CD-Containing Polymers

In terms of polymer type, flexibility, size and chemistry, the pendent polymers seem to be excellent candidates for drug delivery vectors. Control of molecular mass and the distribution hydrophobicity, solubility, charge, binding of drug and so on are necessary for use in systemic drug delivery applications. The abihty to time the properties of pendent polymers should facilitate their use in drug delivery applications. As with randomly crosslinked polymers, pendent polymers bind drug molecules via inclusion 

Davis and coworkers created a class of polymers that are linear and have CD as part of the backbone. The key to success in preparing this type of CD-containing polymer is the synthesis of a disfunctionalized CD-containing co-monomer [46]. 

Linear pCD-containing anionic polymers have been used to create conjugates with small-molecule drugs. 

Following is a presentation of the characterization of cyclodextin complexes both in solid and solution state. 

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Figure 10 Components and formulation of targeted nanoparticle-containing siRNA. (a) The delivery components are (1) a water-soluble, linear CD-containing polymer (CDP), (2) an AD-PEG conjugate (PEG of MW 5000 Da) and (3) the targeting component which is an AD conjugate of PEG (PEG of MW 5000 Da) that has human transferrin (Tf) conjugated at the end opposite to the AD (Tf-PEG-AD). (b) The formulation contains two vials, one with SiRNA and the other with the delivery components. When the two vials are mixed together, the targeted nanoparticles form via self-assembly of the four components. From Heidel, J. D. Yu, Z. Liu, J. Y. etal. Proc. Natl. Acad. Sci. U.S.A. 2007, 104,5715. ...

In this chapter we describe conformationally photoresponsive CD-systems of various eomplexity by distinguishing them among functionalized CDs and CD-eontaining small complexes (2.1) supramoleeular nanoaggregates of CD-containing units (2.2) CD-containing polymer-like arrays (2.3) functional surfaces based on CD reeognition (2.4). 

In chromatography, CDs have been used in both stationary and mobile phase methods. In HPLC applications, CDs can be incorporated into stationary phases either by adsorption or bonding onto silica. As an example of the adsorption method, Thuaud et alP first grafted a ff-CD derivative onto a polyvinyl-imidazole (15) that was then absorbed onto silica and used to separate racemic mixtures of amino acid derivatives, among other species, using UV detection. The structure of one )8-CD-containing polymer is shown in Figure 18. 

Nuclear Magnetic Resonance Spectroscopy. Bmker s database, designed for use with its spectrophotometers, contains 20,000 C-nmr and H-nmr, as weU as a combined nmr-ms database (66). Sadder Laboratories markets a PC-based system that can search its coUection of 30,000 C-nmr spectra by substmcture as weU as by peak assignments and by fiiU spectmm (64). Other databases include one by Varian and a CD-ROM system containing polymer spectra produced by Tsukuba University, Japan. CSEARCH, a system developed at the University of Vieima by Robien, searches a database of almost 16,000 C-nmr. Molecular Design Limited (MDL) has adapted the Robien database to be searched in the MACCS and ISIS graphical display and search environment (63). Projects are under way to link the MDL system with the Sadder Hbrary and its unique search capabiHties. 

Excellent electron-transporting properties of quinoxaline (also demonstrated for noncon-jugated quinoxaline-containing polymer 588 [684] and quinoxaline-based polyether 589 [685]) resulted in a substantially decreased turn-on voltage of PPV/590 PLED (3.6 V), which is much lower than that of pure PPV in the same conditions (7 V). These diodes showed a maximum luminance of 710 cd/m2 (ca. 40 times brighter than the PPV diode at the same current density and voltage) [686]. 

Poly(vinyl alcohol) (PVA) seems to be one of the most efficient polymer matrix for CD-containing membranes owing to its ability to form free-standing films and its hydrophilic character due to the presence of hydroxyl groups. In these membrane materials CDs have been either trapped in PVA [83,84] or covalently linked to the chain [106],... 

Premachandran RS, Baneijee S, John VT, McPherson GL, Akkara JA, Kaplan DL (1997) The enzymatic synthesis of thiol-containing polymers to prepare polymer-CdS nanocomposites. Chem Mater 9(6) 1342-1347... 

First of all CD complexation has been used to advantage in classical liquid chromatography and thin layer chromatography.These studies procured very interesting and valuable results which have been recently reviewed (2,1). However, the columns usually containing polymers with incorporated CD molecules are of very low efficiency, owing to the complex mechanism of sorption involving both gel permeation and molecular inclusion. 

Warm water washing of polymer-CD-ICs containing polymer guests insoluble in water or treatment with amylase enzymes serves to remove the host CDs and results in the coalescence of the guest polymers into solid samples. X-ray diffraction, DSC, TGA, and FUR and NMR spectroscopies are typically used to characterize the coalesced polymer samples. 

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