Biodegradable material degradation

This device is configured so that upon exposure to an acidic environment, an amount of the second biodegradable material degrades and releases the encapsulated buffering agent in an amount that provides a stoichiometric balance between the amount of buffering agent released and the total amount of acid released from the device, such that the pH level is raised to a neutral pH level (60). 

The second reason is that these materials release degraded substances that may cause toxic effects in the body. The toxicity caused by biomaterials is mostly due to the low molecular weight compounds that leach from the biomaterials into the body of the patient, which include unpolymerized monomers, additives, and fragments of polymerization initiators, and catalysts [4]. Currently, these compounds are controlled under regulation limits. For biodegradable materials, degraded substances are constantly released in the body. The safety of their subsequent metabolites must be carefully considered. 

The concept of using biodegradable materials for implants which serve a temporary function is a relatively new one. This concept has gained acceptance as it has been realized that an implanted material does not have to be inert, but can be degraded and/or metabolized in vivo once its function has been accompHshed (12). Resorbable polymers have been utilized successfully in the manufacture of sutures, small bone fixation devices (13), and dmg dehvery systems (qv) (14). 

These environmental issues, created a dire need for the development of green polymeric materials, which would not involve the use of toxic and noxious component in their manufacture and could be degradable in nature. For these reasons, through the world today, the development of biodegradable materials with controlled properties has been a subject of great research challenge for the community of material scientists and engineers. 

There are 22 chapters in the book and they cover the most important aspects of polymers as drugs, prodrugs, dmg delivery systems, and in situ prostheses. The major features promulgated are synthesis, derivatization, degradation, characterization, application, and evaluation techniques as well as new biodegradable materials, assemblies, hydrogels, telechelic polymers, derivatized polysaccharides, micro- and nanoparticles, mimetic... 

PVA films buried in soil were tested after 120 days and showed only very limited signs of biodegradation, and even field tests with PVA sheets buried for 2 years in different natural soil sites showed only limited (10%) weight loss. No traces of colonising microorganisms were detected on the incubated material. Degradable polymers like poly(hydroxy butyrate), PCL or starch are usually extensively... 

Composts can be made from most biodegradable materials, and could derive from many unusual sources. If it originates from municipal solid waste, however, care should be taken that no toxic and non-degradable materials remain after the supplier s separation processes. Small pieces of brick and concrete, glass and plastic (inerts), lead residues from old car batteries and cadmium from electroplated items are possible. A useful work on specifications and recommended chemical analyses of composts is the book by Bertoldi et al., 1987. 

A managed process that controls the biological decomposition of biodegradable materials into a humus-like substance called compost The aerobic and mesophilic and thermophilic degradation of organic matter to make compost the transformation of biologically decomposable materials through a controlled process of bio-oxidation... 

Biological processes for pollutant treatment are frequently the method of choice (see Chapter 11). However, the complexity of some wastes (e.g., refractory and/or highly toxic) necessitates other approaches such as the use of hybrid alternatives that offer the possibility for partial electrochemical degradation (e.g., the transformation of non-biodegradable material into biodegradable). This involves large savings in electricity, because—as shown in Example 10.3—in order to completely oxidize... 

Chitin is a biodegradable material and undergoes biodegradation by enzymes such as lysozyme and chitinase. In vivo studies showed that lysozyme plays an important role in the degradation of chitin to produce... 

Hydroxyapatite and magnesium oxide improve biodegradation of polylactides. The degradation occurs in the bulk material whereas, in unfilled material, degradation occurs by surface erosion. 

---