Cyclodextrin-containing Systems

In an attempt to increase the number of useful components for construction of new catenanes, the Stoddart group recognised that cyclic sugars of the cyclodextrin type were promising candidates.  

Since they anticipated difficulties in the isolation of unmodified catenated cyclodextrins, the Stoddart group initiated their studies using the poly-methylat-ed derivative 45 of the seven-membered sugar unit, P-cyclodextrin. The latter has 

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Lin et al. [95] used capillary electrophoresis with dual cyclodextrin systems for the enantiomer separation of miconazole. A cyclodextrin-modified micellar capillary electrophoretic method was developed using mixture of /i-cyclodextrins and mono-3-0-phenylcarbamoyl-/j-cyclodextrin as chiral additives for the chiral separation of miconazole with the dual cyclodextrins systems. The enantiomers were resolved using a running buffer of 50 mmol/L borate pH 9.5 containing 15 mmol/L jS-cyclodextrin and 15 mmol/L mono-3-<9-phcnylcarbamoyl-/j-cyclodextrin containing 50 mmol/L sodium dodecyl sulfate and 1 mol/L urea. A study of the respective influence of the /i-cyclodcxtrin and the mono-3-(9-phenylcarbamoyl-/i-cyclodextrin concentration was performed to determine the optical conditions with respect to the resolution. Good repeatability of the method was obtained. 

Since these studies, many other rotaxanes incorporating cyclodextrins or their substituted derivatives have been reported, including other metal-containing systems. The latter include a series of a-cyclodextrin rotaxanes formed by the reaction of labile [Fe(CN)50H2J ions with pre-threaded l,l"-(a,(o-alkanediyl)-bis(4,4 -bipyridinium) dicationic moieties (incorporating methylene chains between 8- and 12-members long). " ... 

The crucial challenge of in vivo application of RNAi therapy is developing efficient delivery system to transport the siRNA into the tissue and finally into the cytoplasm or shRNA into the nucleus of target cells [4]. Several studies have demonstrated efficient delivery of siRNA in vivo as well as its therapeutic effect in animal model. Recently in 2008, FDA approved the first clinical study using targeted cyclodextrin-containing nanoparticle for the systemic delivery of an anti-cancer siRNA, RONDEL , developed by Calando Pharmaceutical Inc. 

Fig. 7 Schematic diagram of the cyclodextrin-containing delivery system, (a) Components of the delivery system. The CDP condenses siRNA and protects it from degradation. The AD-PEG stabilizes the complexes in systemic circulation via inclusion compound formation. The AD-PEG-transferrin (Tf-PEG-AD) conjugate confers a targeting ligand to the complex, (b) Assembly of the targeted delivery systems. CDP, AD-PEG, and Tf-PEG-AD are combined and added to siRNA to generate stable complex. (Adopted from Cancer Research 2005 65 8984-8992)...

B. Cappello, G. De Rosa, L. Giannini, M.-I. La Rotondci, G. Mensitieri, A. Mtro, E Qucigha and R. Russo, Cyclodextrin-containing poly(ethyleneoxide) tablets for the delivery of poorly soluble drugs Potential as buccal delivery system, Int. J. Pharm., 319 (1-2) 63-70, 2006. 

Ekgorg-Ott et al. (1997). An interesting trend was discovered when considering the relative amount of D-theanine present in the samples. The teas of the highest grades consistently contained the lowest amounts of D-theanine. The theanine achiral-chiral system configuration included a C18 column operated in the reverse-phase mode and a y-cyclodextrin CSP in the polar organic mode. 

Metalated container molecules can be viewed as a class of compounds that have one or more active metal coordination sites anchored within or next to a molecular cavity (Fig. 2). A range of host systems is capable of forming such structures. The majority of these compounds represent macrocyclic molecules and steri-cally demanding tripod ligands, as for instance calixarenes (42), cyclodextrins (43,44), and trispyrazolylborates (45-48), respectively. In the following, selected types of metalated container molecules and their properties are briefly discussed and where appropriate the foundation papers from relevant earlier work are included. Porphyrin-based hosts and coordination cages with encapsulated metal complexes have been reviewed previously (49-53) and, therefore, only the most recent examples will be described. Thereafter, our work in this field is reported. 

In this study, methylated -cyclodextrins were found to accelerate the polymerization of aryl group-containing water-insoluble monomers using water-soluble initiators in a two phase water/chloroform system. The results are consistent with transport of monomer from the organic phase to the aqueous phase, where initiation of the polymerization begins, followed by... 

The stability of the polypyridyl rhenium(I) compounds mentioned above stimulated applications of this coordination chemistry. Thus, new heterotopic bis(calix[4]arene)rhenium(I) bipyridyl receptor molecules have been prepared and shown to bind a variety of anions at the upper rim and alkali metal cations at the lower rim. A cyclodextrin dimer, which was obtained by connecting two permethylated /3-cyclodextrins with a bipy ligand, was used for the preparation of a luminescent rhenium(I) complex. The system is discussed as a model conipound to study the energy transfer between active metal centers and a bound ditopic substrate. The fluorescence behavior of rhenium(I) complexes containing functionalized bipy ligands has been applied for the recognition of glucose. ... 

An interesting example of a system whose components become mechanically bound upon surface immobilization is rotaxane trans-21 (Fig. 13.24), consisting of a ferrocene-functionalized /3-cyclodextrin (fi-CD) macrocycle threaded on a molecule containing a photoisomerizable azobenzene unity and a long alkyl chain.33 A monolayer of trans-21 was self-assembled on a gold electrode. Therefore, the ring... 

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