During the last decade nanoparticles have gained attention as promising drug delivery agents that can transport through the blood brain barrier. Recently, several studies have demonstrated that specifically targeted nanoparticles which carry a large payload of therapeutic agents can effectively enhance therapeutic agent delivery to the brain. However, it is difficult to draw definite design principles across these studies, owing to the differences in material, size, shape and targeting agents of the nanoparticles. Therefore, the main objective of this study is to develop general design principles that link the size of the nanoparticle with the probability to cross the blood brain barrier. Specifically, we investigate the effect of the nanoparticle size on the probability of barbiturate coated GNPs to cross the blood brain barrier by using bEnd.3 brain endothelial cells as an in vitro blood brain barrier model. The results show that GNPs of size 70 nm are optimal for the maximum amount of gold within the brain cells, and that 20 nm GNPs are the optimal size for maximum free surface area. These findings can help understand the effect of particle size on the ability to cross the blood brain barrier through the endothelial cell model, and design nanoparticles for brain imaging/therapy contrast agents.

WS₂ nanotubes functionalized with carboxylic acid functions (WS₂-COOH) were used for improved immobilization of the enzyme tyrosinase in order to form an electrochemical biosensor towards catechol and dopamine. The nanotubes were deposited on glassy carbon electrodes using a dispersion-filtration-transfer procedure to assure the reproducibility of the deposits. After the electrochemical and morphological characterization of these WS₂-COOH nanotube deposits, the formed biosensors showed very satisfying performance towards catechol detection with a linear range of 0.6–70 μmol L⁻¹ and a sensitivity of 10.7 ± 0.2 mA L mol⁻¹. The apparent Michaelis Menten constant of this system is slightly lower than the K_M value of tyrosinase in solution, reflecting an excellent accessibility of the active site of the enzyme combined with a good mass transport of the target molecule through the deposit. For dopamine detection, we observed an accumulation of this substrate due to electrostatic interactions between the amine function of dopamine and the carboxylic acid groups of the nanotubes. This led to improved signal capture at low dopamine concentrations. With linear ranges of 0.5–10 μmol L⁻¹ and 10–40 μmol L⁻¹, and respective sensitivities of 6.2 ± 0.7 mA L mol⁻¹ and 3.4 ± 0.4 mA L mol⁻¹, the overall sensor performance is within the average of comparable results using carbon nanotubes. Nonetheless, the simplified handling of these nanotubes and their reduced environmental impact make these WS₂-COOH nanotubes a promising nanomaterial for biosensing applications.

A simple method for controlling the wettability properties of poly(ethyleneterephthalate) (PET) fibers is reported herein. Silica nanoparticles (silica NPs) and multi-walled carbon nanotubes (MWCNTs) coated on PET fibers altered both the surface roughness and the surface energy of the fibers and endowed the PET fibers with opposite wettability properties. The morphology, composition and wettability of silica NPs and MWCNTs coated PET fibers are detected by a combination of scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) measurements and the wet environmental scanning electron microscopy (ESEM) technique. The possible mechanism and size effect of functional nanomaterials on the wettability property of PET fibers are also discussed.