Biodegradable matrices

Incorporation of the tetrahydrofuran ring into condensation polymers has been accomplished (79USP4180646) by transesterification of orthoester (43) with polyols to prepare poly (orthoesters) (44 Scheme 11). This polymerization reaction has been extended to a wide variety of other orthoester and orthocarbonate starting materials. The product polymers are reported to be excellent biodegradable matrices for drug delivery. 

In addition to these, however, a number of interesting 1,3-dioxane-containing polymers have been obtained (B-77MI11105) from spiroacetals (150) derived from pentaeryth-ritol and functionalized aldehydes (Scheme 47). These and other related spiro-1,3-dioxane polymers have attracted interest as fiber- and film-formers and as biodegradable matrices for drug delivery systems. 

Parenteral depot or placement (e.g., coronary) Various subungual, surgical fields, vessels Sustained-release injectable biodegradable matrices or splints... 

Biodegradable matrices for controlled release and cell encapsulation... 

Products with readily variable dose levels are required. Methods for depositing drugs in solution onto biosoluble and biodegradable matrices also offer the possibility of ready and accurate fabrication in hospital and community pharmacies. A matrix platform for such products is required. Developments in bubble jet devices (22) suggest the possibility of the deposition and the adsorption of the smallest doses onto and into suitable matrices for delivery, say, to neonates by oral or buccal routes. 

Harris L D, Kim B S, Mooney D J (1998). Open pore biodegradable matrices formed with gas foaming. /. Biomed. Mater. Res. 42 396-402. 

The stereocomplex formation of PLLA and PDLA is enhanced in the presence of stereoblock poly(lactic acid) [419], Stereocomplex formation was proposed to be a novel method of controlling the protein- and cell-adhesive properties of biodegradable matrices composed of PEG-PLA copolymers [420], A triangular growth mechanism was proposed for the PLLA/PDLA stereocomplex [95], and the nucleating mechanism is not altered by the PLLA/PDLA blending ratio [421],... 

L. Harris, D.J. Mooney, and L. Shea, Open pore biodegradable matrices, US Patent 6 281256, assigned to The Regents of the University of Michigan (Ann Arbor, MI), August 28, 2001. 

Being 100% cellulose, rayon is completely bio-based and biodegradable. Thus, it is an obvious choice for bio-based and/or biodegradable matrices such as PLA or PHA. Compared to natural fibers, the compact structure and the well-defined and constant properties as well as the availability on an industrial scale and ease of handling are advantageous. 

Nano-biocomposites use biodegradable matrices and incorporate nanofillers to minimize the disadvantages of not using traditional packaging materials. These materials, besides protecting food from its surroundings and prolonging its shelf-life, are more environmentally friendly. ... 

The most widely used reinforcements in nanocomposites are carbon nanotubes, layered clay, and nanoparticles. The most widely used polymer matrices are polyamides, nonpolar polymers, polyesters, epoxies, and polyurethane. However, this chapter will focus on nanocomposites which are made from both biodegradable fiber/fillers and biodegradable matrices, since only these composites truly justify the definition of eco-friendly and green nanocomposites. 

Research activity seeks to improve cyclosporine absorption for enhanced bioavailability target its delivery to treatment areas to result in a therapeutic response, while blunting systemic adverse effects prolong the drug s release over time for sustained therapeutic concentrations. A most notable undesirable CsA effect is its deleterious nephrotoxicity via afferent arteriole vasoconstriction in the glomerulus. Delivery systems prominently under investigation are polymeric micelles, nanoparticles, and biodegradable matrices.These are examined and discussed in further detail below. 

This chapter reviews the potential use of proteins, polysaccharides, lipids and biopolyesters as biodegradable matrices for coating, encapsulation and packaging applications. 

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