Biomimetic Cooperative Interactions of Dried Cross-Linked Poly(N-6-aminohexylacrylamide) with Binary Mixtures of Solvent Vapors

Guest inclusion by native cyclodextrins in solid state and solutions: A review

In many industrial applications, preparation of cyclodextrin (CD) inclusion complexes with drugs, food additives, dyes and components of essence oils is performed in solid mixtures, slurries or paste-like systems having lack of water to dissolve cyclodextrin and guest completely. Such systems need a different description than supplied by classical analysis of CD complexation in aqueous solutions. The main feature of solid-state guest inclusion is the phase transition from solid CD to solid inclusion compound. This implies a complex interplay between a size exclusion effect for guest inclusion, a cooperative activation of this process by the third component such as water or organic compound and competition of guest and water for the space inside CD crystal lattice. The present review summarizes the current state of research of guest inclusion by native CDs in solid state and compares the driving forces of this process and its structure-property relationships with those of complexation in aqueous solutions. For an adequate comparison, the latter process was analyzed in thermodynamic activity scale, which allowed to separate hydrophobic effect and such important factors of complex stability as guest molecular shape and "high-energy" water.

Smart Molecular Recognition: From Key-to-Lock Principle to Memory-Based Selectivity

The formation and decomposition of inclusion compounds with a solid-solid phase transition may be very selective to the guest molecular structure. This selectivity may function in essentially different ways than defined by the classical concept of molecular recognition, which implies the preferential binding of complementary molecules. Solid inclusion compounds may take part as an initial or/and final state in several processes of different types summarized in this review, which selectivity is boosted by cooperativity of participating molecular crystals. Some of these processes resemble switching electronic devices and can be called smart giving practically absolute molecular recognition.

Smart control of guest inclusion by α-cyclodextrin using its hydration history

Hydration history was found to control the inclusion capacity of α-cyclodextrin (aCD) for volatile organic guests, so that its level may be switched from zero to the stoichiometric value and back by the variation of aCD hydration/dehydration order and direction. Such variation of the inclusion capacity is caused by the balance of two water roles: the activation of guest inclusion and guest/water competition. These observed concurrent roles and the cooperativity of guest inclusion and hydration make possible the smart tuning of the guest inclusion by the subtle change of preparation procedure. Depending on the hydration history, aCD was shown to form hydrates with the same water contents but different packing types and different kinetics of dehydration, which correlates with their different inclusion capacities for organic guests. This correlation reveals how the “high-energy” and “low-energy” water works in the guest inclusion by aCD, which may be relevant for other cyclodextrins and hydrophilic receptors of biomimetic and biological natures. The results can help to rationalize the technologies of producing various inclusion compounds of cyclodextrins.

The hydration level and hydration history of alpha-cyclodextrin significantly affects its structure and inclusion capacity for organic guests.

Using water-mimic organic compounds to activate guest inclusion by initially dry beta-cyclodextrin

Optimal conditions were found enabling anhydrous beta-cyclodextrin (bCD) to include target guests using small monofunctional organic compounds instead of water.

Interaction of l-alanyl-l-valine and l-valyl-l-alanine with organic vapors: thermal stability of clathrates, sorption capacity and the change in the morphology of dipeptide films

The change of the surface morphology of thin film of dipeptides correlates with stoichiometry of their clathrates.

Molecular imprinting science and technology: a survey of the literature for the years 2004-2011

Herein, we present a survey of the literature covering the development of molecular imprinting science and technology over the years 2004-2011. In total, 3779 references to the original papers, reviews, edited volumes and monographs from this period are included, along with recently identified uncited materials from prior to 2004, which were omitted in the first instalment of this series covering the years 1930-2003. In the presentation of the assembled references, a section presenting reviews and monographs covering the area is followed by sections describing fundamental aspects of molecular imprinting including the development of novel polymer formats. Thereafter, literature describing efforts to apply these polymeric materials to a range of application areas is presented. Current trends and areas of rapid development are discussed.

Effect of H2O−CO2 Organization on Ovalbumin Adsorption at the Supercritical CO2−Water Interface

We have studied the formation of water-CO(2) interfaces in the presence of different concentrations of ovalbumin (OVA) by tensiometry and by means of interfacial rheological measurements to obtain some information on the capacity of protein film to stabilize H(2)O in CO(2) emulsion. The formation of pure water-CO(2) interface can be described as a two-step phenomenon.(1) The CO(2) molecules adsorb onto the water surface and then a reorganization of the interface creates a H(2)O-CO(2) cluster network. This organization occurs at a temperature (40 degrees C) higher than the higher temperature limit (10 degrees C) allowing the formation of crystalline structure called CO(2) clathrate.(2) Our results show that ovalbumin adsorption from bulk concentrations higher than 0.0229 g/L inhibits the cluster formation for a CO(2) pressure less than 80 bar. However, for lower concentrations, the more the CO(2) pressure is close to 80 bar, the more OVA adsorption is reduced by the H(2)O-CO(2) cluster network. Moreover, from a pressure of 90 bar, the affinity of OVA for the interface increases and mixed films made of protein molecules and clusters are obtained for the OVA concentrations lower than 1 g/L.