Polymeric materials Biodegradable water-soluble

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. 

Natural organic matter from biosynthesis and biodegradation is ubiquitous in natural aqueous environments. Common examples of natural organic materials are extracellular polymeric matrices (biofilms) generated by bacteria, hydrocarbons from industrial effluents and fossil fuel products, and numerous humic substances. Because of their hydrophobicity, natural organic materials have low solubility in water and tend to accumulate at solid surfaces. As a result, in groundwater and soils, mineral surfaces are commonly coated with organic films. 

Biodegradation normally refers to an attack by microorganisms on water insoluble polymers. This implies that the biodegradation of plastics is usually a heterogeneous process. Due to the lack of water solubility and the size of the polymer molecules, miaoorganisms are unable to transport the polymeric material directly into the cells where most bioehemical processes take place rather, they must first excrete extracellular enzymes, which de-polymerize the polymers outside the cells. As a consequence, if the molar mass of the polymers can be sufficiently reduced to generate water-soluble intermediates, they can be transported into the miaoorganisms and fed into the... 

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