title: Fixation of bioprosthetic tissues with monofunctional and multifunctional polyepoxy compounds.
abstract: Collagen from a native tissue is fixed with a polyepoxy compound (PC) for use as a new biologic prosthetic material. Prior studies have shown that this biomaterial has comparable properties with collagen fixed with glutaraldehyde (GA), and thus has great promise for biomedical applications. A prior kinetic study indicated that the reaction between the functional groups of collagen and the multifunctional epoxy EX-313 is a 2.5th-order reaction. The purpose of this study was to understand the mechanism of the amino acid-PC reactions in a fixation process. Bovine arteries were fixed with a monofunctional PC (EX-131) and a multifunctional PC (EX-313) as a function of fixation time. A sequential fixation with a second fixative was used to identify the available remaining reactive sites from a prior fixation. The denaturation temperature (Td) was measured on each sample. Because the denaturation temperature is a direct indication of crosslinking of individual amino acids with the fixative, the increase in Td of a subsequent fixation may be indicative of the available remaining amino acids. The fixation index was measured on each sample to reflect the increase of fixation completion in a sequential fixation process. The fixation index and crosslink data also revealed that the reactive amino acids for EX-131 and EX-313 may not be exactly the same. The data in this study suggest that a monofunctional fixative can pre-react with the amino acids of collagen to effectively block further fixation of collagen with a second fixative. This amino acid masking may be associated with collagen branching. Collagen branching and its effect on denaturation temperature are described.
authors.affiliation: TU Bioscience Labs, Tustin, California 92680.
authors.forename: R
authors.initials: R
authors.lastname: Tu
authors.forename: S H
authors.initials: SH
authors.lastname: Shen
authors.forename: D
authors.initials: D
authors.lastname: Lin
authors.forename: C
authors.initials: C
authors.lastname: Hata
authors.forename: K
authors.initials: K
authors.lastname: Thyagarajan
authors.forename: Y
authors.initials: Y
authors.lastname: Noishiki
authors.forename: R C
authors.initials: RC
authors.lastname: Quijano
mesh_terms: D000818:Animals; D001705:Bioprosthesis; D001807:Blood Vessel Prosthesis; D002417:Cattle; D003094:Collagen / Q000737:chemistry; D003432:Cross-Linking Reagents; D004852:Epoxy Compounds; D005404:Fixatives; D066298:In Vitro Techniques; D008422:Materials Testing; D011126:Polypropylenes; D013895:Thoracic Arteries / Q000737:chemistry
chemical_list: D003432:Cross-Linking Reagents; D004852:Epoxy Compounds; D005404:Fixatives; D011126:Polypropylenes; C050906:polyglycerol polyglycidyl ether; D003094:Collagen; C089000:Denacol EX-131