title: Synthesis and swelling properties of novel pH-sensitive poly(aspartic acid) gels.
abstract: Chemically cross-linked poly(aspartic acid) (PASP) gels were prepared by the hydrolysis of poly(succinimide) (PSI). The latter was prepared by thermal polycondensation of aspartic acid. The PSI chains were cross-linked by natural amines and amino acid derivatives such as putrescin, spermine, spermidine, lysine and cystamine to obtain biodegradable, biocompatible, amino acid-based hydrogels. The volume of the synthesized unhydrolyzed PSI gels changes abruptly at a well-defined pH that results in ring opening, while the hydrolyzed gels show a volume phase transition around the pK values of PASP. The unidirectional stress-strain behavior of the gels as well as the dependence of equilibrium swelling degree on the pH was carefully studied and the most important network parameters were determined by a modified version of the Brannon-Peppas-Peppas theory.
authors.affiliation: Department of Physical Chemistry and Material Sciences, Budapest University of Technology and Economics, Laboratory of Soft Matters, H-1521 Budapest, Hungary.
authors.forename: Tamás
authors.initials: T
authors.lastname: Gyenes
authors.forename: Viktória
authors.initials: V
authors.lastname: Torma
authors.forename: Benjámin
authors.initials: B
authors.lastname: Gyarmati
authors.forename: Miklós
authors.initials: M
authors.lastname: Zrínyi
mesh_terms: D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000138:chemical synthesis / Q000737:chemistry; D001672:Biocompatible Materials / Q000737:chemistry; D003432:Cross-Linking Reagents / Q000494:pharmacology; D003538:Cystamine / Q000494:pharmacology; D004220:Disulfides / Q000737:chemistry; D004548:Elasticity / Q000187:drug effects; D005782:Gels / Q000138:chemical synthesis* / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis / Q000187:drug effects; D008239:Lysine / Q000494:pharmacology; D010455:Peptides / Q000138:chemical synthesis* / Q000737:chemistry*; D012995:Solubility / Q000187:drug effects; D012996:Solutions; D013696:Temperature
chemical_list: D001672:Biocompatible Materials; D003432:Cross-Linking Reagents; D004220:Disulfides; D005782:Gels; D010455:Peptides; D012996:Solutions; C017645:polyaspartate; C025252:poly-DL-succinimide; D001224:Aspartic Acid; D008239:Lysine; D003538:Cystamine