Non-coordinating anions assemble cyanine amphiphiles into ultra-small fluorescent nanoparticles

A non-coordinating anion, fluorinated tetraphenylborate, assembles specially designed cationic cyanine amphiphiles into 7–8 nm fluorescent nanoparticles that are >40-fold brighter than a single cyanine dye. This kind of anion, combining hydrophobic and electrostatic forces in aqueous media, constitutes promising building blocks in the self-assembly of functional nanomaterials

Highly lipophilic fluorescent dyes in nano-emulsions: towards bright non-leaking nano-droplets

Dye-loaded lipid nano-droplets present an attractive alternative to inorganic nanoparticles, as they are composed of non-toxic biodegradable materials and are easy to prepare. However, to achieve high fluorescence brightness, the nano-droplets have to be heavily loaded with the dyes avoiding fluorescence self-quenching and release (leakage) of the encapsulated dyes from the nano-droplets in biological media. In the present work, we have designed highly lipophilic fluorescent derivatives of 3-alkoxyflavone (F888) and Nile Red (NR668) that can be encapsulated in the lipophilic core of stable nano-emulsion droplets at exceptionally high concentrations in the oil core, i.e. up to 170 mM and 17 mM, respectively, corresponding to ∼830 and 80 dyes per 40 nm droplet. Despite this high loading, these dyes keep high fluorescence quantum yields and thus, provide high nano-droplet brightness, probably due to their bulky structure preventing self-quenching. Moreover, simultaneous encapsulation of both dyes at high concentrations in single nano-droplets allows the observation of FRET. FRET and fluorescence correlation spectroscopy (FCS) studies showed that NR668 release in the serum-containing medium is very slow, while the reference hydrophobic dye Nile Red leaks immediately. This drastic difference in the leakage profile between NR668 and Nile Red was confirmed by in vitro cellular studies as well as by in vivo angiography imaging on zebrafish models, where the NR668-loaded nano-droplets remained in the blood, while the parent Nile Red leaked rapidly from the droplets distributing all over the animal body. This study suggests new molecular design strategies for obtaining bright nano-droplets without dye leakage and their use as efficient and stable optical contrast agents in vitro and in vivo

Tuning color and photostability of perylene diimides inside polymer nanoparticles: towards biodegradable substitutes of quantum dots

International audienc

Surface modification of refractory alloys with high-power pulsed ion-beam treatment and arc-pulsed ion implantation

High-power pulsed ion beam (HPPIB) treatment and arc-pulsed ion implantation (APII) were combined consecutively to be the improvement of service properties of high temperature refractory alloys. The influence of this combined processing on the physical and chemical state of refractory alloy surface layers was studied. It is shown that it is possible to combine the positive effects of each technology in order to obtain an ideal smooth surface (without craters, Ra =0.06-0.10 pm) and to increase the alloyed surface layer thickness due to irradiation-enhanced diffusion. Consequently, the positive effect of this combined treatment on the fatigue strength, salt corrosion resistance, and oxidation resistance is connected with the following processes: smoothing of a surface microrelief; high-speed-solidification; surface alloying; structure stabilization during a post-process vacuum annealing

Squaraine as a bright, stable and environment-sensitive far-red label for receptor-specific cellular imaging.

International audienc