Hexagonal Boron Nitride Nanoparticles Research Articles

Ag-Doped and Antibiotic-Loaded Hexagonal Boron Nitride Nanoparticles as Promising Carriers to Fight Different Pathogens.

Utilization of antibacterial components-conjugated nanoparticles (NPs) is emerging as an attractive strategy for combating various pathogens. Herein, we demonstrate that Ag/BN NPs and antibiotic-loaded BN and Ag/BN nanoconjugates are promising carriers to fight bacterial and fungal infections. Extensive biological tests included two types of Gram-positive methicillin-resistant Staphylococcus aureus strains (B8469 and MW2), two types of Gram-negative Pseudomonas aeruginosa strains (ATCC27853 and B1307/17), and 47 types of Escherichia coli strains (including 41 multidrug-resistant ones), as well as five types of fungal cultures: Candida albicans (candidiasis-thrush) ATCC90028 and ATCC24433, Candida parapsilosis ATCC90018, Candida auris CBS109113, and Neurospora crassa wt. We have demonstrated that, even within a single genus Escherichia, there are many hospital E. coli strains with multi-drug resistance to different antibiotics. Gentamicin-loaded BN NPs have high bactericidal activity against S. aureus, P. aeruginosa, and 38 types of the E. coli strains. For the rest of the tested E. coli strains, the Ag nanoparticle-containing nanohybrids have shown superior bactericidal efficiency. The Ag/BN nanohybrids and amphotericin B-loaded BN and Ag/BN NPs also reveal high fungicidal activity against C. albicans, C. auris, C. parapsilosis, and N. crassa cells. In addition, based on the density functional theory calculations, the nature of antibiotic-nanoparticle interaction, the sorption capacity of the BN and Ag/BN nanohybrids for gentamicin and amphotericin B, and the most energetically favorable positions of the drug molecules relative to the carrier surface, which lead to lowest binding energies, have been determined. The obtained results clearly show high therapeutic potential of the antibiotic-loaded Ag/BN nanocarriers providing a broad bactericidal and fungicidal protection against all of the studied pathogens.

Tribological properties of hexagonal boron nitride nanoparticles or graphene nanoplatelets blended with an ionic liquid as additives of an ester base oil

AbstractAntifriction synergies between an ionic liquid (IL) and nanopowders as additives of an ester base oil were analysed at rolling conditions. For this aim, two nanodispersions based on hybrid combinations of hexagonal boron nitride nanoparticles (h‐BN) or graphene nanoplatelets (GnP) with tri(butyl) ethylphosphonium diethylphosphate ionic liquid as additives in triisotridecyltrimellitate (TTM) base oil and the mixture of TTM and IL were analysed using two tribometer techniques. Film thickness characterisation and tribological tests were performed at rolling conditions [5% slide‐roll‐ratio (SRR)], under 50N and at operating temperatures of 30, 50 and 80°C. Stribeck curves showed that friction coefficients for the prepared lubricants are lower than those found for the TTM, being the best friction behaviour for the hybrid GnP nanolubricant. Furthermore, friction torque loss tests were performed in rolling ball bearings, observing that for the two hybrid nanolubricants lower friction torque values were obtained.

Synthesis and characterization of silver nanoparticles decorated polydopamine coated hexagonal boron nitride and its effect on wound healing

BackgroundWound healing is an essential physiological process involving many cell types and their products acting in a marvellous harmony to repair damaged tissues. During the healing process, cellular proliferation and extracellular matrix remodelling stages could be interrupted by undesired factors including microorganisms and altered metabolic activities. In such a case, the process requires some external stimulants to accelerate or remediate the healing stages. MethodsIn this study, we report a multifunctional wound healing stimulating agent. In this context, hexagonal boron nitride (hBN) nanoparticles, silver nanoparticles (AgNPs) and polydopamine(pdopa) were used through mussel-inspired chemistry of dopamine to obtain pdopa coated hBN (hBN@pdopa) and AgNPs decorated hBN@pdopa (hBN@pdopa-AgNPs). These two nanostructures were investigated to observe stages of healing. ResultsAgNPs were chosen for inflammation reduction and hBN for induced cell proliferation and migration. In in vitro experiments, firstly, high cellular uptake capacity and biocompatibility of hBN@pdopa and hBN@pdopa-AgNPs were evaluated. They were also tested for their reaction against increased concentration of reactive oxygen species (ROS) in injured cells. Finally, their effect on cellular migration, intracellular tube formation and F-actin organization were monitored by light and confocal microscopy, respectively. ConclusionThe results clearly indicate that the hBN@pdopa-AgNPs significantly decrease ROS production, promote wound closure, and reorganize tube formation in cells.

High-temperature oxidation behavior of SiBN fibers in air

SiBN fibers are one of the most admirable microwave-transparent reinforced materials for high Mach number aircrafts. Currently, the detailed high-temperature oxidation behavior of SiBN fibers has not been studied yet. In this work, we studied the high-temperature oxidation behavior of SiBN fibers with different boron contents at the temperature range of 1000–1400 °C in air. SiBN fibers started to be oxidized at 1100 °C, with Si3N4 and BN phase oxidized to SiO2 and B2O3, respectively. Due to the gasification and the escape of molten B2O3 at high temperatures, amorphous SiO2 could be remained at the fiber surface. As the fiber further oxidized, the molten B2O3 at the inside may infiltrate into the fiber interior to react with Si3N4, causing the precipitation of hexagonal boron nitride (h-BN) nanoparticles and the formation of SiO2/BN layer. Finally, complex oxidation layers with two distinct concentric sublayers accompanied with two transition sublayers could be formed after the oxidizing treatment.

MoS2/h-BN/Graphene Heterostructure and Plasmonic Effect for Self-Powering Photodetector: A Review.

A photodetector converts optical signals to detectable electrical signals. Lately, self-powered photodetectors have been widely studied because of their advantages in device miniaturization and low power consumption, which make them preferable in various applications, especially those related to green technology and flexible electronics. Since self-powered photodetectors do not have an external power supply at zero bias, it is important to ensure that the built-in potential in the device produces a sufficiently thick depletion region that efficiently sweeps the carriers across the junction, resulting in detectable electrical signals even at very low-optical power signals. Therefore, two-dimensional (2D) materials are explored as an alternative to silicon-based active regions in the photodetector. In addition, plasmonic effects coupled with self-powered photodetectors will further enhance light absorption and scattering, which contribute to the improvement of the device’s photocurrent generation. Hence, this review focuses on the employment of 2D materials such as graphene and molybdenum disulfide (MoS2) with the insertion of hexagonal boron nitride (h-BN) and plasmonic nanoparticles. All these approaches have shown performance improvement of photodetectors for self-powering applications. A comprehensive analysis encompassing 2D material characterization, theoretical and numerical modelling, device physics, fabrication and characterization of photodetectors with graphene/MoS2 and graphene/h-BN/MoS2 heterostructures with plasmonic effect is presented with potential leads to new research opportunities.

Hexagonal boron nitride nanoparticles trigger oxidative stress by modulating thiol/disulfide homeostasis.

Hexagonal boron nitride nanoparticles (hBN NPs) are encouraging nanomaterials with unique chemical properties in medicine and biomedical fields. Until now, the optimal hBN NP's dosage and biochemical mechanism that can be used for in vivo systems has not been fully revealed. The main aim of this article is to reveal characteristics, serum and tissue interactions and any acute cytotoxic effect of different dose of hBN NPs for the first time. hBN NPs at concentrations varying between 50-3200 µg/kg was administered by intravenous injection to Wistar albino rats (n = 80) divided into seven dosage and control groups. Blood and tissue samples were taken after 24 hours. Our findings suggested that higher doses hBN NPs caused oxidative stress on the serum of rats dose-dependently. However, hBN NPs did not affect thiol/disulfide homeostasis on kidney, liver, spleen, pancreas and heart tissue of rats. Furthermore, hBN NPs increased serum disulfide formation by disrupting the thiol/disulfide balance in rats. Also, LOOH and MPO levels increased at high doses, while CAT levels decreased statistically. The results revealed that hBN NPs induce oxidative stress in a dose-dependent manner by modulating thiol/disulfide homeostasis in rats at higher concentrations.

Bottom-Up Synthesis of Hexagonal Boron Nitride Nanoparticles with Intensity-Stabilized Quantum Emitters.

Fluorescent nanoparticles are widely utilized in a large range of nanoscale imaging and sensing applications. While ultra-small nanoparticles (size ≤10nm) are highly desirable, at this size range, their photostability can be compromised due to effects such as intensity fluctuation and spectral diffusion caused by interaction with surface states. In this article, a facile, bottom-up technique for the fabrication of sub-10-nm hexagonal boron nitride (hBN) nanoparticles hosting photostable bright emitters via a catalyst-free hydrothermal reaction between boric acid and melamine is demonstrated. A simple stabilization protocol that significantly reduces intensity fluctuation by ≈85% and narrows the emission linewidth by ≈14% by employing a common sol-gel silica coating process is also implemented. This study advances a promising strategy for the scalable, bottom-up synthesis of high-quality quantum emitters in hBN nanoparticles.

Tribological properties of graphene nanoplatelets or boron nitride nanoparticles as additives of a polyalphaolefin base oil

In this work, antifriction and antiwear capabilities of hexagonal boron nitride nanoparticles (h-BN) or graphene nanoplatelets (GnP) as additives of a polyalphaolefin neat oil (PAO 40) were studied at pure sliding conditions. For this purpose, eight PAO 40 nanodispersions were prepared: four nanodispersions with h-BN and four others based on GnP. The mass concentrations of these dispersions are 0.25, 0.50, 0.75 and 1.00 wt% of h-BN and 0.05, 0.10. 0.25 and 0.50 wt% of GnP, having all of them a good stability against sedimentation (at least 96 h). Tribological assays were carried with prepared nanolubricants as well as with PAO 40 base oil at 20 N load. All nanolubricants based on h-BN or GnP showed lower friction coefficients in comparison to the non-additivated neat oil, with a maximum decrease in friction of 21% for the 0.50 wt% GnP nanodispersion. Regarding the produced wear, all disks lubricated with nanolubricants showed lower wear than those lubricated using PAO 40. The greatest wear reduction in wear track width (22%) was also achieved for the 0.50 wt% in GnP nanolubricant. Moreover, through the confocal Raman microscopy and roughness analyses of worn disks it can be concluded that the wear reductions are due to the surface repairing and tribofilm formation mechanisms.

Enhanced Crystallinity and Luminescence Characteristics of Hexagonal Boron Nitride Doped with Cerium Ions According to Tempering Temperatures.

Hexagonal boron nitride was synthesized by pyrolysis using boric acid and melamine. At this time, to impart luminescence, rare earth cerium ions were added to synthesize hexagonal boron nitride nanophosphor particles exhibiting deep blue emission. To investigate the changes in crystallinity and luminescence according to the re-heating temperature, samples which had been subjected to pyrolysis at 900 °C were subjected to re-heating from 1100 °C to 1400 °C. Crystallinity and luminescence were enhanced according to changes in the reheating temperature. The synthesized cerium ion-doped hexagonal boron nitride nanoparticle phosphor was applied to the anti-counterfeiting field to prepare an ink that can only be identified under UV light.

An exergy analysis of a concentric tube heat exchanger using hBN-water nanofluids

This study investigated the effects of using nanofluids prepared with hexagonal boron nitride (hBN) nanoparticles on the thermal performance and pressure drop of a concentric tube heat exchanger. Experiments were carried out with water-hBN nanofluids for stable, dispersed, 0.01%, 0.1% and 1% volume concentrations, at different flow rates and Reynolds numbers under parallel and counter-flow conditions. When the experimental results were examined, the exergy loss was higher in the parallel-flow heat exchanger compared to the counter-flow heat exchanger. The highest exergy loss value was obtained for distilled water at the highest Reynolds number (Re = 8,700) for parallel flow operation at 170 W. The exergy loss of water at the highest Reynolds number (Re = 8,700) for parallel flow operation increased by 15.7%, 24.8% and 49.8% for hBN-water concentrations of 0.01%, 0.1% and 1%, respectively. Exergy loss of water at the highest Reynold number (Re = 8,700) for counter flow operation increased by 11.3%, 17.3% and 29.2% for hBN-water concentrations of 0.01%, 0.1% and 1%, respectively. When evaluating the exergy analysis of the system, exergy losses due to pressure drops were negligible for both flows (parallel and counter).

An exergy analysis of a concentric tube heat exchanger using hBN-water nanofluids

This study investigated the effects of using nanofluids prepared with hexagonal boron nitride (hBN) nanoparticles on the thermal performance and pressure drop of a concentric tube heat exchanger. Experiments were carried out with water-hBN nanofluids for stable, dispersed, 0.01%, 0.1% and 1% volume concentrations, at different flow rates and Reynolds numbers under parallel and counter-flow conditions. When the experimental results were examined, the exergy loss was higher in the parallel-flow heat exchanger compared to the counter-flow heat exchanger. The highest exergy loss value was obtained for distilled water at the highest Reynolds number (Re = 8,700) for parallel flow operation at 170 W. The exergy loss of water at the highest Reynolds number (Re = 8,700) for parallel flow operation increased by 15.7%, 24.8% and 49.8% for hBN-water concentrations of 0.01%, 0.1% and 1%, respectively. Exergy loss of water at the highest Reynold number (Re = 8,700) for counter flow operation increased by 11.3%, 17.3% and 29.2% for hBN-water concentrations of 0.01%, 0.1% and 1%, respectively. When evaluating the exergy analysis of the system, exergy losses due to pressure drops were negligible for both flows (parallel and counter).

Effect of h-BN nanoparticles on the tribological and rheological properties of API-Group I Oils

ABSTRACT The paper investigates the effect of hexagonal boron nitride (h-BN) nanoparticles on the tribological and rheological properties of the API-Group I lubricants i.e. Solvent neutral (SN)-500, Bright Stock (BS)-270, and thirdly a mixture of SN-500 and BS-270. The tribological properties of the base oils and the nanolubricants are studied using a four-ball tester and the experiments are carried out as per ASTM D4172 standard. It is observed that the addition of 0.25 wt.% h-BN nanoparticles improves the tribological properties of base oils. The wear scar diameter reduces by 2.51%, 19.78% and 3.17% for SN-500, BS-270, and BS+SN at 0.25 wt% h-BN nanoparticles concentration respectively. The rheological properties of the lubricants are measured on Anton Paar’s MCR 102. BS-270 depicts the maximum viscosity among the Group I oils equal to 289.14 mPa.s at 40 °C. Further, all the oils depict an increase in the dynamic viscosity with an increase in the concentration of nanoparticles.

Tribological Analyses of Modified Jatropha Oil with hBN and Graphene Nanoparticles as An Alternative Lubricant for Machining Process

The increase of health and environmental consciousness has motivated the effort of technology improvement on lubrication by finding and exploring another potential alternative to replace mineral-based metalworking fluids. Due to this concern, vegetable-based oils have been recognised as an ideal lubricating base oil in machining due to low toxicity, biodegradable, and renewable energy sources. Moreover, nanofluids have attracted enormous attention in the field of lubrication due to excellent physical and chemical properties that can enhance tribological characterisation. The objective of the current work is to develop a new formulation of nanofluids in modified jatropha oil (MJO) by adding hexagonal boron nitride (hBN) and graphene nanoparticle additives at the lowest concentration (0.01, 0.025. and 0.05 wt. %). The physicochemical tests in terms of kinematic viscosity and viscosity index were conducted and compared with synthetic ester (SE). Tribology testing was conducted through four-ball test to determine the coefficient of friction, mean wear scar diameter, and friction torque. The result shows a significant improvement of MJO samples by adding nanoparticle additives compared to the SE. MJOg2 (MJO + 0.025 wt. % of graphene) exhibited excellent tribological behaviour by providing the lowest coefficient of friction and friction torque. Meanwhile, MJOh1 (MJO + 0.01 wt. % of hBN) provided with a smaller mean wear scar diameter among other lubricant samples. Conclusively, the addition of nanoparticle additives significantly enhanced the tribological characteristics and is highly suitable as a substitute for SE.

A Numerical Study on Performance Improvement in Boiling Heat Transfer via Dichloromethane-Based Nanofluid Utilization

Nanofluids are colloidal suspensions and have been utilized frequently in heat transfer implementations ranging from heating to cooling. In this study, for numerically specifying the influence of nanoparticle addition inside the base fluid on pool boiling heat transfer, a series of numerical analysis were performed by using hexagonal boron nitride and dichloromethane as nanoparticle and base fluid material, respectively. The nanofluid solution was prepared by doping hexagonal boron nitride nanoparticles into the dichloromethane at the rate of 1.0% (vol.) and Sodium Dodecyl Benzene Sulfonate was added into this solution to prevent nanoparticle compilation during operation. Computational Fluid Dynamics (CFD) approach was preferred and ANSYS Fluent software was used for numerical analysis. In order to be able to make comparison, analysis was performed both dichloromethane and hexagonal boron nitride nanoparticles containing dichloromethane, i.e. nanofluid, solutions. Vapour volume fractions, velocity vectors and contours for each working fluid were determined and discussed.

The tribological behavior of hybrid aluminum alloy nanocomposites at High temperature: Role of nanoparticles

The influence of the addition of hexagonal boron nitride nanoparticles and silicon carbide nanoparticles on dry sliding tribological properties of the AA2024-SiC-h-BN hybrid nanocomposites was evaluated at high-temperature environment using pin- on- disc wear testing machine at 30, 100, 200 and 300 °C under an applied load of 10, 20, and 30 N. The aluminium alloy 2024 matrix shows mild to rigorous wear at and above 100 °C under an applied load of 10, 20, and 30 N. AA2024–1.5 wt. % of SiC–2 wt. % of h-BN (H3), and AA2024–2 wt. % of SiC–1.5 wt. % of h-BN (H4) hybrid nanocomposites exhibit severe wear only at a 30 °C chamber temperature environment under an applied load of 30 N. The absence of severe wear phenomena in AA2024-SiC-h-BN hybrid nanocomposites is attributed to the formation of thin lubricant film, oxidation layer, and mechanical mixed layer on the pin surface. Abrasive, adhesive, and fracture wear are the main mode of wear mechanism for AA2024-SiC-h-BN hybrid nanocomposites in a high-temperature environmental chamber at 30, 100, 200 and 300 °C under an applied load of 10, 20, and 30 N.

The effect of the ceramic amount on the radiation shielding properties of metal-matrix composite coatings

In this study, Ni-B metal matrix composite coatings reinforced with hexagonal boron nitride (hBN) nanoparticles were fabricated on 304L steel substrate with electrochemical deposition method. The volume fraction of hBN was 6-26%. The phase and morphological characteristics were determined via XRD and FE-SEM, respectively. Ni-B/hBN composite coatings were irradiated with Am-241, Sr-90 and Co-60 radioactive sources, which are typical alpha, beta and gamma-ray sources, respectively. Percent absorption rates were acquired according to the hBN volume fractions of each irradiated sample. Accordingly, it was found that the absorption rates also raised as the volume fractions of the hBN in the coating increased. In order to control the findings, stopping power and range values were procured with SRIM and ESTAR databases. Similar to the absorption rate, increasing volume fractions increased the stopping power and decreased the range values. Nuclear radiation shielding properties of metal matrix composite materials are presented here for the first time. This study revealed the importance of Ni-B/hBN composite coatings in terms of radiation shielding properties.

Effect of Modified Hexagonal Boron Nitride Nanoparticles on the Emulsion Stability, Viscosity and Electrochemical Behavior of Nanostructured Acrylic Coatings for the Corrosion Protection of AISI 304 Stainless Steel

In this study, the effect of pure and modified hexagonal boron nitride (h-BN) nanosheet incorporation on the stability, viscosity, and electrochemical behavior of a waterborne emulsion acrylic coating was studied. The functionalization of h-BN nanoplatelets with polyacrylic acid (PAA) plasma polymerization was performed, and the successful surface modification was determined through water dispersion testing, Fourier transform infrared spectroscopy and thermogravimetric analysis, X-ray photoelectron spectroscopy, and also by transmission electronic microscopy. Later, the stability and viscosity properties of emulsion nanostructured acrylic coatings, which were previously prepared by an ultrasound-assisted mixing system, were analyzed using zeta potential and rheometry testing, respectively. The electrochemical behavior was analyzed by electrochemical impedance spectroscopy. The results prove an effective deposition of PAA films on the h-BN surfaces, which enhanced the stability and viscosity acrylic of nanostructured coatings due to the interactions between the h-BN nanoplatelets surface and emulsion acrylic paint and also with the thickener additives. On the other hand, the electrochemical analysis demonstrated a significant increase (two orders of magnitude) in corrosion resistance in the acrylic nanostructured coatings with 1 wt.% of unmodified and modified h-BN nanoplatelets concerning pure acrylic paint due to a barrier protection mechanism of corrosion inhibition. Therefore, the results demonstrate that the surface modification of h-BN by plasma polymerization (green technology) helped to solve the low dispersibility issue of BN nanosheet surfaces in a waterborne polymer matrix to obtained green nanostructured acrylic coatings with the right balance in in-can properties and corrosion inhibition of AISI 304 stainless steel.

Measurement of roller chain wear lubricated with palm oil-based hexagonal boron nitride nanoparticles

Purpose This study aims to introduce a novel technique which helped in quantifying the wear performance of a roller chain which was lubricated by using the palm oil-based hexagonal boron nitride (hBN) nanoparticles (nano-biolubricant). Design/methodology/approach The efficiency of the nano-biolubricant was evaluated by using a custom-made roller chain tribometer, at different resistance torque values at a constant speed and running time. Prior to the test, 2 different lubrication conditions were applied. The mass loss and elongation behaviour of a roller chain was selected as a degradation metric for monitoring the amount of the chain wear. The predominant wear mechanism of a roller chain was identified by surface morphological analysis. Findings Regardless of the lubrication conditions, the wear performance of the roller chain was significantly increased, at increasing resistance torque values. Higher wear was noted when the roller chain was lubricated using a nano-biolubricant, however, the wear curve showed a promising high chain life. The predominant wear mechanism involved is abrasive wear. Originality/value Although an increase in the elongation during running is based on the wear between the pins and roller, none of the earlier studies quantified the wear performance of a roller chain under differing lubrication conditions. Hence, for bridging the gap, this study described a new method for measuring the wear performance of the roller chain which was lubricated using the palm oil-based hBN nanoparticles or a nano-biolubricant. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-02-2020-0061/

In Vivo Assessment of the Effect of Hexagonal Boron Nitride Nanoparticles on Biochemical, Histopathological, Oxidant and Antioxidant Status

The aim of our study is to investigate the dose-dependent biological system effect of hexagonal boron nitride (hBN) nanoparticles, which is directly produced nanoscale, in vivo. Wistar albino rats (n = 80) weighing 200–250 g were divided into eight groups (n = 10). The acute effects of hBN NPs (i.v) on the rats were investigated by measuring the biochemical, hematological parameters and oxidant-antioxidant status. The results show that no significant change was observed in the hematological and biochemical parameters when the control group and other low dose groups were compared, except for the 1600 and 3200 µg/kg b.w. dose groups. Histological detection indicated that 1600 and 3200 µg/kg hBN NPs treatment could induce significant damage in the liver, kidney, heart, spleen and pancreas. With the findings obtained, it can be seen that hBN NPs cannot be evaluated independently of particle morphology, and that the hBN NPs used in this study may be suitable for biomedical applications where low doses between 50 and 800 µg/kg are not toxic.

Synergistic effects of hexagonal boron nitride nanoparticles and phosphonium ionic liquids as hybrid lubricant additives

Hybrid nanostructure combinations of ionic liquids (ILs) and hexagonal boron nitride (h-BN) nanosheets are proposed as additives to lubricants to enhance their tribological performance and their temporal stability. Trihexyltetradecylphosphonium bis(2-ethylhexyl)phosphate (IL1), tributylethylphosphonium diethylphosphate (IL2) and trihexyltetradecylphosphonium bis(2,4,4-trimethylpentyl)phosphinate (IL3) are the ILs (at 1 wt%) that have been combined, each separately, with h-BN nanosheets (at 0.1 wt%), were added as hybrid additives in a polyalphaolefin base lubricant, PAO 32. Some of the nanodispersions remain stable up to 240 days after preparation. Increases in both viscosity and density owing to h-BN nanoparticles and/or ILs are lower than 7% and 0.3%, respectively. The tribological performance (friction and wear) of the several developed nanolubricants were investigated using a tribometer with a ball-on-three-pin configuration and a 3D optical profiler, respectively. The results showed that the hybrid additives improve, in general, the tribological performance of the lubricant rather than being used separately, thus synergistic effects have been found. Raman spectroscopy conducted on the worm surface showed protective IL and h-BN tribofilms. PAO 32 + IL1 + h-BN is the nanolubricant that exhibits the best tribological performance of those studied in this work.