In Vitro and In Vivo Characterization of Biodegradable Poly(organophosphazenes) for Biomedical Applications

Biodegradable Polyphosphazene Scaffolds for Tissue Engineering

“…The polymer degradation rate can be varied from a few hours to years based on the side groups chosen for polymer backbone substitution. Various side-group combinations resulted in numerous biodegradable polyphosphazenes with a wide range of degradation time and physicochemical properties suitable for a variety of biomedical applications (Allcock, 2001;Heyde and Schacht, 2004;Kumbar et al, 2006). For example, SCHEME 1 Generalized degradation pathway for amino acid ester-substituted polyphosphazenes.…”

“…A variety of polyphosphazenes from biostable to biodegradable have been reported so far for various biomedical applications (Allcock, 2006;Heyde and Schacht, 2004;Laurencin and Ambrosio, 2003). Biodegradable phosphazenes with hydrolytically sensitive side groups such as amino acid ester, glucosyl, glycerol, lactide, and glycolide esters have raised broad interest as biomaterials for tissue engineering and drug delivery applications (Allcock, 2001;Kumbar et al, 2006;Laurencin et al, 2005;Nair et al, 2003). Controlled degradation and the degradation behavior modulation (surface vs. bulk) associated with nontoxic degradation products caused biodegradable polyphosphazenes to become a potential class of biomaterials for tissue engineering.…”

“…The ideal scaffold should exhibit biocompatibility, biodegradability, mechanical compatibility, interconnected porosity, and the nontoxic nature of the degradation products (Hollister, 2005;Hutmacher, 2001). Biodegradable polyphosphazenes were proven to be biocompatible in vitro and in vivo with nontoxic degradation products Kumbar et al, 2006;Laurencin et al, 1993) In addition, the mechanical properties are tunable to match a tissue of interest. Therefore, biodegradable polyphosphazenes are a promising class of biomaterials for scaffold-based tissue engineering.…”

“…So far, reviews in the literature have dealt only with the synthetic flexibility and biocompatibility of various biodegradable polyphosphazenes (Allcock, 2001;Allcock et al, 2002;Heyde and Schacht, 2004;Kumbar et al, 2006;Laurencin et al, 2003;Luten et al, 2003;Nair et al, 2003;Singh et al, 2007). However, in this chapter we cover biodegradable polyphosphazenes as scaffold materials for tissue engineering.…”

Poly‐ and Cyclophosphazenes as Drug Carriers for Anticancer Therapy

“…In particular, since polymeric drug delivery systems have attracted much attention recently as a major emerging nanobiotechnology for polymer therapy, extensive studies have been directed at new drug delivery systems from polyphosphazenes by many research groups in various fields. For example, polyphosphazene micelles Chang et al, 2002Chang et al, , 2005Zhang et al, 2005aZhang et al, , b, 2006 and hydrogels (Allcock and Ambrosio, 1996;Allcock and Pucher, 1991;Kang et al, 2006a, b;Lee et al, 2002;Seong et al, 2005) were prepared for sustained release of hydrophobic and small-molecular drugs, biodegradable microspheres, and matrices (Andrianov, 2006;Andrianov and Payne, 1998;Andrianov et al, 2004a, b;Caliceti et al, 2000;Kumbar et al, 2006;Lakshmi et al, 2003;Nair et al, 2004;Veronese et al, 1998) for protein and vaccine delivery, cationic polyphosphazenes for gene delivery (de Wolf et al, 2005(de Wolf et al, , 2007Luten et al, 2003), and thermosensitive poly and cyclophosphazenes (Jun et al, 2006;Kim, J.I. et al, 2004;Lee et al, 1999a, b;Song et al, 1999;Toti et al, 2007) for controlled release of anticancer drugs.…”