Bioabsorbable polymers application

Bioabsorbable polymers such as aliphatic polyesters from the poly ((z-hydroxy acids) family, especially polylactic acid (PLA), are well known bioabsorbable materials and are widely used for biomedical applications... 

Biodegradable or bioabsorbable polyesters including PLAs can be applied as biomedical materials [41]. Table 8.11 [4] shows the functions and purposes of bioabsorbable polymers. Bioabsorbable biomedical materials should be nontoxic, effective, sterilizable and biocompatible. In addition, bioabsorbable biomedical materials should have the appropriate degradation rate required for each application (Figure 8.27 [13]). 

Table 8.11 Medical applications of bioabsorbable polymers 14], (Reproduced with permission from ref. [41. Copyright 2000 Wiley-VCH Verlag GmbH, Weinheim.)...

Tormala P.,PohjonenT. and Rokkanen P. (1998),Bioabsorbable polymers Materials technology and surgical applications, Jourrud of Engineering in Medicine, 1 February 1998,212 (2), 101-111. 

A second application is the controlled release of the polymer. Here, we report two different examples. The first example is a bioabsorbable suture. A suture is defined as bioabsorbable in solid polymeric materials or devices if it can dissolve in body fluids without any polymer chain cleavage or molecular mass decrease. Another example is a water-soluble implant that undergoes slow dissolution in body fluids. A bioabsorbable polymer also can be bioresorbable if the dispersed macromolecules are excreted [6]), or it is a MD belonging at least to class 11b [4] but usually to class 111 (release a drug with an ancillary function or it is completely resorbable) [5],... 

K. Gorona, S. Gogolewski, Novel biodegradable polyurethanes for medical applications, in Synthetic Bioabsorbable Polymers for Implants, ed. by C.M. Agrawal, J.E. Parr, S.T. Lin (ASTM special technical publication, UK, 2000), pp. 39-57... 

Hie ester linkage of aliphatic and aliphatic-aromatic copolyesters can easily be cleaved by hydrolysis under alkaline, acid, or enzymatic catalysis. This feature makes polyesters very attractive for two related, but quite different, applications (i) bioresorbable, bioabsorbable, or bioerodible polymers and (ii) environmentally degradable and recyclable polymers. 

Some of the most important water-soluble polymers belong to the family of polysaccharides. Soluble polysaccharides were discussed in a review by Franz on polysaccharides in pharmaceutical formulations. Due to their industrial importance, key characteristics and typical applications of those polysaccharides are listed in Table 3. In addition to those noted in Table 3, the oxidation of cellulose (to convert 16-24% of its primary hydroxyl groups to carboxyl groups) produces oxidized cellulose, a fibrous white powder. It is used as a bioabsorbable hemostatic agent. The bioabsorption may be partly attributed to solubilization through the carboxylate moieties. 

Because CDs are nontoxic, biodegradable, and bioabsorbable, they may be used in medical applications, as well as providing for the fabrication of more environmentally responsible polymer materials. In this report we have summarized almost exclusively our own recent studies employing the cyclic starch derivatives called cyclodextrins to both nanostructure and functionalize polymer materials. Lest the reader gets the erroneous impression that our studies have been carried out in isolation, we refer to a recent review [120], and a summary [121], describing related... 

Poly(butylene succinate) (PBS) is an important member of biodegradable aliphatic polyester family. PBS and related copolymers have shown considerable promise for uses as environmentally biodegradable thermoplastics, as well as bioabsorbable/biocompatible medical materials (/). In both cases, practical applications require that the polymer possess a high molecular weight (M >20,000) so that it can have useful mechanical properties. 

Poly(4-hydroxybutyrate) [P(4HB)] is a highly ductile, flexible polymer withstanding an extension of around 1,(XX)% before breaking, compared to P(3HB), which can only extend to less than 10% before breaking. Combining these different monomers to form copolymers, as in P(3HB-co-4HB), been described as one of the most useful PHAs by Sudesh et al. [5], produces a family of materials with mechanical properties that can be tailored to specific needs. P(3HB-co-4HB) has been found to have desirable mechanical properties for applications in the medical and pharmaceutical field [11]. The biocompatibility and bioabsorbable nature of P(3HB-co-4HB) makes it the most valuable type of biopolymer among the vast number of different PHAs synthesized by microorganisms. To date, five wild-type bacteria, which can produce P(3HB-co HB), i.e. R. eutropha... 

PGA was used to produce the first example of bioabsorbable synthetic suture threads under the commercial name of Dexon, although the mechanical strength of such devices decreased in a short period of time (2-4 weeks) (Ratner, 2004), limiting the application of this polymer. In order to improve PGA mechanical characteristics, PGA and PLA copolymers were realized PLA is hydrophobic and limits water uptake, slowing the hydrolysis mechanism... 

To be used as biomaterials, polymers must possess biocompatibility, bioabsorbability and mechanical resistance [114]. Current applications include surgical implants and plain membranes in vascular or orthopaedic surgery, as well as the controlled release of drugs. PLA is the most widely used material for medical applications. Other possible outlets are offered by the hygiene sector including, nappy back sheets, cotton swabs, disposable razors and so on. 

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