title: Novel biodegradable polyphosphate cross-linker for making biocompatible hydrogel.
abstract: To obtain a novel biodegradable cross-linker, polymerizable polyphosphate (PIOP) was synthesized by ring-opening polymerization of 2-i-propyl-2-oxo-1,3,2-dioxaphospholane with 2-(2-oxo-1,3,2-dioxaphosphoroyloxyethyl methacrylate) (OPEMA). The number averaged molecular weight of the PIOP was 1.2 x 10(4), and the number of OPEMA units in one PIOP molecule was 2.2. Nonenzymatic degradation of the PIOP was evaluated in various pH aqueous media. The degree of hydrolysis was dependent on the pH; that is, it increased with an increase in the pH of the medium. At pH 11.0, the PIOP completely degraded in only 6 days. The poly[2-methacryloyloxyethyl phosphorylcholine (MPC)] cross-linked with the PIOP was prepared by radical polymerization. This polymer could form hydrogel, and the free water fraction in the hydrogel was high. The enzymatic activity of trypsin in contact with the hydrogel was similar to that in buffer solution. There is no adverse effect caused by the hydrogel to reduce the function of the trypsin. The cytotoxicity of poly(MPC) and degraded PIOP was evaluated using v79 cells, and it was not observed in either case. In conclusion, PIOP is a hydrolyzable polymer, which can be used as a cross-linker, and novel hydrogels having biodegradability and biocompatibility were prepared from poly(MPC) cross-linked with the PIOP.
authors.affiliation: Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10 Kanda-surugadai; Chiyoda-ku, Tokyo 101-0062, Japan. yasu.org@tmd.ac.jp
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Iwasaki
authors.forename: Chigusa
authors.initials: C
authors.lastname: Nakagawa
authors.forename: Michiko
authors.initials: M
authors.lastname: Ohtomi
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Ishihara
authors.forename: Kazunari
authors.initials: K
authors.lastname: Akiyoshi
mesh_terms: D000818:Animals; D001672:Biocompatible Materials; D001673:Biodegradation, Environmental; D002460:Cell Line; D006224:Cricetinae; D003412:Cricetulus; D003432:Cross-Linking Reagents / Q000737:chemistry* / Q000494:pharmacology; D005347:Fibroblasts / Q000187:drug effects; D020100:Hydrogels; D011122:Polyphosphates / Q000737:chemistry* / Q000494:pharmacology
chemical_list: D001672:Biocompatible Materials; D003432:Cross-Linking Reagents; D020100:Hydrogels; D011122:Polyphosphates