Sutures, biodegradable

Supernatants, sedimentation and, 22 50 Superoxide absorbable suture, biodegradation and, 24 220 Superoxide dismutase (SOD) enzymes, 13 297... 

Ah these interesting characteristics have led to the development of numerous applications of chitosan and its derivatives not only in biomedicine such as surgical sutures, biodegradable sponges and bandages [143], matrices (in microspheres, microcapsules, membranes and compressed tablets) for the delivery of drugs [147], but also in orthopaedic materials and dentistry [148]. 

Here we restrict our discussion to the use of polymer materials as nerve conduit. To select proper polymer materials, there are some general requirements which all nerve conduits should follow easily formed into a conduit with desired dimensions sterilizable tear resistant easy to handle and suture biodegradable etc (101),... 

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). 

Despite the universal use of sutures for wound closure, there is a need to utilize adhesives instead, because of their ease of use and the reduced risk of infection. Alkyl cyanoacrylate adhesives have been studied extensively for this use, and a significant amount of research has been performed to evaluate their interaction with living tissue [40,41 J. They have been approved for external use only, because of concerns with the fact that the polymers do not readily biodegrade and can cause inflammation around the area to which it was applied. However, these concerns are reduced for -butyl cyanoacrylate, as compared to the ethyl cyanoacrylate. There is even some evidence that their use as liquid sutures actually reduces the rate of infection around the healing wound or surgical incision [42J. 

Polymers are a fundamental part of the modem world, showing up in everything from coffee cups to cars to clothing. In medicine, too, their importance is growing for purposes as diverse as cardiac pacemakers, artificial heart valves, and biodegradable sutures. 

Sei f-Tfst 19.4A (a) Write the formula for the monomer of the polymer sold as Teflon, — (CF2CF2),—. (b) The polymer of lactic acid (16) is a biodegradable polymer made from renewable resources. It is used in surgical sutures that dissolve in the body. Write the formula for a repeating unit of this polymer. 

Y Irradiation has proven useful for many lactide/glycolide formulations. This again is an extension of technology from the biodegradable suture field. The appropriate dose of y irradiation must be determined for each new drug delivery product (57). The D value, the amount of irradiation in Mrads needed to achieve a 90% reduction in the microorganism population, can be determined from Eq. (1) ... 

While this book is focused on drug delivery, the value of biodegradable polymers is not limited to this field. Biodegradable polymers will be useful in other areas of medical therapeutics, such as sutures and bone plates and other types of prostheses. The polymers will also be useful in nonmedical fields, for disposable plastics, bottles, diapers and many other entities. 

If the homopolymer decomposes at the fabrication temperature another approach is to make a copolymer that can be melt processed at a lower temperature. For example, polyhydroxybutyrate decomposes at the processing temperature (190°C), whereas the copolymer with valeric acid can be processed at 160°C without decomposition. These aliphatic polyesters are biodegradable and most importantly, the decomposition products are not toxic, hence their use in medical applications (e.g., sutures). 

Common biodegradable polymers for medical devices are constructed from synthetic linear aliphatic polyesters. One material commonly used for internal sutures is poly(glycolic acid) (PGA). PGA is synthesized from the dimer of glycolic acid (Fig. 13.1.l). 1... 

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