Lipophilic core

Some of their derivatives have been used as antiviral drugs. Due to their flexible chemistry, they can be exploited to design drug delivery systems and in molecular nanotechnology. In such systems, they can act as a central lipophilic core and different parts like targeting segments, linkers, spacers, or therapeutic agents can be attached to the said central nucleus. Their central core can be functionalized by peptidic and nucleic acid sequences and also by numerous important biomolecules. 

However, these elegant glycosylated nanostructures displayed only weak biological activity relative to their native glucan elicitor counterparts. Nevertheless, such glycoclusters provided unique environments for host-guest chemistry of amphi-pathic molecules owing to their lipophilic core surrounded by a hydrophilic periphery. 

Incorporation of an alkyne moiety within the lipophilic core (e.g., 23) imparts helical and scissors-like morphology to the stacked array (e.g., 24 and 25, respectively). Disclike, benzene-based arborols have also been reported1891 to form //-bonded aggregates, or networks, comprised of approximately 50-60 dendrimers. The approximation is based on network diameters determined from electron microscopy. 

In order to exploit the lipophilic core of the cylindrical aggregate, V,A, V",A "-tetrakis[2-hydroxy-1,1 -bis(hydroxymethyl)ethyl]hexadec-8-yne-l,l,16,16-tetracarboxamide was prepared this unsaturated ar-borol, possesses a centrally located alkyne moiety, and upon dissolution in water forms a gel comprised of a similar stacking motif to the saturated counterpart. The electron micrograph of this gel showed a unique aggregation pattern, in which bundles of intertwined aggregate columns were formed. The resultant, inherently helical pattern is in stark contrast to the needle-like structures formed by the related [9]-10-[9]-arborol. 

PEG)-modified phospholipids provides a hydrophilic shell that surrounds the lipophilic core and creates a steric barrier. PEG derivatives were shown to prevent serum protein binding, to reduce phagocytotic cell-mediated recognition, and to result in increased circulation lifetimes (18). Polyglycerolated phospholipids are said to inhere a similar potential of reducing opsonization processes while showing reduced toxicity (19). 

Figure 12.1 Schematic model of a rod-like micelle. L is the cylindrical length of the rod-like lipophilic core, r is the average lipophilic length, a, and a 2 are the...

For the hexagonal phase, the radius of the rod-like aggregate lipophilic core (rj and the effective cross-sectional area per lipophilic chain (Oj) are calculated by Equations 12.5 and 12.6 [35, 36] ... 

Some drug absorption enhancers are capable of loosening tight junctions (zonula occludens) and thereby facilitate paracellular absorption of drug molecules and improve the bioavailability of active pharmaceutical ingredients with low membrane permeability. The penetration enhancers include chelating agents [e.g., ethylenediaminetetraacetic acid), toxins [e.g., zonula occludens toxin), plant-derived materials [e.g., aloe vera gel), and cationic polymers. Polycationic lipophilic-core dendrons, which form lipophilic ion-pairs with heparin, were studied as a system for oral delivery of heparin. ... 

Further, the ability to synthesize random copolymers with various hydrocarbon monomers allows the anchor-soluble balance to be tuned while maintaining solubility even with high incorporations of hydrocarbon comonomers [29]. Because of the amphiphilic nature of such copolymers, it was predicted that these materials would selfassemble into micelles consisting of a highly fluorinated corona segregating the lipophilic core from the compressed CO2 continuous phase. Thus, PFOA-F-PS block copolymers were synthesized via controlled free-radical techniques (Fig. 9.3), and it was confirmed (by smaU-angle neutron scattering) that these copolymers spontaneously assemble into multimolecular micelles in solution [40]. In addition to amphiphilic materials, which physically adsorb to the surface of polymer particles in dispersion polymerizations, fluorinated acrylates can be utihzed as polymerizable comonomers in the stabilization of C02-phobic polymer colloids [41]. 

Hopanoids are membrane stabilizers in certain procaryotes (E 2.2). Their hydrophilic, polyhydroxylated side-chain is directed towards the aqueous face the lipophilic ring system is integrated in the lipophilic core of the membranes. Lanosterol is used as emulsifier in the pharmaceutical industry. Cucurbitacins due to their bitter taste may discourage animal predators, but attract certain beetles, which use Cucurbitaceae as food plants (E 5.5.3). 

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