Structural Properties of Nonionic Cyclodextrin Colloids in Water

Abstract

The amphiphilic character in water of a novel class of chemically modified cyclodextrins has been investigated by means of small-angle X-ray scattering and light scattering. The introduction ofhydrophilic oligo(ethylene glycol) onto the secondary side of heptakis[6-alkylthio-6-deoxy-2-oligo(ethylene glycol)]-beta-cyclodextrins produces an enhanced water solubility of these molecules. Shape and dimensions of the generated micellar aggregates, analyzed in terms of a suitable core-shell model, remain stable in the wide concentration range explored. The highly associative behavior of these macromolecules is evidenced by the very low value of the critical micelle concentration (cmc), which is about 2 orders of magnitude smaller than the cmc usually obtained for traditional surfactant. Despite the complex geometry of this novel macromolecule, shape and dimensions of generated micellar aggregates can be properly described according to the thermodynamic approaches generally used for amphiphilic molecules and block copolymers. Results show how the modulation of hydrophobic and hydrophilic components sensitively influence the structural features of the generated aggregates thus offering the possibility to control molecular organization in a manner similar to that for traditional colloids. For all the classes of the investigated systems, the small micelles have been found in equilibrium with polydisperse large aggregates of entangled micelles. These novel nonionic colloidal systems combine inclusion and transport properties of host macrocycles, such as cyclodextrin, together with the increased stability of colloidal aggregates, and may be of interest for their potential application as innovative drug delivery systems.

Amphiphilic Cyclodextrins as Nanocarriers of Genistein: A Spectroscopic Investigation Pointing Out the Structural Properties of the Host/Drug Complex System

“…A strategy to improve its rate of absorption and to achieve a rapid onset of activity consists in the encapsulation in nanocarriers of ACyDs. It has been shown that specially designed novel classes of amphiphilic b-CyDs are versatile guest encapsulators due to their capability to form micelles, nanoaggregates, 13,15 or vesicles. [12][13][14]26,34 The main peculiarity emerging from this study is the capacity of Gen to interact with SC6OH forming a stable nanosystem prepared with emulsificationdiffusion method.…”

“…This study was compared with structural properties of analogous systems obtained with conventional method. 15 Furthermore, some preliminary release studies were performed to investigate the potential use of the SC6OH/Gen complex in drug delivery.…”

Structural and dynamic properties of polyoxyethylene sorbitan monooleate micelle in water dispersion studied by pulsed field gradient NMR

“…The restriction size a decreased with increasing POE-SMO concentration from 1.8 gm at 100 mM to 0.8 ~tm at 300 mM, and it was 0.6 gro for surfactant only. The decrease in the restriction size with increasing POE-SMO concentration suggests that the hydrophilic chains at the surface of micelles may play an important role in order to promote the connectivity between micelles by means of the hydrogen bonds [30].…”

Charge interaction of low generation dendrimers during zeolite formation

“…More specifically we evidence that spherical porous nanoparticle were formed when the charged terminal groups of the dendrimer irreversibly anchor the zeolite formation to the dendrimer surface. Such selfassembly recently attracted a sensitive attention in material science [11][12][13][14][15] due also for the important implications in the improvement of the models and theoretical approaches describing the relevant assembly mechanism and processes involved in material and life science [16][17][18][19][20].…”