• Dyksterhuis, Leanne
• Elvin, Christopher
• Werkmeister, Jerome
• Vuocolo, Tony
• Ramshaw, John

Abstract

Collagen has proved a safe and effective biomaterial and a range of successful devices are now in regular clinical use.In some forms, such as sponges and membranes for wound management, the collagen is purified and reconstituted, generally followed by chemical stabilisation to enhance the mechanical stability and increase the rate of resorption.In other cases, such as bioprosthetic heart valves, tissues are used in their natural shape and size after chemical stabilisation, which minimises immunogenicity and enhances implant lifetime.Traditionally, glutaraldehyde has been used as the crosslinking agent, but this is considered to have drawbacks, particularly its potential cytotoxicity and its propensity to increase calcification [1] Previously we have shown the utility of a photo-crosslinking method for crosslinking proteins solutions, including fibrinogen [2] and gelatin [3,4].The method uses a combination of RuII(bipy)3Cl2, sodium persulfate (SPS) mixed with the protein, followed by irradiation with light, preferably at 450nm [5]. In the present study, we have examined the utility of the photo-crosslinking method to stabilise tissues rather than protein solutions.A range of different tissues with differing compositions and conformations have been examined, including tendon, collagen membrane, lens capsule and heart valve.The effects of varying the soaking time before light irradiation and the concentrations of the RuII(bipy)3Cl2 and SPS reagents have been studied.The effectiveness of the crosslinking has been examined using hydrothermal isometric tension measurements and biochemical analyses. These data show that the photo-crosslinking is effective for crosslinking tissue samples, although at higher concentrations of SPS the extent of oxidative degradation can exceed the extent of photo-crosslinking.The observed cross-linking is based, as in the previous solution studies, on the formation of bis-tyrosine cross-links.Clearly, given the need for light in the cross-linking process, the method is limited to thin tissue samples, such as those in the present study, and would not suitable for thick samples.

Topics

• impedance spectroscopy
• Sodium