Polymeric drug delivery systems biodegradable polymers

To enhance the desirable properties of a polymer as a matrix for a controlled drug delivery system, efforts have been made to improve its hydrophilicity, biodegradation rate, and drug stability. Hydrophilic blocks play vital role in polymeric drug delivery systems, for example, poly(ethylene oxide)... 

Based on the properties of the polymeric material, polymeric drug delivery systems (DDS) can be classified as non-degradable DDS or biodegradable DDS. Table 16.2 lists some of the most commonly used polymers in the preparation of DDS. This list includes synthetic, natural and modified natural polymers. Although natural polymers and their derivatives, as for example chitosan and gelatin [4,18], are also used in the development of ODDS, this work will be focused solely on synthetic polymers and on the ODDS based on these polymers. 

Figure 10.3 Structures of polymers and polymeric drug delivery systems sensitive to temperature, near-infrared light, and magnetic fields, (a) Temperature-sensitive biodegradable block copolymer (Kim et al., 2011). (b) NIR-sensitive PLGA microspheres contaming hoUow gold nanoparticles (You et al., 2010). (c) NIR-sensitive hybrid nanogels (Wu et al., 2010).

Polymers containing labile groups present an advantageous opportunity to develop redox-responsive biodegradable systems. Disulfide linkages have been broadly applied in reduction-responsive polymeric drug delivery systems [117]. In fact. 

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],... 

Chasin, M. andLanger,R. (eds) (1990) Biodegradable Polymers as Drug Delivery Systems. Marcel Dekker, New York. Tsirita, T., Hayashi, T., Ishihara, K., Kataoka, K. and Kimura, Y. (eds) (1993) Biomedical Applications of Polymeric Materials. CRC Press, Boca Raton, Florida. 

Numerous microfabrication techniques have been used to produce a wide range of implantable and oral drug delivery systems using materials ranging from silicon, glass, silicone elastomer, and plastics. Fabrication techniques have rapidly evolved to produce nanoscale objects and therapeutic systems using polymeric materials as the substrate due to their biodegradable nature. There are a number of different synthetic polymer systems that have been developed for this type of application, and the most common ones are listed below ... 

Poly (e-caprolactone), poly lactides, and polyglycolides have quite unusual properties of biodegradability and biocompatibility. The majority of polymers used in the biomedical field to develop implants, sutures, and controlled drug-delivery systems are the aforesaid resorbable polyesters produced by ring-opening polymerization of cyclic (di)esters. 

The doublet structure of the methyl signal at 17 ppm is caused by the stereochemistry. Polylactides, not yet described in any pharmacopoeias, are rather new biodegradable polyesters derived from the chiral lactic acid and used, e. g., in drug delivery systems. The stereochemistry of the polymer is important to the physical and chemical behavior, especially the polymer properties. Pure tactic polymerization can be differentiated from atactic or mixed polymers by simple comparison of the C NMR spectra (Figure 3-10) [4]. 

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