Chemically controlled systems biodegradable

Diffusion-controlled systems, as (a) Reservoir (membrane systems) or (b) Matrix (monolithic systems) (2) Chemically controlled systems that can either be (a) Bioerodible and biodegradable systems or (b) Pendent chain systems ... 

The controlled release of drugs can be realised with many types of active devices, such as mechanical and osmotic pumps, systems of controlled diffusion, chemically-controlled systems composed from bio- or non-biodegradable polymers, magnetically-controlled systems, and not in the last instance chemomechanical systems. Figure 4.39 [136, 137]. 

Finally, chemically inert systems are required in most biomedical applications. Chemical (e.g., hydrolytic) cleavage should be avoided. Exceptions include biodegradable or bioerodible controlled-release systems, which biodegrade by enzymatic or chemical mechanisms at prescribed rates. 

Cloete, T. E., Jacobs, L. and Brozel, V. S., 1998. The chemical control of biofouling in industrial water systems. Biodegradation, 9, 23-21. 

Poly-j3-malate is readily degraded completely to L-malic acid under both acid and base conditions [108], and it can also be hydrolyzed by enzymes within the cell [105,106]. Recently, several bacteria were isolated which were able to utilize poly-/i-malate as sole carbon source for growth [109]. Because the polymer is biodegradable and bioadsorbable, it is of considerable interest for pharmaceutical applications, especially in controlled-release drug delivery systems [97,98]. Chemical routes to poly-/ -malate are expected to provide materials with various properties [110]. 

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