Polymers polymeric materials biodegradability

Over the past two decades, the trend of using biodegradable materials instead of biostable materials has rapidly emerged in the case of various applications [44]. Because of the diverse features of polymeric materials, biodegradable polymers are rapidly replacing other materials such as metals, alloys, and ceramics [45]. This tremendous increase in the use of biodegradable materials supports the prediction that many of the permanent prosthetic devices used currently will be replaced by biodegradable devices in... 

Zhu, K. J., Xiangzhou, L., and Shilin, Y., Preparation and properties of D,L-lactide and ethylene oxide copolymer A modifying biodegradable polymeric material, J. Polym. Sei. Part C Polvm. Lett.. 24, 331-337, 1986. 

Carbon dioxide is a widely available, inexpensive, and renewable resource. Hence, its utilization as a source of chemical carbon or as a solvent in chemical synthesis can lead to less of an impact on the environment than alternative processes. The preparation of aliphatic polycarbonates via the coupling of epoxides or oxetanes with CO2 illustrates processes where carbon dioxide can serve in both capacities, i.e., as a monomer and as a solvent. The reactions represented in (1) and (2) are two of the most well-studied instances of using carbon dioxide in chemical synthesis of polymeric materials, and represent environmentally benign routes to these biodegradable polymers. We and others have comprehensively reviewed this important area of chemistry fairly recently. Nevertheless, because of the intense interest and activity in this discipline, regular updates are warranted. 

This book is a companion volume to Pharmaceutical Technology Controlled Drug Release, Volume 1, edited by M.H.Rubinstein and published in 1987. It focused on the different types of polymeric materials used in controlled release. This book extends these concepts to include drug properties, design and optimization, coating, the effect of food and pharmacokinetics. It also reflects the growing interest in biodegradable polymers in oral and topical formulations and the use of sterile implants. 

The response reaction of the host to a foreign material remaining in the body for an extended period of time is a concern. Thus, any polymeric material to be integrated into such a delicate system as the human body must be biocompatible. Biocompatibility is defined as the ability of a material to perform with an appropriate host response in a specific application [79]. The concept include all aspects of the interfacial reaction between a material and body tissues initial events at the interface, material changes over time, and the fate of its degradation products. To be considered bio compatible, a biodegradable polymer must meet a number of requirements, given in Table 2. 

Polymeric nanoparticles have attracted a lot of attention in the last years. Polymeric materials exhibit several advantageous properties including biodegradability and ease of functionalization. They also allow for a greater control of pharmacokinetic behavior of the loaded drug leading to more steady levels of drugs (Rawat et al. 2006). Furthermore, they enable the modulation of the physicochemical properties of the surface such as Zeta potential and hydro-phobicity/hydrophilicity. Many polymers used to develop nano- and... 

Since the dissolution of polymeric materials is the key to this mechanism, the polymers used must be water-soluble and/or degradable in water. The choice of a particular polymer for a particular controlled release dosage form depends on various factors such as the dissolution mechanism, delivery period, delivery route, the drag etc. In general, synthetic water-soluble polymers tend to be widely used for oral-controlled release dosage forms. Biodegradable polymers tend to be used for injectable, or implantable, drag delivery systems. 

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. 

Wood and, polymers. Natural materials as well as materials manufactured from plant or animal origin, such as wood, cotton, paper products, wool, and leather, etc., are fully biodegradable under aerobic conditions. (Dexter)5 Plastics are materials that consist mainly of highly polymeric, organic compounds. Also, nondegradable polymer may become degradable by a combined chemical, physical, and biological attack.64,67... 

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 ... 

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