Synthesis of boron nitride nanotubes and their applications

A new strategy for making a sensitive sensor for aspirin drug: first-principles investigations by using pure and metal-doped BN nano-heterostructures

The present study used the DFT method to investigate aspirin's intermolecular interactions with boron nitride (BN) nanotubes modified with aluminum, gallium, and zinc. Our experiments obtained adsorption energy of -40.4 kJ/mol for aspirin on BN nanotubes. By doping each of the above metals on the surface of the BN nanotube, the aspirin adsorption energy increased dramatically. For BN nanotubes doped with Al, Ga, and Zn, this energy was -255, -251, and -250 kJ/mol. Thermodynamic analyses proved that all surface adsorptions are exothermic and spontaneous. Nanotubes' electronic structures and dipole moments have been examined following aspirin adsorption. In addition, AIM analysis has been performed for all systems in order to understand how the links were formed. According to the obtained results, BN nanotubes doped with metals, as mentioned previously, have a very high electron sensitivity to aspirin. These nanotubes can therefore be used to manufacture aspirin-sensitive electrochemical sensors.Communicated by Ramaswamy H. Sarma.

Boron nitride decorated poly(vinyl alcohol)/poly(acrylic acid) composite nanofibers: A promising material for biomedical applications

In this study, polyvinyl alcohol (PVA) and polyacrylic acid (PAA) nanofibers loaded with boron nitride nanoparticles (mBN) were fabricated by using electrospinning and crosslinked by heat treatment. The physical, chemical, and mechanical properties, hydrophilic behavior, and degradability of composite nanofibers were evaluated. The mechanical properties such as elastic modulus, elongation percentage at the break, and mechanical strength of PVA/PAA nanofibers improved with mBN loading. The thermal conductivity of composite nanofibers reached 0.12 W/m·K at mBN content of 1.0 wt% due to the continuous heat conduction pathways of mBN. In the meantime, while there was no cytotoxicity recorded for both L929 and HUVEC cell lines for all composite nanofibers, the antimicrobial efficiency improved with the incorporation of mBN compared with PVA/PAA and recorded as 68.8% and 75.1% for Escherichia coli and Staphylococcus aureus, respectively. On this basis, the present work proposes a promising biomaterial for biomedical applications such as dual drug delivery, particularly including both hydrophobic and hydrophilic drugs or wound dressing.

Elimination of Cancer Cells in Co-Culture: Role of Different Nanocarriers in Regulation of CD47 and Calreticulin-Induced Phagocytosis

Under healthy conditions, pro- and anti-phagocytic signals are balanced. Cluster of Differentiation 47 (CD47) is believed to act as an anti-phagocytic marker that is highly expressed on multiple types of human cancer cells including acute myeloid leukemia (AML) and lung and liver carcinomas, allowing them to escape phagocytosis by macrophages. Downregulating CD47 on cancer cells discloses calreticulin (CRT) to macrophages and recovers their phagocytic activity. Herein, we postulate that using a modified graphene oxide (GO) carrier to deliver small interfering RNA (siRNA) CD47 (CD47_siRNA) in AML, A549 lung, and HepG2 liver cancer cells in co-culture in vitro will silence CD47 and flag cancer cells for CRT-mediated phagocytosis. Results showed a high knockdown efficiency of CD47 and a significant increase in CRT levels simultaneously by using GO formulation as carriers in all used cancer cell lines. The presence of CRT on cancer cells was significantly higher than levels before knockdown of CD47 and was required to achieve phagocytosis in co-culture with human macrophages. Lipid nanoparticles (LNPs) and modified boron nitride nanotubes (BNPs) were used to carry CD47_siRNA, and the knockdown efficiency values of CD47 were compared in three cancer cells in co-culture, with an achieved knockdown efficiency of >95% using LNPs as carriers. Interestingly, the high efficiency of CD47 knockdown was obtained by using the LNPs and BNP carriers; however, an increase in CRT levels on cancer cells was not required for phagocytosis to happen in co-culture with human macrophages, indicating other pathways' involvement in the phagocytosis process. These findings highlight the roles of 2D (graphene oxide), 1D (boron nitride nanotube), and "0D" (lipid nanoparticle) carriers for the delivery of siRNA to eliminate cancer cells in co-culture, likely through different phagocytosis pathways in multiple types of human cancer cells. Moreover, these results provide an explanation of immune therapies that target CD47 and the potential use of these carriers in screening drugs for such therapies in vitro.

LED-light-activated photocatalytic performance of metal-free carbon-modified hexagonal boron nitride towards degradation of methylene blue and phenol

The present study outlines the transformation of non-photoresponsive hexagonal boron nitride (HBN) into a visible-light-responsive material. The carbon modification was achieved through a solid-state reaction procedure inside a tube furnace under nitrogen atmosphere. In comparison to HBN (bandgap of 5.2 eV), the carbon-modified boron nitride could efficiently absorb LED light irradiation with a light harvesting efficiency of ≈90% and a direct bandgap of 2 eV. The introduction of carbon into the HBN lattice led to a significant change in the electronic environment through the formation of C-B and C-N bonds which resulted in improved visible light activity, lower charge transfer resistance, and improved charge carrier density (2.97 × 10¹⁹ cm^-3). This subsequently enhanced the photocurrent density (three times) and decreased the photovoltage decay time (two times) in comparison to those of HBN. The electronic band structure (obtained through Mott-Schottky plots) and charge trapping analysis confirmed the dominance of e^-, O₂ ^-•, and ^•OH as dominant reactive oxygen species. The carbon modification could effectively remove 93.83% of methylene blue (MB, 20 ppm solution) and 48.56% of phenol (10 ppm solution) from the aqueous phase in comparison to HBN which shows zero activity in the visible region.

Prediction of the electronic structure of single-walled GeS nanotubes

The structure and electronic properties of puckered GeS nanotubes have been investigated using first-principles density functional theory calculation. Our results show that both the armchair and zigzag GeS nanotubes are semiconductor materials with an adjustable band gap. The band gap increases gradually with increasing the tube diameter, and slowly converges to the monolayer limit. On the application of strain, the GeS nanotubes provide interesting strain-induced band gap variation. When the compressive strain reached 20%, zigzag GeS nanotubes are completely transformed into armchair GeS nanotubes. In addition, the elastic properties of the relatively stable armchair GeS nanotubes have been studied, the Young's modulus of the armchair (11, 11), (13, 13) and (15, 15) nanotubes were calculated to be 227.488 GPa, 211.888 GPa and 213.920 GPa, respectively. Our work confirms that compared with carbon nanotubes, two-dimensional materials with a puckered structure are easier to realize phase transition by stress.

Piezoelectric Electrospun Fibrous Scaffolds for Bone, Articular Cartilage and Osteochondral Tissue Engineering

Osteochondral tissue (OCT) related diseases, particularly osteoarthritis, number among the most prevalent in the adult population worldwide. However, no satisfactory clinical treatments have been developed to date to resolve this unmet medical issue. Osteochondral tissue engineering (OCTE) strategies involving the fabrication of OCT-mimicking scaffold structures capable of replacing damaged tissue and promoting its regeneration are currently under development. While the piezoelectric properties of the OCT have been extensively reported in different studies, they keep being neglected in the design of novel OCT scaffolds, which focus primarily on the tissue’s structural and mechanical properties. Given the promising potential of piezoelectric electrospun scaffolds capable of both recapitulating the piezoelectric nature of the tissue’s fibrous ECM and of providing a platform for electrical and mechanical stimulation to promote the regeneration of damaged OCT, the present review aims to examine the current state of the art of these electroactive smart scaffolds in OCTE strategies. A summary of the piezoelectric properties of the different regions of the OCT and an overview of the main piezoelectric biomaterials applied in OCTE applications are presented. Some recent examples of piezoelectric electrospun scaffolds developed for potentially replacing damaged OCT as well as for the bone or articular cartilage segments of this interfacial tissue are summarized. Finally, the current challenges and future perspectives concerning the use of piezoelectric electrospun scaffolds in OCT regeneration are discussed.

Fabrication and Characterization of Human Serum Albumin Particles Loaded with Non-Sericin Extract Obtained from Silk Cocoon as a Carrier System for Hydrophobic Substances

Non-sericin (NS) extract was produced from the ethanolic extract of Bombyx mori silk cocoons. This extract is composed of both carotenoids and flavonoids. Many of these compounds are composed of substances of poor aqueous solubility. Thus, this study focused on the development of a carrier system created from biocompatible and biodegradable materials to improve the biological activity of NS extracts. Accordingly, NS was incorporated into human serum albumin template particles with MnCO₃ (NS-HSA MPs) by loading NS into the preformed HAS-MnCO₃ microparticles using the coprecipitation crosslinking dissolution technique (CCD-technique). After crosslinking and template dissolution steps, the NS loaded HSA particles are negatively charged, have a size ranging from 0.8 to 0.9 µm, and are peanut shaped. The degree of encapsulation efficiency ranged from 7% to 57% depending on the initial NS concentration and the steps of adsorption. In addition, NS-HSA MPs were taken up by human lung adenocarcinoma (A549 cell) for 24 h. The promotion of cellular uptake was evaluated by flow cytometry and the results produced 99% fluorescent stained cells. Moreover, the results from CLSM and 3D fluorescence imaging confirmed particle localization in the cells. Interestingly, NS-HSA MPs could not induce inflammation through nitric oxide production from macrophage RAW264.7 cells. This is the first study involving the loading of non-sericin extracts into HSA MPs by CCD technique to enhance the bioavailability and biological effects of NS. Therefore, HSA MPs could be utilized as a carrier system for hydrophobic substances targeting cells with albumin receptors.

Investigation of nanotubes as the smart carriers for targeted delivery of mercaptopurine anticancer drug

Mercaptopurine (MCP) is an anticancer drug that is used to treat acute lymphoblastic leukemia. The therapeutic effect of the mercaptopurine limits its severe side effects like other cytotoxic (anti-cancer) drugs. Nanostructures or nanoparticles can be widely used as potential drug carriers for diagnosis and treatment of cancer. In the current study, the boron nitride nanotube (BNNT) and carbon nanotube (CNT) were studied as the delivery carriers of MCP using the density functional theory (DFT) calculations and molecular dynamics (MDs) simulation studies. To further understand the electronic properties of mercaptopurine, the partial density of states (PDOS) was calculated. The PDOS results depicted that the electronic features of the MCP do not change after the adsorption on the surface of the nanotubes. More stability of the MCP/BNNT complexes may be attributed to the existence of the intermolecular hydrogen bonds (H-bonds) between the hydrogen atoms of the MCP molecule and the N atoms of the BNNT. The results of the quantum theory of atoms in molecules (QTAIM) confirmed the presence of H-bonds in these complexes. Moreover, MD simulation studies were done in the presence of five drug molecules. The results revealed that the strongest van der Waals (vdW) interaction energy was found between the BNNT and MCP among the studied nanotubes, indicating the BNNT is a better nanocarrier than carbon nanotube for delivery of the MCP drug within the biological systems. In general, the obtained results may present helpful information on the nature of the interactions between mercaptopurine anticancer drug with BNNT and/or CNT.Communicated by Ramaswamy H. Sarma.

Ecotoxicological assessment of commercial boron nitride nanotubes toward Xenopus laevis tadpoles and host-associated gut microbiota

Despite the growing interest for boron nitride nanotubes (BNNT) due to their unique properties, data on the evaluation of the environmental risk potential of this emerging engineered nanomaterial are currently lacking. Therefore, the ecotoxicity of a commercial form of BNNT (containing tubes, hexagonal-boron nitride, and boron) was assessed in vivo toward larvae of the amphibian Xenopus laevis. Following the exposure, multiple endpoints were measured in the tadpoles as well as in bacterial communities associated to the host gut. Exposure to BNNT led to boron accumulation in host tissues and was not associated to genotoxic effects. However, the growth of the tadpoles increased due to BNNT exposure. This parameter was associated to remodeling of gut microbiome, benefiting to taxa from the phylum Bacteroidetes. Changes in relative abundance of this phylum were positively correlated to larval growth. The obtained results support the finding that BNNT are biocompatible as indicated by the absence of toxic effect from the tested nanomaterials. In addition, byproducts, especially free boron present in the tested product, were overall beneficial for the metabolism of the tadpoles.

A review on nanotoxicity and nanogenotoxicity of different shapes of nanomaterials

Nanomaterials (NMs) generally display fascinating physical and chemical properties that are not always present in bulk materials; therefore, any modification to their size, shape, or coating tends to cause significant changes in their chemical/physical and biological characteristics. The dramatic increase in efforts to use NMs renders the risk assessment of their toxicity highly crucial due to the possible health perils of this relatively uncharted territory. The different sizes and shapes of the nanoparticles are known to have an impact on organisms and an important place in clinical applications. The shape of nanoparticles, namely, whether they are rods, wires, or spheres, is a particularly critical parameter to affect cell uptake and site-specific drug delivery, representing a significant factor in determining the potency and magnitude of the effect. This review, therefore, intends to offer a picture of research into the toxicity of different shapes (nanorods, nanowires, and nanospheres) of NMs to in vitro and in vivo models, presenting an in-depth analysis of health risks associated with exposure to such nanostructures and benefits achieved by using certain model organisms in genotoxicity testing. Nanotoxicity experiments use various models and tests, such as cell cultures, cores, shells, and coating materials. This review article also attempts to raise awareness about practical applications of NMs in different shapes in biology, to evaluate their potential genotoxicity, and to suggest approaches to explain underlying mechanisms of their toxicity and genotoxicity depending on nanoparticle shape.

Nanocomposite Membranes for Liquid and Gas Separations from the Perspective of Nanostructure Dimensions

One of the critical aspects in the design of nanocomposite membrane is the selection of a well-matched pair of nanomaterials and a polymer matrix that suits their intended application. By making use of the fascinating flexibility of nanoscale materials, the functionalities of the resultant nanocomposite membranes can be tailored. The unique features demonstrated by nanomaterials are closely related to their dimensions, hence a greater attention is deserved for this critical aspect. Recognizing the impressive research efforts devoted to fine-tuning the nanocomposite membranes for a broad range of applications including gas and liquid separation, this review intends to discuss the selection criteria of nanostructured materials from the perspective of their dimensions for the production of high-performing nanocomposite membranes. Based on their dimension classifications, an overview of the characteristics of nanomaterials used for the development of nanocomposite membranes is presented. The advantages and roles of these nanomaterials in advancing the performance of the resultant nanocomposite membranes for gas and liquid separation are reviewed. By highlighting the importance of dimensions of nanomaterials that account for their intriguing structural and physical properties, the potential of these nanomaterials in the development of nanocomposite membranes can be fully harnessed.

Hybrid Ni-Boron Nitride Nanotube Magnetic Semiconductor-A New Material for Spintronics

Here, we report the presence of ferromagnetism in hybrid nickel-boron nitride nanotubes (BNNTs) with an ordered structure, synthesized by chemical vapor deposition using elemental boron, nickel oxide as the catalyst, and ammonia gas as the source for nitrogen. In previous studies, the nanotubes were synthesized with two metal oxide catalysts, whereas here, only a single catalyst was used. The nanotube's structure was determined by X-ray diffraction, scanning electron microscopy, and high-resolution transmission electron microscopy. Purity of the nanotubes synthesized at 1150 °C was exceptional and this was determined by Raman spectroscopy. The average diameter of the nanotubes was 63 nm. Based on the magnetic studies carried out, it can be confirmed that the synthesized hybrid material is ferromagnetic at room temperature. Cyclic voltammetry was carried out to confirm the dielectric nature of the nanotubes. These materials could pave ways to nanoscale devices. The well-known thermal stability of BNNTs would play a vital role in preventing thermal failures in such small-scale devices where overheating is a major concern. The presence of semiconducting and magnetic properties in a single material could be confirmed, which might be highly significant in the field of spintronics.

Single- and double-walled boron nitride nanotubes: Controlled synthesis and application for water purification

Research interest in boron nitride nanotubes (BNNTs) has increased after the recent success of large-scale BNNT syntheses using high-temperature-pressure laser ablation or high-temperature plasma methods. Nonetheless, there are limits to the application and commercialization of these materials because of the difficulties associated with their fine structural control. Herein, the growth kinetics of BNNTs were systemically studied for this purpose. The growth pressure of the nitrogen feed gas was varied while the growth temperature remained constant, which was confirmed by black body radiation measurements and calculations based on a heat loss model. Changing from the diffusion-limited regime to the supply-limited regime of growth kinetics based on the optimized BNNT synthesis condition afforded the control of the number of BNNT walls. The total amount of BNNTs possessing single and double walls was over 70%, and the BNNT surface area increased to 278.2 m²/g corresponding to small wall numbers and diameters. Taking advantage of the large surface area and high-temperature durability of the material, BNNTs utilized as a recyclable adsorbent for water purification. The efficiency of the BNNTs for capturing methylene blue particles in water was approximately 94%, even after three repetition cycles, showing the potential of the material for application in the filter industry.

BAs nanotubes with non-circular cross section shapes for gas sensors

Electronic transport properties of circular and elliptical BAs nanotubes before and after encapsulation of water.

pH-Controlled fluorescence switching in water-dispersed polymer brushes grafted to modified boron nitride nanotubes for cellular imaging

pH-Switchable, fluorescent, hybrid, water-dispersible nanomaterials based on boron nitride nanotubes (BNNTs) and grafted copolymer brushes (poly(acrylic acid-co-fluorescein acrylate) - P(AA-co-FA)) were successfully fabricated in a two-step process. The functionalization of BNNTs was confirmed by spectroscopic, gravimetric and imaging techniques. In contrast to "pure" BNNTs, P(AA-co-FA)-functionalized BNNTs demonstrate intense green fluorescence emission at 520 nm. Under neutral or alkaline pH values, P(AA-co-FA)-functionalized BNNTs are highly emissive in contrast to acidic pH conditions where the fluorescent intensity is absent or low. No increase in the absorption was observed when the suspension pH was increased from 7 to 10. The functionalized BNNTs are easily taken up by human normal prostate epithelium (PNT1A) and human prostate cancer cell lines (DU145) and are suitable for further evaluation in cellular imaging applications.

Dynamic thin film mediated slicing of boron nitride nanotubes

A method has been developed to slice boron nitride nanotubes BNNTs under continuous flow in a vortex fluidic device (VFD), along with a method to partially purify the as received BNNT containing material. The latter involves heating the BNNTs to 600 °C followed by dispersing in a 1 : 3 isopropyl alcohol (IPA) and water mixture at 100 °C. The VFD mediated slicing of the BNNTs comprises irradiating the rapidly rotating glass tube (20 mm OD) with a pulsed Nd:YAG laser. Systematically exploring the operating parameter space of the VFD established slicing of ca. 200 μm long purified BNNTs down to 340 nm to 400 nm, in ca. 53% yield, in a 1 : 1 mixture of IPA and water, in the absence of reagents/harsh chemicals, at a flow rate of 0.45 mL min^-1, a concentration of 0.1 mg mL^-1 BNNTs and an 8.5k rpm rotational speed, with the pulsed laser operating at 1064 nm and 250 mJ per pulse.

A computational study on the electronic and optical properties of boron-nitride circumacenes

We report a comparative and systematic computational analysis on the electronic and optical properties of the boron-nitride-made (BN) counterparts of the carbon-made circumacenes. Recently, these planar molecules have attracted interest for applications in the condensed matter physics domain. In particular, we focus on the five first members of this BN-family (from BN-coronene to BN-circumpentacene) presenting a comparison with their carbon analogues. For all the systems investigated, we calculate different electronic properties and the optical absorption spectra, performing all electron Density Functional Theory (DFT) and Time Dependent-DFT (TD-DFT) calculations. In the context of ab initio calculations we select a localized Gaussian basis-set matched with a hybrid exchange-correlation functional. We discuss possible implications of the observed BN cluster properties, which could be an alternative material or complementar as compared to their carbon analogues. In particular, concerning the optical properties, we have found that the main difference between the two families is that the BN molecules absorb in the UV, rather than in the visible as happens for the C-made parents. Moreover, we demonstrate that the electronic and optical observables of the BN clusters are nearly independent of the cluster size in contrast to what happens for their carbonaceous counterparts.

Highly Compressive Boron Nitride Nanotube Aerogels Reinforced with Reduced Graphene Oxide

Boron nitride nanotubes (BNNTs), structural analogues of carbon nanotubes, have attracted significant attention due to their superb thermal conductivity, wide bandgap, excellent hydrogen storage capacity, and thermal and chemical stability. Despite considerable progress in the preparation and surface functionalization of BNNTs, it remains a challenge to assemble one-dimensional BNNTs into three-dimensional (3D) architectures (such as aerogels) for practical applications. Here, we report a highly compressive BNNT aerogel reinforced with reduced graphene oxide (rGO) fabricated using a freeze-drying method. The reinforcement effect of rGO and 3D honeycomb-like framework offer the BNNTs/rGO aerogel with a high compression resilience. The BNNTs/rGO aerogels were then infiltrated with polyethylene glycol to prepare a kind of phase change materials. The prepared phase change material composites show zero leakage even at 100 °C and enhanced thermal conductivity, due to the 3D porous structure of the BNNTs/rGO aerogel. This work provides a simple method for the preparation of 3D BNNTs/rGO aerogels for many potential applications, such as high-performance polymer composites.

Advances in Halloysite Nanotubes-Polysaccharide Nanocomposite Preparation and Applications

Halloysite nanotubes (HNTs), novel 1D natural materials with a unique tubular nanostructure, large aspect ratio, biocompatibility, and high mechanical strength, are promising nanofillers to improve the properties of polymers. In this review, we summarize the recent progress toward the development of polysaccharide-HNTs composites, paying attention to the main existence forms and wastewater treatment application particularly. The purification of HNTs and fabrication of the composites are discussed first. Polysaccharides, such as alginate, chitosan, starch, and cellulose, reinforced with HNTs show improved mechanical, thermal, and swelling properties. Finally, we summarize the unique characteristics of polysaccharide-HNTs composites and review the recent development of the practical applications.

Antibacterial and Remineralizing Fillers in Experimental Orthodontic Adhesives

Orthodontic adhesives with antimicrobial and remineralizing properties may be an alternative to control white spot lesions around brackets. The aim of this study is to develop an experimental orthodontic adhesive containing boron nitride nanotubes (BNNT) and alkyl trimethyl ammonium bromide (ATAB). Methacrylate (BisGMA and TEGDMA) monomers were used to formulate the adhesives. Four experimental groups were produced with the addition of 0.1 wt.% BNNT (G_BNNT); 0.1 wt.% ATAB (G_ATAB); and 0.2 wt.% BNNT with ATAB (G_BNNT/ATAB); in the control group, no fillers were added (G_Ctrl). The degree of conversion, cytotoxicity, softening in solvent, contact angle and free surface energy, antibacterial activity, shear bond strength, and mineral deposition were evaluated. Adhesives achieved degree of conversion higher than 50% and cell viability higher than 90%. G_BNNT and G_ATAB adhesives exhibited reduced softening in solvent. Mean free surface energy was decreased in the G_BNNT adhesive. Significant reduction in bacterial growth was observed in the G_BNNT/ATAB. No statistical difference was found for shear bond strength. Mineral deposition was found in G_BNNT, G_ATAB, and G_BNNT/ATAB groups after 14 and 28 days. The addition of 0.2% BNNT/ATAB to an experimental orthodontic adhesive inhibited bacterial growth and induced mineral deposition without affecting the properties of the material.

Fabrication and application of BN nanoparticles, nanosheets and their nanohybrids

Smart implementation of novel advanced nanomaterials is the key for the solution of many complex problems of modern science. In recent years, there has been a great interest in the synthesis and application of boron nitride (BN) nanotubes because of their unique physical, chemical, and mechanical properties. By contrast, the synthesis, characterization and exploration of other morphological types of BN nanostructure - BN nanoparticles and BN nanosheets - have received less attention. However, the detailed investigations on advantages of every morphological BN type for specific applications have only recently been started. One of the promising directions is the utilization of BN-based nanohybrids. This review is dedicated to the in-depth analysis of recently published works on the fabrication and application of BN nanoparticles, nanosheets, and their nanohybrids. It covers a variety of developed synthetic methods toward fabrication of such nanostructures, and their specific application potentials in catalysis, drug delivery, tribology and structural materials. Finally, the review focuses on the theoretical aspects of this quickly emerging field.

One-Step Synthesis of Hexagonal Boron Nitrides, Their Crystallinity and Biodegradation

Hexagonal boron nitrides (hBNs) have recently been investigated for several novel applications due to their unique properties such as biocompatibility, superhydrophobicity, electrical insulation, and thermal and chemical stability. In addition, their biodegradation products have recently reported to have therapeutic effect on certain cancer types. hBNs are easily synthesized from boron and nitrogen precursors at moderately low temperatures. However, crystallinity and yield vary depending on the type of precursor, reaction temperature, and duration. In this study, a simple one-step hBNs synthesis method is reported without a catalyst, which might be an undesired contaminant for biomedical applications. The influence of boron precursors (boric acid, colemanite, or boron trioxide) on hBNs crystallinity, stability, and biodegradation in suspensions containing oxidative and hydrolytic degradation agents is investigated with the aim of their possible application in biomedicine. We found that the choice of boron precursor is a critically important parameter controlling the hBNs crystallinity and dependently influencing the biodegradation rate.

Alignment of Boron Nitride Nanofibers in Epoxy Composite Films for Thermal Conductivity and Dielectric Breakdown Strength Improvement

Development of polymer-based composites with simultaneously high thermal conductivity and breakdown strength has attracted considerable attention owing to their important applications in both electronic and electric industries. In this work, boron nitride (BN) nanofibers (BNNF) are successfully prepared as fillers, which are used for epoxy composites. In addition, the BNNF in epoxy composites are aligned by using a film casting method. The composites show enhanced thermal conductivity and dielectric breakdown strength. For instance, after doping with BNNF of 2 wt%, the thermal conductivity of composites increased by 36.4% in comparison with that of the epoxy matrix. Meanwhile, the breakdown strength of the composite with 1 wt% BNNF is 122.9 kV/mm, which increased by 6.8% more than that of neat epoxy (115.1 kV/mm). Moreover, the composites have maintained a low dielectric constant and alternating current conductivity among the range of full frequency, and show a higher thermal decomposition temperature and glass-transition temperature. The composites with aligning BNNF have wide application prospects in electronic packaging material and printed circuit boards.

Nanocomposites based on tubular and onion nanostructures of molybdenum and tungsten disulfides: inorganic design, functional properties and applications

The review concerns the development and the state-of-the-art in studies on the surface modification methods aimed at fabricating promising nanocomposites based on multilayer inorganic tubular and onion (fullerene-like) MoS2 and WS2 nanostructures. The synthetic details and structural features of these materials are considered. Considerable attention is paid to targeted functionalization of molybdenum and tungsten disulfide nanostructures and to fundamental principles that underlie their ability to chemical interactions. The functional properties and applications of the obtained materials are described.

The bibliography includes 183 references.

Boron nitride nanotubes for gene silencing

BACKGROUND

Non-viral gene delivery is increasingly investigated as an alternative to viral vectors due to low toxicity and immunogenicity, easy preparation, tissue specificity, and ability to transfer larger sizes of genes.

METHODS

In this study, boron nitride nanotubes (BNNTs) are functionalized with oligonucleotides (oligo-BNNTs). The morpholinos complementary to the oligonucleotides attached to the BNNTs (morpholino/oligo-BNNTs) are hybridized to silence the luciferase gene. The morpholino/oligo-BNNTs conjugates are administered to luciferase-expressing cells (MDA-MB-231-luc2) and the luciferase activity is monitored.

RESULTS

The luciferase activity is decreased when MDA-MB-231-luc2 cells were treated with morpholino/oligo-BNNTs.

CONCLUSIONS

The study suggests that BNNTs can be used as a potential vector to transfect cells.

GENERAL SIGNIFICANCE

BNNTs are potential new nanocarriers for gene delivery applications.