Medical applications structure

Silicone mbbers have been widely used for medical applications, particularly for body implants in structural cosmetic surgery. One high-profile application has been that of breast implants, but the award in early 1994 of enormous damages by a US court in respect of faulty implants may discourage development of this application. 

Using MRI as a substitute for X-ray tomography is only the first of what are many medical applications. More lie on the horizon. If, for example, the rate of data acquisition could be increased, then it would become possible to make the leap from the equivalent of still photographs to motion pictures. One could watch the inside of the body as it works— see the heart beat, see the lungs expand and contract—rather than merely examine the structure of an organ. 

The reduced symmetry of the chromophore, which still contains 187t-electrons and is therefore an aromatic system, influences the electronic spectrum which shows a bathochromic shift and a higher molar extinction coefficient of the long-wavelength absorption bands compared to the porphyrin, so that the photophysical properties of the chlorins resulting from this structural alteration render them naturally suitable as pigments for photosynthesis and also make them of interest in medical applications, e.g. photodynamic tumor therapy (PDT).2... 

Medical applications of alkaloids have led to the production of drugs and drug components. They can be based on pure natural alkaloids, as in the case of extracts. Purified alkaloids, partially and even totally synthesized compounds based on the natural alkaloid structure, are also used. Chemically modified alkaloids are yet another example. Chemically modifying the structure affects biological activity. The general trend in modern medicine is to develop compounds that are biologically more active than those found in nature. This is achieved in many cases by alkaloid modifications and synthesis. However, natural compounds themselves are very important because they are the basis for artificial drugs. Moreover, alkaloids used as natural products are important... 

Figure 1.4. Structure of clomiphene and tamoxifen, two non-steroidal synthetic anti-oestrogens that have found medical application...

For the synthesis of highly defined polysaccharides, glucosylsaccharides are the only option available. Specialized oligo- and polysaccharides for food and medical applications can be synthesized, and also hybrid structures with non-natural macromolecules or surfaces. 

Many polymer-polymer complexes can be obtained by template polymerization. Applications of polyelectrolyte complexes are in membranes, battery separators, biomedical materials, etc. It can be predicted that the potential application of template polymerization products is in obtaining membranes with a better ordered structure than it is possible to obtain by mixing the components. The examples of such membranes from crosslinked polyCethylene glycol) and polyCacrylic acid) were described by Nishi and Kotaka. The membranes can be used as so-called chemical valves for medical applications. The membranes are permeable or impermeable for bioactive substances, depending on pH. 

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