Bioresorbable polymers polymer synthesis

Polyammonium-containing ligands, 24 44 Polyammonium macropolycycles, 76 780 Polyampholytes, 20 475 479 solution properties of, 20 479 synthesis of, 20 477- 478 Poly(anhydrides), bioresorbable polymers, 3 740... 

When designing a medical device based on a bioresorbable polymer, the degradation ability of the material during all the phases from the synthesis to the complete resorption in vivo must be carefully considered. In this regard, synthetic polymers are more versatile compared to natural origin polymers, thereby allowing a finer control of the theoretical degradation rate. However, this rate depends from a number of external factors such as production process conditions (eg, humidity, temperature) and site of implantation (eg, pH, mechanical stress) [13—18]. 

To satisfy the requirements of biocompalibility and biodegradability, the materials used in medical and pharmaceutical fields for intravenous injection are generally characterized by polymeric NPs based on polyesters, which are biocompatible and biodegradable. In this chapter, we cover the most common bioresorbable polymer materials that are synthesized. Then, we discuss the methods adopted for the synthesis of NPs made of bioresorbable polymers. Finally, we present the most common applications of bioresorbable polymer NPs in medical and pharmaceutical fields and the hurdles involved in their use. 

A plethora of bioresorbable polymer materials are adopted for medical and pharmaceutical applications. Among them, aliphatic polyesters, polycarbonates, poly (amino acids), and polyphosphoesters are the main representatives. For the synthesis of NPs, aliphatic polyesters are the most adopted materials. Data on a huge number of different polyesters can be found in the literature, but this chapter focuses on the main polyesters poly (lactic acid) (PLA), poly(glycolic acid) (PGA), polycaprolactone (PCL), and their copolymers [4]. 

Various copolymers with a high PDO content have been synthesized and studied to improve the mechanical performance and increase the rate of resorption [40]. A copolymer with 80 % PDO and up to 20 % PGA has a resorption profile similar to Dexon and Vicryl and yet maintains a compliance similar to PDS . The copolymer with 85 % PDO and up to 15 % PLLA exhibits higher compliance and a lower modulus than the PDO homopolymer, yet its resorption profile is similar to PDS [41]. Copolymers with three or more different monomer units have also been explored. One such example is poly(GA-co-PDO-co-LA), which has been proposed as a possible suture material with suitable crystallinity, good flexibility, better strength retention, and a reasonably rapid resorption rate [42]. Until recently, there was not much interest in developing PDO as a biomaterial, mainly because of the lack of commercial availability and difficulties in its synthesis. However, with the development of new alternative synthesis procedures and the availability of the PDO monomer, there has been more commercial interest in developing PDO as a bioresorbable polymer in recent years (Table 4.6). 

The term bioresorbable refers to polymers which degrade into products that can be eliminated from the body through natural pathways or, even better, which are involved normally in metabolic pathways [13]. Toxicity does not necessarily stem from the polymer itself or its fragments, but may arise from the presence of synthesis residues such as solvents, catalysts, monomers, and stabilizers [80]. 

Oledzka E., Sobezak M. 2012. Polymers in the pharmaceutical applications Natural and bioactive initiators and catalysts in the synthesis of biodegradable and bioresorbable polyesters and polycarbonates. In Innovations in Biotechnology. Edited by Dr. Eddy C. Agbo. Publisher InTech. 

Kharas, G. B., Kamenetsky, M., Simantirakis, J., Beinlich, K., C, Rizzo, A.-M., T., Caywood, G., A. Watson, K. 1997. Synthesis and characterization of fumarate-based polyesters for use in bioresorbable bone cement composites. Journal of Applied Polymer Science, 66, 15. 

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