4 research outputs found
Unusually High Efficiency of β‑Cyclodextrin Clathrate Preparation by Water-Free Solid-Phase Guest Exchange
An effective preparation procedure
is offered for β-cyclodextrin
(bCD) clathrates with volatile guests of moderate hydrophilicity,
which otherwise require a finely tuned optimization of the bCD/water/guest
ratio. The proposed procedure includes guest exchange in a water-free
bCD matrix. As a result, more stable clathrates with a higher inclusion
capacity can be prepared than by direct saturation of dried or hydrated
bCD. To find an optimal preparation method, the structure–property
relationships were studied for four different ways of bCD clathrate
formation with guests of varying molecular structure. The study was
much simplified by used procedures excluding direct contact of guest
and water liquids with bCD. Besides, in clathrate preparation experiments,
the thermodynamic activities of water and guest were varied independently,
which makes explicit the role of water in this process. Hydration
of bCD reduces its inclusion threshold for hydrophobic guests by their
activity (relative vapor pressure), giving favorable hydration effect
for their inclusion. Besides, water competes with hydrophilic guests
for binding sites in bCD at high water activities. Together with bCD
dehydration by excess of hydrophilic guests, these observations give
a complete thermodynamic picture, which may be fruitful for elaboration
of guest encapsulation techniques by cyclodextrins
Nanostructured Polyelectrolyte Complexes Based on Water-Soluble Thiacalix[4]Arene and Pillar[5]Arene: Self-Assembly in Micelleplexes and Polyplexes at Packaging DNA
Controlling the self-assembly of polyfunctional compounds in interpolyelectrolyte aggregates is an extremely challenging task. The use of macrocyclic compounds offers new opportunities in design of a new generation of mixed nanoparticles. This approach allows creating aggregates with multivalent molecular recognition, improved binding efficiency and selectivity. In this paper, we reported a straightforward approach to the synthesis of interpolyelectrolytes by co-assembling of the thiacalix[4]arene with four negatively charged functional groups on the one side of macrocycle, and pillar[5]arene with 10 ammonium groups located on both sides. Nanostructured polyelectrolyte complexes show effective packaging of high-molecular DNA from calf thymus. The interaction of co-interpolyelectrolytes with the DNA is completely different from the interaction of the pillar[5]arene with the DNA. Two different complexes with DNA, i.e., micelleplex- and polyplex-type, were formed. The DNA in both cases preserved its secondary structure in native B form without distorting helicity. The presented approach provides important advantage for the design of effective biomolecular gene delivery systems