Biopolymers natural origin

Polymers are substances whose molecules are very large, formed by the combination of many small and simpler molecules usually referred to as monomers. The chemical reaction by which single and relatively small monomers react with each other to form polymers is known as polymerization (Young and Lovell 1991). Polymers may be of natural origin or, since the twentieth century, synthesized by humans. Natural polymers, usually referred to as biopolymers, are made by living organisms. Common examples of biopolymers are cellulose, a carbohydrate made only by plants (see Textbox 53) collagen, a protein made solely by animals (see Textbox 61), and the nucleic acid DNA, which is made by both plants and animals (see Textbox 64). 

Gelatin is a biopolymer it is denaturated collagen. Due to its natural origin, differences exist between the molecular composition... 

Although it seems obvious that there is a coimection between the natural origin of a polymer and its biodegradabihty this is one of the most common misunderstandings with respect to biopolymers. Biodegradabihty is a function of the chemical structure of a molecule and there is no dependence on its origin. This is the reason why synthetic, man-made polymers can also be biodegradable if their structure obeys certain rules. 

This chapter provides a brief overview of a variety of biopolymers of natural origin available for the use as shell or coating materials in microencapsulation of actives. However, a detailed knowledge of the chemical and physical properties of the encapsulation material is required prior to use as a coating/tilm/matrix during the encapsulation process. The interaction between encapsulation material and actives needs careful consideration. Also, the economic considerations will remain crucial for the selection of the most appropriate encapsulant materials. 

Most of the enzymatically resorbable biopolymers discussed above have a natural origin. Nevertheless, in order to improve the resorption profile of the synthetic hydrolytically resorbable biopolymers, studies have been undertaken to identify those enzymes that are able to catalyze the resorption of synthetic biopolymers. 

Biopolymers are often used throughout the human body they are also called biomedical polymers. A biomedical material can be of natural origin (biopolymer) or a synthetic polymer and can be used for any period of time, as a whole or as part of a system that treats, augments, or replaces any organ or function of the body, as well as for medical technical applications outside the body. When a prosthetic device is placed into the body, two aspects must be taken into account functional performance and biocompatibility. The former requires special functions of the biomedical polymers, in particular including load transmission and stress distribution. Biocompatibility between a polymer and a biological system (e.g., soft tissue,... 

There is no question of denying the importance of natural polymers of mineral origin. Nevertheless, they will be overlooked in this textbook in favor of natural organic polymers (also called biopolymers) that originate from vegetable or animal sources, some of them being even found in both worlds. 

Polymers from natural origin, such as polysaccharides for instance, are of great interest in pharmaceutical sciences since they are considered generally as safe materials. The formulation of these biopolymers into particles often occurs in an aqueous medium and as such the following processes can be regarded as environment friendly, and safe for human health. 

Biopolymers from natural origins include, from a chemical point of view, six sub-groups ... 

Natural circular dichroism (optical activity). Although circular dichroism spectra are most difficult to interpret in terms of electronic structure and stereochemistry, they are so very sensitive to perturbations from the environment that they have provided useful ways of detecting changes in biopolymers and in complexes particularly those remote from the first co-ordination sphere of metal complexes, that are not readily apparent in the absorption spectrum (22). It is useful to distinguish between two origins of the rotational strength of absorption bands. 

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