Drug delivery vehicle structure

Up to date, two AIMD studies have been performed in this field. The first dealt with self-assembled polypeptides nanotubes [28]. These systems have a variety of potential application in biochemistry and material science, from optoelectronics to the construction of drug delivery vehicles. Calculations carried out on Cyclo[D-Ala-Glu-D-Ala-Gln]2 in the crystal phase showed also in this case excellent agreement with available structural data and provided novel information on intra- and intermolecular H-bond patterns. 

Thus, the hydrophilic head group and hydrophobic tail of lipids ensure assembly into the oriented bilayer array of cell membranes. The amphiphilic sheet, bilayer, and vesicle are now familiar mofits in biomimetic materials and structures. Synthetic liposomes are employed as biocompatible, biodegradable drug-delivery vehicles. Amphiphile assemblies may serve as templates mono-disperse nanoparticles are synthesized inside reverse micelles, and inorganic structures and materials such as ceramic tubules or mesoporous silica are formed around tubular micelles, rather as inorganics are patterned by vesicles in the formation of the exoskeletons of radiolarians and diatoms. 

One of the several shapes that micelles can take is laminar. Since the ends of such micelles have their lyophobic portions exposed to the surrounding solvent, they can curve upward to form spherical structures called vesicles. Vesicles comprise one or more bUayers surrounding a pocket of liquid, and are formed by molecules such as phospholipids. MultUameUar vesicles have concentric spheres of unilamellar vesicles, each separated from one another by a layer of solvent [105]. Figure 4.10 provides an illustration. Vesicles can be about the same size as living cells, but have a much simpler structure [136-139]. Vesicles can be used as drug delivery vehicles by solubilizing pharmacologically active species in the hydrocarbon core of the bilayers [140,141]. This approach has been used in the treatment of tumors and rheumatic arthritis [142]. 

Figure 12.8 shows the morphological features of cellulose, NC, NC/PVA, and AMO-P(AA-co-AMPS)-g-NC/PVA. Cellulose seems to be fibrous in nature, while, NC looks fluffy and behaves like a gel, which may be due to the increased hydrophi-licity. This gel structure is suitable for the drug delivery vehicles. NC/PVA combines both the nature of NC and PVA. Nanocellulose fibers appear to be dispersed in the PVA matrix. AMO-P(AA-c<9-AMPS)-g-NC/PVA clearly indicates the drug loading and the polymers adhered on the surface of the NC/PVA composite. 

Proteins, as amino acid polymers arranged in a 3D folded structure, are the major structural components of many tissues. They are preferred biomaterials for scaffolds for tissue engineering, and for use as sutures, haemostatic agents and drug delivery vehicles [223]. 

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