Maho Yamaguchi

Boron nitride nanotubes functionalized with mesoporous silica for intracellular delivery of chemotherapy drugs.

Boron nitride nanotube (BNNT)@mesoporous silica hybrids with controllable surface zeta potential were fabricated for intracellular delivery of doxorubicin. The materials showed higher suspension ability, doxorubicin intracellular endocytosis efficiency, and LNcap prostate cancer cell killing ability compared with naked BNNTs.

Cytocompatibility evaluation of gum Arabic-coated ultra-pure boron nitride nanotubes on human cells

AIM Boron nitride nanotubes (BNNTs) are tubular nanoparticles with a structure analogous to that of carbon nanotubes, but with B and N atoms that completely replace the C atoms. Many favorable results indicate BNNTs as safe nanomaterials; however, important concerns have recently been raised about ultra-pure, long (~10 µm) BNNTs tested on several cell types. MATERIALS & METHODS Here, we propose additional experiments with the same BNNTs, but shortened (~1.5 µm) with a homogenization/sonication treatment that allows for their dispersion in gum Arabic aqueous solutions. Obtained BNNTs are tested on human endothelial and neuron-like cells with several independent biocompatibility assays. Moreover, for the first time, their strong sum-frequency generation signal is exploited to assess the cellular uptake. RESULTS & CONCLUSION Our data demonstrate no toxic effects up to concentrations of 20 µg/ml, once more confirming biosafety of BNNTs, and again highlighting that nanoparticle aspect ratio plays a key role in the biocompatibility evaluation.

Boron nitride nanotube‐enhanced osteogenic differentiation of mesenchymal stem cells

The interaction between boron nitride nanotubes (BNNTs) layer and mesenchymal stem cells (MSCs) is evaluated for the first time in this study. BNNTs layer supports the attachment and growth of MSCs and exhibits good biocompatibility with MSCs. BNNTs show high protein adsorption ability, promote the proliferation of MSCs and increase the secretion of total protein by MSCs. Especially, BNNTs enhance the alkaline phosphatase (ALP) activity as an early marker of osteoblasts, ALP/total protein and osteocalcin (OCN) as a late marker of osteogenic differentiation, which shows that BNNTs can enhance osteogenesis of MSCs. The release of trace boron and the stress on cells exerted by BNNTs with a fiber structure may account for the enhanced differentiation of MSCs into osteoblasts. Therefore BNNTs are potentially useful for bone regeneration in orthopedic applications.

Length Fractionation of Boron Nitride Nanotubes Using Creamed Oil- in-Water Emulsions

The fractionation by length of multiwalled boron nitride nanotubes (BNNTs) was achieved by emulsification and creaming of an oil/water/surfactant mixture. The length separation is based on the fact that nanoparticle-coated oil droplets polydisperse in size move toward the upper surface or the bottom of an emulsified mixture depending on the density of the droplets, such that droplets of different sizes are located at different heights. By sampling heightwise an unstable hexane/water/Tween 20/BNNT (1-20 μm long) emulsion, we observed that the lengths of the BNNTs adsorbed on the droplets display a strong correlation with the droplets sizes, thus leading to selective separation of the BNNT lengths, as confirmed by dark-field optical imaging and dynamic light scattering. This method may potentially be extended to other high aspect ratio nanomaterials exhibiting emulsification properties similar to those of BNNTs.