A MODEL TO DETERMINE MICROWAVE-STIMULATED CROSS-LINKING OF COLLAGEN USING DILUTED GLUTARALDEHYDE SOLUTIONS

The model presented shows the effect of various fixation conditions on glutaraldehyde (GA) cross-linking of collagen. The model consists of 10 very thin (10 mum) synthetic collagen sheets, and by determining th e degree of cross-linking from the outer two sheets to the core region one can study the quality of fixation. The extent of cross-linking is assessed by measuring the shrinkage temperature (Ts) of each separate sheet. The degree of cross-linking and the distribution of cross-link s is visualized by plotting the Ts against the position of the sheet w ithin the model, thus forming Ts profiles. Experiments were carried ou t to study the effect on the degree of cross-linking of short-term mic rowave-stimulated fixation (5 min, 45-degrees-C) using low GA concentr ation (0.1 %) and of a combination of GA presoaking at low or room tem perature, (0-degrees-C) followed by short-term (<3 min) heating to 45- degrees-C. Short-term fixation at 45-degrees-C caused an increase in T s of more than 10-degrees-C in the central sheets and more than 20-deg rees-C in the outer sheets. Presoaking the samples at room temperature for 1 h or at 0-degrees-C for 3 h, with subsequent short-term heating to 45-degrees-C, caused an almost equal rise in Ts throughout the col lagen sheets. We conclude that a homogeneous fixation is obtained by t he combination of presoaking at low temperature, followed by short-ter m microwave irradiation to 45-degrees-C.