A multi-sample denaturation temperature tester for collagenous biomaterials

The temperature at which collagen denatures from a triple helix to a random coil structure is a useful measure of the degree of crosslinking. A new multi-sample denaturation temperature tester (DTT) has been constructed for rapid determination of the collagen denaturation temperature of natural tissues and collagenous biomaterials. To validate the system, the denaturation temperatures measured for the DTT are compared with results from differential scanning calorimetry (DSC). Data are presented for bovine pericardium in three states with denaturation temperatures ranging from 68 to 85 degrees C: fresh, or crosslinked with glutaraldehyde or the epoxide reagent Denacol EX-512 poly (glycidyl ether). Denaturation temperatures measured by DTT were not significantly different from those measured by differential scanning calorimetry (DSC); however, DSC onset systematically occurred at a slightly lower temperature than that measured by DTT. This result, seen only for fresh tissue is in agreement with earlier experiments using hydrothermal isometric tension (HIT) testing. By contrast, DTT and DSC onset were identical for the exogenously crosslinked materials. Since the measured transition temperature was independent of initial load, this variable may be chosen to yield sharper force-temperature transitions with a given sample geometry. This instrument allows accurate assessment of collagen denaturation temperatures for multiple samples in a fraction of the time required by other methods.