title: Biodegradation of unsaturated poly(ester-amide)s and their hydrogels.
abstract: The biodegradability of both unsaturated (UPEA) and saturated (SPEA) poly(ester-amide)s and a series of hydrogels (UPEA-G) fabricated from UPEA and poly(ethylene glycol) diacrylate (PEG-DA) was examined as a function of PEA chemical structures in both phosphate buffered saline (PBS) and alpha-chymotrypsin solutions. Based on the weight loss data, alpha-chymotrypsin had a much more profound effect on the hydrolyses of UPEA, SPEA polymers (up to 32% weight loss on day 1 for FPBe) and UPEA-G hydrogels (up to 32% weight loss on day 31 for FPBe-G28) than a PBS buffer (less than 10% for polymers and 16% for hydrogels). The changes in elastic moduli and the interior morphology of the hydrogels in both PBS buffer and alpha-chymotrypsin solutions were also monitored for 2 months, and the hydrogels' crosslinking density (n(e)) and molecular weight between crosslinks (M(c)) before and after biodegradation were then examined as a function of biodegradation time, enzyme concentration, and different chemical structure of precursors. The differences in biodegradation rates among PEA polymer and UPEA-G hydrogels are ascribed to differences in hydrophilicity and saturated or unsaturated structure of the polymers and hydrogel precursors. Our results showed that, by changing the concentration of alpha-chymotrypsin, the type of UPEA precursors and their feed ratio, the UPEA-G hydrogels could have controllable biodegradability, which is quite desirable for a wide range of biomedical and pharmaceutical applications.
authors.affiliation: Fiber and Polymer Science Program, Department of Fiber Science and Apparel Design, and Biomedical Engineering Program, Cornell University, Ithaca, NY 14853-4401, USA.
authors.forename: Kai
authors.initials: K
authors.lastname: Guo
authors.forename: Chih-Chang
authors.initials: CC
authors.lastname: Chu
mesh_terms: D000577:Amides / Q000737:chemistry*; D001672:Biocompatible Materials / Q000737:chemistry*; D001673:Biodegradation, Environmental; D002918:Chymotrypsin / Q000737:chemistry; D004798:Enzymes / Q000737:chemistry; D020100:Hydrogels / Q000737:chemistry; D006859:Hydrogen / Q000737:chemistry*; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D008956:Models, Chemical; D015394:Molecular Structure; D011091:Polyesters / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry; D013997:Time Factors
chemical_list: D000577:Amides; D001672:Biocompatible Materials; D004798:Enzymes; D020100:Hydrogels; D011091:Polyesters; D011108:Polymers; D006859:Hydrogen; D002918:Chymotrypsin; C117608:alpha-chymotrypsin