3 research outputs found
Крещение Крыма
Цель статьи - определить место и значение фестивной культуры в условиях социальных трансформаций
Colloidal CdSe/CdS Dot-in-Plate Nanocrystals with 2D-Polarized Emission
We report the synthesis and properties of a novel class of nanocrystals with mixed dimensionality: a dot-in-plate core/shell nanostructure. This system was synthesized by growing a flat, disk-shaped, CdS shell on spherical CdSe cores. The anisotropic pressure induced by the shell drastically splits the first exciton fine structure in two: the “heavy hole” and “light hole” states become separated by up to 65 meV. As a result, these nanocrystals exhibit an emission strongly polarized in two dimensions, in the plane perpendicular to the wurtzite crystal <i>c</i> axis. We use polarization measurements on single nanocrystals and ensemble anisotropy studies to confirm the nature and position of the excitonic energy levels. These nanocrystals orient spontaneously when evaporated on a substrate, enabling a precise control of the orientation of their emission dipole
Highly Enhanced Affinity of Multidentate versus Bidentate Zwitterionic Ligands for Long-Term Quantum Dot Bioimaging
High colloidal stability in aqueous conditions is a prerequisite
for fluorescent nanocrystals, otherwise known as “quantum dots”,
intended to be used in any long-term bioimaging experiment. This essential
property implies a strong affinity between the nanoparticles themselves
and the ligands they are coated with. To further improve the properties
of the bidentate monozwitterionic ligand previously developed in our
team, we synthesized a multidentate polyzwitterionic ligand, issued
from the copolymerization of a bidentate monomer and a monozwitterionic
one. The nanocrystals passivated by this polymeric ligand showed an
exceptional colloidal stability, regardless of the medium conditions
(pH, salinity, dilution, and biological environment), and we demonstrated
the affinity of the polymer exceeded by 3 orders of magnitude that
of the bidentate ligand (desorption rates assessed by a competition
experiment). The synthesis of the multidentate polyzwitterionic ligand
proved also to be easily tunable and allowed facile functionalization
of the corresponding quantum dots, which led to successful specific
biomolecules targeting