title: The structural analysis of three-dimensional fibrous collagen hydrogels by Raman microspectroscopy.
abstract: To investigate molecular effects of 1-Ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC), EDC/N-hydroxysuccinimide (NHS), glyceraldehyde cross-linking as well as polymerization temperature and concentration on the three-dimensional (3D) collagen hydrogels, we analyzed the structures in situ by Raman microspectroscopy. The increased intensity of the 814 and 936 cm(-1) Raman bands corresponding to the C-C stretch of a protein backbone and a shift in the amide III bands from 1241 cm(-1)/1268 cm(-1) in controls to 1247 cm(-1)/1283 cm(-1) in glyceraldehyde-treated gels indicated changes to the alignment of the collagen molecules, fibrils/fibers and/or changes to the secondary structure on glyceraldehyde treatment. The increased intensity of 1450 cm(-1) band and the appearance of a strong peak at 1468 cm(-1) reflected a change in the motion of lysine/arginine CH2 groups. For the EDC-treated collagen hydrogels, the increased intensity of 823 cm(-1) peak corresponding to the C-C stretch of the protein backbone indicated that EDC also changed the packing of collagen molecules. The 23% decrease in the ratio of 1238 cm(-1) to 1271 cm(-1) amide III band intensities in the EDC-modified samples compared with the controls indicated changes to the alignment of the collagen molecules/fibrils and/or the secondary structure. A change in the motion of lysine/arginine CH2 groups was detected as well. The addition of NHS did not induce additional Raman shifts compared to the effect of EDC alone with the exception of a 1416 cm(-1) band corresponding to a COO(-) stretch. Overall, the Raman spectra suggest that glyceraldehyde affects the collagen states within 3D hydrogels to a greater extent compared to EDC and the effects of temperature and concentration are minimal and/or not detectable.
authors.affiliation: Cell Molecular and Developmental Biology Program, University of California, Riverside, CA, 92521.
authors.forename: Yu Jer
authors.initials: YJ
authors.lastname: Hwang
authors.forename: Julia G
authors.initials: JG
authors.lastname: Lyubovitsky
mesh_terms: D003094:Collagen / Q000737:chemistry; D005109:Extracellular Matrix; D020100:Hydrogels; D017433:Protein Structure, Secondary; D013059:Spectrum Analysis, Raman; D013696:Temperature
chemical_list: D020100:Hydrogels; D003094:Collagen