Thermal cross-linking for biologically degradable materials. Preliminary report.
To diminish undesirable side effects of chemical cross-linking of biodegradable materials, the authors developed a thermal cross-linking method that involved esterification by dehydration under dry conditions. The optimal condition for cross-linking was heating at 130-140 degrees C for 40 hr. Efficacy of the cross-linking was evaluated using enzymatic digestion of 0.01% protease in phosphate buffer at pH 7.4. Collagenous materials without cross-linking were digested completely within 30 min. However, with thermal cross-linking, it required 7 days for digestion. The capacity for holding onto water also was tested. Water content decreased when the cross-link density was increased. As an in vivo experiment, six succinylated collagen sealed vascular grafts treated with thermal cross-linking were implanted in the abdominal aortae of dogs and removed 21 days later. These grafts showed no foreign body reaction, and the collagen layer was almost completely absorbed. A collagen sealed graft cross-linked with formaldehyde used as a control showed a strong foreign body reaction. These results suggest that the physical cross-linking method was suitable for biodegradable biologicals, such as collagenous materials, without the undesirable side effects of chemical cross-linking regents.
Ma
X H
XH
First Department of Surgery, Yokohama City University, School of Medicine, Japan.
Noishiki
Y
Y
Yamane
Y
Y
Iwai
Y
Y
Marato
D
D
Matsumoto
A
A
D000818:Animals; D001012:Aorta, Abdominal / Q000601:surgery; D001672:Biocompatible Materials; D001807:Blood Vessel Prosthesis; D003094:Collagen; D003432:Cross-Linking Reagents / Q000009:adverse effects; D004285:Dogs; D005557:Formaldehyde / Q000009:adverse effects; D006358:Hot Temperature; D008422:Materials Testing; D013499:Surface Properties; D014867:Water
D001672:Biocompatible Materials; D003432:Cross-Linking Reagents; D014867:Water; D005557:Formaldehyde; D003094:Collagen