Biodegradable polymer examples

More recently chitosan polymers which are derivatives of chitin materials have evoked interest due to their bioactivity and biodegradability. For example, N-carboxybutyl chitosan has been show to effectively promote wound healing (9). Acetate, and butyrate derivatives of chitosan have decreased blood clotting time significantly (10). 

Table HI. Examples of Biodegradable Polymers Used in Drug Delivery...

Biodegradable polymers can be categorized into natural and synthetic polymers. The typical examples of natural biodegradable polymers are proteins,... 

The choice of biodegradable polymers coming from synthesis or bacterial fermentation is wide. For example ... 

Synthesis of aminopolysaccharides, therefore, is one of the important research areas in the field of functional materials, examples of biorelated polymers, antibacterial substance, and biodegradable polymers as well as materials for drugs and matrices of drug delivery systems. Only a few methods, however, such as ring-opening polymerization and enzymatic polymerization have been available for the precision synthesis of aminopolysaccharides [4,5],... 

What Is a biodegradable polymer Give an example of a biodegradable aliphatic polyester. 

Incorporation of F-chain end-groups into biodegradable polymers can help modulate their biodegradation (e.g., the hydrolysis rate of polyesters) and drug release [68], Surface treatment of polymer for example, poly(lactic-co-glycolic acid)... 

ITABLE 13.5. Examples of biodegradable polymers tested for sustained protein release... 

Biodegradable polymers, both synthetic and natural, have gained more attention as carriers because of their biocompatibility and biodegradability and therewith the low impact on the environment. Examples of biodegradable polymers are synthetic polymers, such as polyesters, poly(orfho-esters), polyanhydrides and polyphosphazenes, and natural polymers, like polysaccharides such as chitosan, hyaluronic acid and alginates. 

Few works on proteins encapsulation have been presented. A recent study by Young et al. [60] deals with the encapsulation of lysozyme in biodegradable polymer microspheres. A 1-10 pm lysozyme particle suspension in a polymer solution was sprayed into a CO2 vapour phase through a capillary nozzle. The droplets solidified after falling into the liquid phase. By delaying the precipitation in the vapour phase, the larger microparticles obtained were able to encapsulate the suspended lysozyme. The final capsules were in the range of 5 - 70 pm. This work is a nice example of protein encapsulation for microparticle delivery systems. 

Fig. 3 Hydrolyzable, acid-sensitive and reducible bonds. Efficient and biocompatible high molecular weight polymers are created by reversible linkage of small molecular weight compounds. Thus, programmed biodegradation due to, for example, hydrolyzable ester bonds [92] (a), acid-sensitive ketal (b) or acetal linkages (c) [98] is possible. The reducing cytosolic environment can also be taken advantage of in order to create biodegradable polymers by introduction of disulfide bonds as shown in (d) [105, 106]...

Polyphosphazenes are a relatively new class of biodegradable polymers. Their hydrolytic stability or instability is determined not by changes in the backbone structure but by changes in the side groups attached to an unconventional macromolecular backbone. Synthetic flexibility and versatile adaptability of polyphosphazenes make them unique for drug delivery applications. For example, Veronese et al.18 prepared polyphos-phazene microspheres with phenylalanine ethyl ester as a phosphorous substituent and loaded it with succinylsulphathiazole or naproxen. The kinetics of release from these matrices were very convenient in yielding local concentrations of the two drugs that are useful per se or when mixed with hydroxyapatite for better bone formation. Polyphosphazene matrices are also considered as potential vehicles for the delivery of proteins and vaccines.19... 

Finally, it may be noted that 4,6-orthoesters obtained for example by reaction of sucrose with ethyl orthoacrylate can be opened to form either the 6- or 4-esters,146 providing convenient starting materials for the preparation of biodegradable polymers (see Scheme 7). 

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