Drug delivery system assemblies

The nanostructured molecular arrangements from DNA developed by Seeman may find applications as biological encapsulation and drug-delivery systems, as artificial multienzymes, or as scaffolds for the self-assembling nanoscale fabrication of technical elements. Moreover, DNA-protein conjugates may be anticipated as versatile building blocks in the fabrication of multifunctional supramolecular devices and also as highly functional-... 

Recently, biodegradable polymers have been used to fabricate macro- and nanometer scale self-assembled systems such as microspheres (MSs), nanospheres (NSs), polymer micelles, nanogels, and polymersomes (Fig. 1). These have attracted growing interest because of their potential utility for drug delivery systems (DDS), tissue engineering, and other applications. To construct these self-assembled systems... 

Other surface-active compounds self-assemble into bilayer structures (schematically illustrated in Fig. 10b), which normally spherilize into structures termed vesicles. When vesicles are formed from phospholipids, the term liposome is used to identify the structures, which also provide useful drug delivery systems [71]. Solutes may be dispersed into the lipid bilayer or into the aqueous interior, to be subsequently delivered through a variety of mechanisms. Liposomes have shown particular promise in their ability to act as modifiers for sustained or controlled release. 

Monolayer blown-film extrusion, VDC copolymers in, 25 725, 728-729 Monolayers, self-assembled, 77 57 Monolayer self-assembled systems, 16 800 Monolignols, 27 10—11, 13, 14 Monolithic drug delivery systems, 9 11 Monomagnesium phosphate, 78 839 Monomer addition, in PVC polymerization, 25 665-666... 

Noncovalent interactions play a special role in synthetic procedures used to assemble various types of supramolecular species. These syntheses rely on the stabilization provided by non-covalent interactions between recognition sites incorporated within precursors. Various types of non-covalent interactions can be used as a recognition motif utilized to guide the synthesis.Targeted synthesis of macro- and supramolecular structures of various sizes, shapes, and functionality has now become possible. Supramolecular chemistry offers incredible applications in various fields such as medicinal chemistry (drug delivery systems),host-guest chemistry,catalysis,and molecular electronics. ... 

A composition based on diketopiperazine derivatives (3,6-bis (N-fumaryl-N-(n-butyl) amino-2, 5-diketopiperazine) has been investigated as a pulmonary drug delivery system, termed Technospheres (Pharmaceutical Discovery Corp., Elmsford, NY) (Pohl et al. 2000 Steiner et al. 2002). The diketopiperazine derivatives self-assemble into microparticles at low pH with a mean diameter of approximately 2 pm. During self-assembly, diketopiperazine derivatives microencapsulate peptides present in the solution. Insulin incorporated in diketopiperazine derivatives (TI) was administered to five healthy humans by the use of a capsule-based inhaler with a passive powder deagglomeration mechanism. Relative and absolute bioavailability of TI in the first 3 hours (0-180 min) were 26 12% and 15 5%, and for 6 hours (0-360 min) 16 8% and 16 6%, respectively (Steiner et al. 2002). The time to peak action for glucose infusion rates was shorter with both IV (14 6 min) injection and inhalation (39 36 min), as compared to SC administration (163 25 min). This rapid absorption of insulin would be beneficial for diabetic patients who need to rapidly affect their glucose levels. 

Na K, Lee ES, Bae YH (2003) Self-assembled nanoparticles of hydrophobically-modified polysaccharide bearing vitamin H as a targeted anti-cancer drug delivery system. Eur J Pharm Biopharm 18(2) 165-173... 

Boden, N., Aggeli, A., Ingham, E., and Kirkham, J. Supramolecular Networks Made by Beta-Sheet Self-Assembly of Rationally Designed Peptides, and Their Uses as Industrial Fluids, Personal Care Products, Tissue Engineering Scaffolds and Drug Delivery Systems, 2003-GB3016 WO 2004007532 (2004). 

The spherical self-assembly in aqueous solution originates from the mushroom shape of the molecule. Moreover, when hydrophobic molecules are present, the micelle includes them as guest molecules, acting as a molecular capsule. As selective adsorption of Pcs to cancer cells has been used as a tool for PDT, these micelles hold potential as drug delivery systems. 

This section focuses on adhesives that are used for the assembly of medical devices. In medical device assembly, the primary substrates are plastics, elastomers, and metals. The total medical adhesive market is much larger since it encompasses a broader definition of products. For example, medical adhesives can be used for bonding human tissue, transdermal drug delivery systems, dental restoration, and wound care in addition to medical device assembly. 

It has to be clear that, once diluted and injected (or administered in ocular and other routes), the emulsion stability and fate are determined by three measurable parameters. The first is the partition coefficient of each emulsion component (including added drugs and agents) between the emulsion assembly and the medium. To some extent this partition coefficient is related to oil-water and/or octanol-water partition coefficients. For example, it was well demonstrated that per component of which logP is lower than 8, the stability upon intravenous (IV) injection is questionable [42,138], The other two parameters are kQff, a kinetic parameter which describes the desorption rate of an emulsion component from the assembly, and kc, the rate of clearance of the emulsion from the site of administration. This approach is useful to decide if and what application a drug delivery system will have a chance to perform well [89],... 

HaloLite, shown in Fig. 11, is a hand-held drug delivery system developed by Medic-Aid (Bognor Regis, United Kingdom). The device, which uses compressed air, consists of a medication chamber, a control unit, and an aerosol generation assembly that is operated by a portable, dedicated compressor. The aerosol is generated based upon conventional nebulization principles. The control unit allows the patient to select a... 

Fig. 3 Exploded view of an iontophoretic drug delivery system showing major components top housing, printed circuit board assembly, a bottom housing containing reservoirs for placement of electrodes and hydrogels, and an adhesive laminate. (Diagram from International Patent Publication Number WO 96/39222.)...

Physical hydrogels were formed induced by self-assembled water-insoluble and crystalline polypseudorotaxane domains which act as physical crosslinking points. Such physical hydrogels include the polypseudorotaxane systems of a-CD threading on PEO or its copolymers, a-CD threaded on PEI, PL, or their copolymers, and even 3-CD or y-CD threaded PPO or PEI copolymers. The thermo-reversible and thixotropic properties of these supramolecular hydrogels have inspired their applications as injectable drug delivery systems. Physical hydrogels induced by physical interaction of threaded CD molecules in polyrotaxanes were also developed. 

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