Interaction study in homogeneous collagen/chondroitin sulfate blends by two-dimensional infrared spectroscopy

The neutral homogeneous collagen/chondroitin sulfate (Col/CS) blends were prepared when using 0.25 mol/LNaCl to stabilize the blends. Composition-dependent Fourier transform-infrared (FTIR) spectra were analyzed by generalized two-dimensional (2D) correlation spectroscopy to investigate the conformational changes of collagen and the specific interactions between collagen and CS. When adding CS to the collagen solution, C-H bending vibration of collagen varies firstly, then collagen skeleton, and finally the specific interactions between collagen and CS. The Col/CS ratios influence the kinds of specific interactions. Only hydroxyl groups of CS interact with C=O group of collagen owing to the charge shielding effect of NaCl when the CS content is less than 50 wt%. Besides hydrogen bond, the electrostatic interactions between ionized carboxyl group or sulfate group of CS and E-amino group of lysine or guanidine group of arginine appear when the CS content is more than 50 wt%. (C) 2012 Elsevier Ltd. All rights reserved.