeared in all soils. HNTs mitigated FTC’s negative effect on microbial diversity and increased Planctomycetia abundance.

Polyurethane-Based Nanocomposites for Regenerative Therapies of Cancer Skin Surgery with Low Inflammatory Potential to Healthy Fibroblasts and Keratinocytes In Vitro.

Nanocomposites based on thermoplastic polyurethanes (TPUs) filled with halloysite nanotubes (HNTs) were studied for their physicochemical and biological properties. Nanocomposites containing halloysite nanotube filler contents of 1 and 2% (E+1 and E+2), respectively, were obtained by extrusion. The newly formed E+1 and E+2 nanomaterials exhibited better flexibility and similar thermal properties compared to neat polyurethane. The use of atomic force microscopy (AFM) and differential scanning calorimetry (DSC) thermogram analysis showed that the distribution of halloysite nanotubes in the polymer matrix is more evenly dispersed in the E+1 nanomaterial, where the grains in the E+2 nanomaterial have a greater tendency to form agglomerates. Mechanical tests have shown that nanocomposites with the addition of HNT are characterized by a higher stress at break and elongation at break compared to neat TPU. The results of cytotoxicity tests suggest that the nanocomposite materials express lower toxicity to normal HaCaT and NHDF than to cancer Me45 cells. Further studies showed that the tested materials induced the expression of proinflammatory interleukins IL6 and IL8 in normal cells, but their overexpression in the cancer cell line resulted in cytostatic effects and proliferation reduction. Such a conclusion suggests the possible application of tested materials for regenerative therapies in cancer surgeries.

Influence of water absorption on the interlaminar behavior of carbon fiber-reinforced composites containing halloysite nanotubes

Polymer matrix composites deteriorate during prolonged exposure to water, especially at the fiber–matrix interface. Herein, water absorption and interfacial mechanical property degradation were evaluated after the addition of halloysite nanotubes (HNTs), which are inexpensive tube-shaped nanofillers. The water absorption ratio of the composite containing HNTs was lower than that of the reference. The mechanical properties, including flexural strength and interlaminar shear strength, were also less degraded in the composite containing HNTs. This improvement was attributed to the HNT nanofiller reinforcing the matrix and bridging propagating cracks. Concurrently, the HNTs acted as a water absorbent and water barrier, thereby preventing damage to the fiber–matrix interface by water. Halloysite nanotubes are suitable as a filler for applications exposed to high humidity or aqueous environments.

Enhancing self‐healing efficiency of natural rubber composites using halloysite nanotubes

AbstractThis study aimed to explore the reinforcement effect of halloysite nanotubes (HNTs) in self‐healing natural rubber based on metal thiolate ion networks. The amount of HNTs was varied at five levels (2, 4, 6, 8, and 10 phr) in order to assess the optimum amount of filler for self‐healing efficiency and mechanical recovery performance. Fourier‐transform infrared (FTIR) provides evidence for the reversible ionic bonding, facilitated by Zn2+ and S− bonding from the metal thiolate vulcanization with rubber molecular chains. Scanning electron microscopy (SEM) revealed that the NR/HNTs composites with lower filler loading exhibited better recovery, as there were no observable gaps between the cut surfaces of the samples. The results also revealed that addition of HNTs resulted in a significant improvement in the mechanical performance, particularly the tensile strength, which increased by approximately 20%–75%. Furthermore, the extent of healing after the broken pieces were brought in contact with each other varied from 87% to 98%, depending on HNT concentration.Highlights Fabrication of self‐healing elastomers based on natural rubber. Self‐healing NR presented enhanced mechanical performance with addition of HNTs. HNTs lumen endows the composites with excellent self‐healing efficiency. Developed NR/HNTs composite exhibited room temperature self‐healing properties. Reversible ionic bonding expedited by Zn2+ contributes in excellent self‐healing.

An experimental investigation of the tensile, fracture and microstructural characteristics of ABS/SBS reinforced with HNTs

AbstractThermoplastic composites are broadly used in many industries. Excellent mechanical characteristics are frequently required to achieve the appropriate properties for the applications. Therefore, the objectives of this study were (1) presenting an in‐depth analysis of the effects of styrene butadiene styrene (SBS) and halloysite nanotubes (HNTs) on the tensile and fracture properties of the thermoplastic composites based on acrylonitrile butadiene styrene (ABS), and (2) examining the relationship between the microstructure of the thermoplastic composites and their mechanical behavior. For these purposes, HNTs were utilized with four levels (0, 1, 3, and 5 wt%) and SBS was used with two levels (15 and 30 wt%). The tensile strength and modulus were reduced by adding SBS to 30 wt%; however, the elongation at break was increased by 30%. Furthermore, tensile strength and modulus, and elongation at break were improved by increasing HNTs up to 3 wt%. The results indicated the elastic work (we) and plastic work (βwp) rose by 29% and 10%, respectively, when 30 wt% of SBS was added to ABS. Furthermore, we and βwp rose by the addition of HNTs up to 3 wt%. To examine fracture mechanisms, field emission scanning electron microscope (FESEM) images of the fracture surface of the essential work of fracture (EWF) specimens were taken. Several voids are present in the compounds containing SBS, activating the plastic deformation mechanism. Based on the optimization process, the best strength, stiffness, and toughness balance was attained for the compound consisting of 15 wt% SBS and 1 wt% HNTs.Highlights The effects of HNTs and SBS on the fracture properties of polymer composites. The addition of SBS increased we, βwp, and the elongation at break. HNTs had a positive effect on the tensile strength and modulus, we, and βwp. The important mechanisms include plastic deformation and cavitation.

Immobilization capacity assessment of a binder from arsenic-containing biohydrometallurgy waste: Effects of halloysite nanotubes and biochar addition

The aim of this study was to improve the immobilization capacity of a binder prepared from As-containing biohydrometallurgy waste (BAW) on arsenic (As) by modifying it with halloysite nanotubes (HNTs) and biochar (BC). The study investigated the influence of HNTs and BC on the chemical fractions and leaching characteristics of As, as well as the influence on the compressive strength of BAW. The results indicated that the addition of HNTs and BC effectively decreased As leaching. The presence of 1.0 wt% HNTs decreased the As leaching concentration from 1.08 mg/L to 0.15 mg/L, with the corresponding immobilization rate reaching about 90.9 %. A high amount of BC seemed to show better performance in improving the As immobilization capacity of BAW. However, a strongly reduced early compressive strength of BAW was observed, making it unsuitable to be used as an additive in this situation. The effects of HNTs on the increase of As immobilization capacity of BAW were attributed to two aspects. Firstly, As species were adsorbed onto the surface of HNTs via H-bonds, which was verified via density functional theory calculation. Secondly, the addition of HNTs decreased the pore volume of BAW, leading to a more compact structure, and hence increasing the physical encapsulation capacity for As. Environmental implicationThe rational disposal of arsenic-containing biohydrometallurgy waste has always been a top priority for the green and low-carbon development of the metallurgical industry. In this article, we have taken the perspective of large-scale resource utilization of solid waste and pollution control, and developed arsenic-containing biohydrometallurgy waste into a cementitious material, and enhancing arsenic immobilization capacity with the addition of HNTs and BC. This study provides an effective method for the rational disposal of arsenic-containing biohydrometallurgy waste.

Thermal, Dynamic Mechanical, Mechanical and Flammability Properties of Halloysite Nanotubes Filled Polyamide 11 Nanocomposites

The effects of various filler contents on the thermal, dynamic mechanical, mechanical, as well as flammability properties of halloysite nanotubes (HNTs) filler and polyamide 11 (PA 11) matrixes are investigated in this research. The nanocomposites were made out of 100 phr of PA 11 and three distinct HNTs loadings of 2, 4, and 6 phr each. PA 11 nanocomposites without HNTs filler was used as the reference sample. To melt-compound the nanocomposites, a twin-screw extruder was used, and the specimen for testing was then injected using an injection mold. SEM, TGA, DSC, FTIR, DMA, tensile, flexural, impact, and UL-94 flammability tests were conducted on the nanocomposites. Incorporation of 4 phr HNTs into the nanocomposites resulted in the highest tensile and flexural strength. Maximum improvement in the DMA, Young’s and flexural modulus was achieved at 6 phr HNTs content. The elongation at break and TGA resulted the highest increase at 2 phr HNTs content. However, the impact strength decreased with increasing HNTs content. Scanning electron microscopy revealed the ductility of the nanocomposites with increased HNTs content up to 4 phr. The DSC showed a steady increase in melting temperature (Tm) as HNTs content increased up to 4 phr, while the crystallization temperature (Tc) remained unchanged. TGA of PA 11/HNTs nanocomposites showed high thermal stability at 2 phr HNTs content. However, on further addition of HNTs up to 6 phr, thermal stability of the nanocomposites decreased due to the excess amount of HNTs. All the nanocomposites passed the horizontal and vertical UL-94 test with HB and V-2 grade. PA 11/4HNTs nanocomposite has the highest tensile strength, flexural strength compared to other PA 11/HNTs nanocomposites. PA 11/4HNTs nanocomposite can be suggested as an optimum formulation with balanced mechanical properties in terms of toughness.

Investigating functional properties of halloysite nanotubes and propolis used in reinforced composite film based on soy protein/basil seed gum for food packaging application

This study aimed to investigate the effect of halloysite nanotubes (HNTs) on the physicochemical characteristics of the soy protein isolated/basil seed gum (SPI/BSG) film activated with propolis (PP). The obtained results of scanning electron microscope (SEM), thermal gravimetric analysis (TGA), and tensile investigations illustrated that the addition of HNTs as nanofiller led to positive changes in the morphology, thermal stability, and mechanical characteristics of SPI/BSG films. The barrier properties of films considerably decreased with incorporation of HNTs. Furthermore, the encapsulation of PP as bioactive agent into the produced films significantly increased (P < 0.05) the antioxidant potential of the samples in DPPH radical-scavenging activity assays. The antibacterial effects of film also significantly increased (P < 0.05) after the encapsulation of PP. In conclusion, the produced films illustrated acceptable efficiency for usage in food packaging system.

The thermal behavior and flame retardant performance of phase change material microcapsules with halloysite nanotube

Phase change material (PCM) has the potential to be added in coatings for energy-saving while the drawback of low thermal conductivity, poor thermal stability and flammability restrict its application. In this study, a novel halloysite nanotube (HNT) doped PCM (H-PCM) microcapsule was successfully prepared and applied in epoxy resin (EP) coatings (H-PCM-EP) to achieve temperature control. Many characteristics of the prepared PCM microcapsule were examined such as surface morphology, phase transformation performance and combustion data. The results indicated that the H-PCM microcapsule with a clear core-shell structure were successfully prepared. In comparison with the pristine PCM microcapsule, the H-PCM microcapsule had better thermostability and thermal conductivity. While the melting process of capric acid in H-PCM microcapsule advanced from 31.62 °C to 31.04 °C when compared with PCM microcapsule, which was considered as the bridge-like function of HNT. Moreover, the flammability and temperature control ability of H-PCM-EP were also investigated. The data of the peak heat release rate, total heat release, and total smoke release showed that the addition of HNT in PCM microcapsule can significantly reduce the influence of PCM in EP composites on fire hazards. Notably, the results of the small room model test and infrared thermal imager suggested that the application of H-PCM-EP can regulate inner room temperature and maintain a comfortable temperature range with less fluctuation. These properties will promote the application of the H-PCM microcapsule in temperature control coatings.

Acrylic Rubber-Reinforced Halloysite Nanotubes/Carbon Black Hybrid Fillers for Oil Seal Applications: Thermal Stability and Dynamic Mechanical Properties

In this study, we show that adding halloysite nanotubes (HNT) to carbon black (CB)-packed acrylic rubber (ACM) composites improves their thermal properties. The thermo-oxidative stability, thermal stability, and dynamic mechanical properties of ACM composites (filled simply with 70 phr CB) and ACM hybrid composites comprising a fixed amount of CB (60 phr) and a variable amount of halloysite nanotubes (HNT) (2, 4, 6, 8, and 10 phr) were investigated. As evidenced by the oxidation induction time analysis, hybrid structures support a higher degree of antioxidation in composites reinforced with twin fillers than composites reinforced just with CB. ACM composites with dual fillers had greater breakdown temperatures (temperatures at 10% weight loss (T10) and 50% weight loss (T50)) and char residue concentration at 600°C than ACM conventional composites, according to thermogravimetric tests. The activation energy of the thermal disintegration of ACM composites, as determined by the Kissinger and Flynn–Wall–Ozawa techniques, shows that the addition of HNT improves the thermal stability of ACM composites. The storage modulus of ACM composites was increased by 79 percent at 30°C when 10 phr of black filler was replaced with 6 phr of tubular HNT, according to additional viscoelastic experiments.

Keratin/alginate hybrid hydrogels filled with halloysite clay nanotubes for protective treatment of human hair

Keratin/alginate hydrogels filled with halloysite nanotubes (HNTs) have been tested for the protective coating of human hair. Preliminary studies have been conducted on the aqueous colloidal systems and the corresponding hydrogels obtained by using Ca2+ ions as crosslinkers. Firstly, we have investigated the colloidal properties of keratin/alginate/HNTs dispersions to explore the specific interactions occurring between the biomacromolecules and the nanotubes. Then, the rheological properties of the hydrogels have been studied highlighting that the keratin/alginate interactions and the subsequent addition of HNTs facilitate the biopolymer crosslinking. Finally, human hair samples have been treated with the hydrogel systems by the dipping procedure. The protection efficiency of the hydrogels has been evaluated by studying the tensile properties of hair fibers exposed to UV irradiation.In conclusion, keratin/alginate hydrogel filled with halloysite represents a promising formulation for hair protective treatments due to the peculiar structural and rheological characteristics.

Probing the effect of post-curing and halloysite nanotube reinforcement on thermo-mechanical properties of lightweight epoxy syntactic foam composites

This paper deals with an investigation of the post-curing effect of halloysite nanotubes (HNTs) reinforced syntactic foam (HRSF) containing cenosphere as hollow inclusion at 0, 20, and 40 vol% in an epoxy matrix. Compression, flexural, and thermal properties of HRSF (1 vol% HNTs) and cenosphere/epoxy syntactic foam (CESF) composites without HNTs are studied under the influence of post-curing. Further, the post-cured HRSF containing 40 vol% cenosphere (NSF40_H) exhibited a compressive modulus of 33.2% higher than room temperature cured neat epoxy due to improved crosslinking. Addition of HNTs in NSF40_H augments the flexural modulus up to 26.9% compared to post-cured neat epoxy. Additionally, the glass transition temperature ( Tg) of CESF composites with 40 vol% cenosphere was increased by 24.3 °C compared to the room temperature cured sample. This positive shift in Tg can be attributed to the beneficial impact of post-curing, as indicated by differential scanning calorimetry study. Thermogravimetric results demonstrated better thermal stability of HRSF relative to CESF and neat epoxy composites. Transmission electron microscopy illustrated the structure-property correlations of nanotube reinforcement. The improved properties of syntactic foams could be viewed as a potential material for lightweight constructions, especially in the marine and automobile industries.

Photocatalytic H2 evolution properties of K0.5Na0.5NbO3 (KNN) with halloysite nanotubes

By the solid phase reaction method, pure KNN and KNN with different proportions halloysite nanotubes (HNTs) were prepared to study the photocatalytic hydrogen evolution performance under the UV light irradiation. The band gaps of KNN with HNTs are narrower than that of pure KNN. The absorbance of KNN in the ultraviolet region is significantly enhanced by the incorporation of HNTs, where the absorbance in the 200-300 nm region increased about 2 times. Compared with KNN, the conduction band edge of KNN-5wt%HNTs reduced from −1.13 eV to −1.18 eV, showing stronger reducing ability. The H2 production rate of KNN with HNTs is much higher than that of the raw KNN without HNTs. The best H2 production rate of KNN-5wt%HNTs is 31.28 μmol•g−1•h−1, approximate 4.48 times as high as the rate of pure KNN (6.98 μmol•g−1•h−1), suggesting appropriate addition of HNTs can efficiently improve the H2 production efficiency.

Silicon Nitride 3D Printed Implants with Improved Material Properties for Bone Defect Repair

IntroductionPerioperative or latent infections are the typical causes of revision surgeries, requiring the removal and replacement of infected implants. Therefore, biomaterials which promote osseointegration while minimizing the risk of infection are necessary for improved spinal fusion outcomes. Many biomaterials such as PEEK or Titanium are used as an implant. However, most have poor osteoconductive and bacteriostatic properties. Conversely, SN has demonstrated both enhanced osteogenic, hardness, and antimicrobial properties. SN has extremely high strength even up to &gt;1200°C, excellent wear and chipping resistance, high hardness, high fracture toughness. Halloysite nanotubes (HNTs) and metal nanoparticles have been shown to enhance polylactic acid (PLA) and possess antibacterial properties. This research aims to fabricate 3D implants by combining antimicrobial and base polymer powders.MethodsWe used a patented electrodeposition process to coat magnesium (Mg) on the HNT outer surfaces to add additional antimicrobial properties and favorable mechanical properties due to the addition of HNTs. The experiment was set up with SN and metalized halloysite in three concentrations (1%, 5%, and 10%) to achieve the best concentration for the experiment. SEM, EDS, and FTIR were used to confirm Mg presence on the HNT outer surface. Flexural strength test, Hardness test, compression test, contact angle, and porosity test were all used for mechanical testing of the 3D printed composite implant. Gentamicin sulfate, a naturally producing antibiotic by gram‐negative bacteria that can inhibit the growth of both gram‐negative and gram‐positive bacteria, was loaded into the HNT in the fabricated 3D printed implant. Its antimicrobial activity was tested against gram‐positive and gram‐negative bacteria. Samples were conditioned, and then the evaluation of invitro preosteoblast response was evaluated by performing a cytotoxicity test and proliferation assay. Stimulated body fluid was used for in‐vitro assessment to measure the biodegradability of the 3D printed composite.ResultsAntimicrobial testing showed a pronounced bacterial growth inhibition. The effect of SN and metalized HNT on preosteoblasts showed no toxicity and enhanced cell proliferation. In addition, 5% and 10% of SN/MgHNT‐PLA showed greater flexural strength and hardness while also showing a low contact angle after surface coating with protein. SN/MgHNT‐PLA implants also degraded slowly over time.DiscussionThe favorite antimicrobial activity results were obtained by loading the HNT before coating with Mg and then blending with SN. Due to the beneficial physicochemical and biological properties, SN particles have shown great potential as multifunctional building blocks for composites and orthopedic coatings in hard tissue repair/regeneration applications. The introduction of SN on implants enhances cellular surface structure, surface roughness, hydrophilicity, and protein adsorption capability of SN/MgHNT‐PLA 3D printed implants.Significance/clinical relevanceFabricated SN/HNT composite implants showed outstanding mechanical, excellent bacteriostatic property, and osteogenic activity, and offers promise in orthopedic applications.

Halloysite nanotube-based self-healing fluorescence hydrogels in fabricating 3D cube containing UV-sensitive QR code information

With the evolution of information technology, the development of smart materials for the information storage and encryption is in urgent need. Herein, halloysite nanotubes (HNTs)-based self-healing hydrogels were facilely prepared by using aryl arylboronic acid-bearing tetraphenylethylene (TPE) as crosslinker agent, in which the HNTs were covalently bonded into the polymeric matrix. With the addition of HNTs, the obtained hydrogel (H2) shows improved compression resistance performance and self-healing property, which can be customed in certain shapes. The TPE-crosslinked hydrogels (H1 and H2) are able to emit bright blue fluorescence centering at 457 nm when exposed to 365 nm light. By holding together with 1,4-phenylenebisboronic acid-crosslinked hydrogels (H3) with non-fluorescence property, the obtained cube is able to store UV-sensitive QR code information which is potentially to be recognized by QR code scanner or other smart tools.