Biomedical applications, aliphatic polyesters

Aliphatic polyesters have received great interest for potential biomedical application. Polythioesters (polyesters in which one of the oxygen atoms of the ester groups has been replaced by a sulfur atom) have received less attention, although these materials are expected to show interesting material properties such as higher... 

This review aims at reporting on the synthesis of aliphatic polyesters by ROP of lactones. It is worth noting that lactones include cyclic mono- and diesters. Typical cyclic diesters are lactide and glycolide, whose polymerizations provide aliphatic polyesters widely used in the frame of biomedical applications. Nevertheless, this review will focus on the polymerization of cyclic monoesters. It will be shown that the ROP of lactones can take place by various mechanisms. The polymerization can be initiated by anions, organometallic species, cations, and nucleophiles. It can also be catalyzed by Bronsted acids, Lewis acids, enzymes, organic nucleophiles, and bases. The number of processes reported for the ROP of lactones is so huge that it is almost impossible to describe aU of them. In this review, we will focus on the more... 

Malberg S, Plikk P, Fiime-Wistrand A, Albertsson A-C (2010) Design of elastomeric homo-and copolymer networks of functional aliphatic polyester for use in biomedical applications. Chem Mater 22 3009-3014... 

Aliphatic polyesters are an attractive class of polymer that can be used in biomedical and pharmaceutical applications. One reason for the growing interest in this type of degradable polymer is that their physical and chemical properties can be varied over a wide range by, e.g., copolymerization and advanced macro-molecular architecture. The synthesis of novel polymer structures through ringopening polymerization has been studied for a number of years [1-5]. The development of macromolecules with strictly defined structures and properties, aimed at biomedical applications, leads to complex and advanced architecture and a diversification of the hydrolyzable polymers. 

Aliphatic polyesters are, together with polycarbonates, polyanhydrides, and poly(amino acids), the most well-known synthetic hydrolyzable polymers. They are often prone to degradation but are at the same time usually not good enough for technical applications. A renewed interest in aliphatic polyesters has resulted in developing new materials important in the biomedical and ecological fields. 

When aliphatic polyesters are considered, lack of functional groups along the chains is a severe limitation for their application in the biomedical field or as environmentally... 

Aliphatic polyesters (such as PLA, polyglycolic acid and their copolymers) are the most important class of biocompatible polymers used in biomedical applications. This class of polymers has shown superior properties over conventional polymers, such as excellent biocompatibility, biodegradation, and thermal, physical and mechanical properties, which make them suitable for applications in drug delivery and tissue engineering [19-21]. 

Polyesters can be synthesized either by ring-opening polymerization (ROP) or polycondensation. Both of these approaches have merit in the manipulation of properties of degradable polymers. Commercially, ROP is the most widely used practice for the synthesis of PHAs for consumer applications due to the ease of scale up, acceptable purity, and cost considerations. However, for biomedical applications where cost pressures are low and purity and function are paramount, condensation polymerization can yield superior outcomes [20]. Although the class of degradable polymers is rather large and includes poly(butyrolactones), poly(dioxanone), aliphatic poly(carbonates), poly(anhydrides), and poly(hydroxyalkanoates), the focus of the subsequent sections will be on the PGA, PLA, and poly(caprolactone) (PCL) family of polymers, as these are the most widely used polymers in both medical and consumer products arena. 

H. Seyednejad, et al., Functional aliphatic polyesters for biomedical and pharmaceutical applications, J. Control. Release 152 (1) (2011) 168-176. 

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... 

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