Raman spectroscopic study of glutaraldehyde-stabilized collagen and pericardium tissue

For the first time, Raman spectroscopy has been employed to investigate formation of cross-links in collagen and porcine pericardium tissue upon glutaraldehyde (GA) treatment. GA treatment causes a very high fluorescence background, which overlaps Raman bands. It has been found that short fixation time, i.e. 2 h, reduces background radiation significantly, providing new possibilities for studying changes in molecular structure of collagen upon GA modification. The observed changes in position and intensity of Raman bands allowed us to recognize different types of GA-collagen interactions. Strong spectral evidence has been found for the peptide contribution to the formation of the GA-collagen cross-links and for the formation of secondary amines via Schiff base intermediates, and pyridinium-type cross-links. The results also revealed that different hydration levels and a more complex structure of intact tissue in comparison to collagen preparation strongly influence the formation of a GA cross-linking network, e.g. ether-type bond is preferred to form in a less hydrated collagen preparation. Our results have shown that GA treatment causes an increase in water content of pericardium tissue and collagen.