基于二维红外技术研究氧化羧甲基纤维素钠/胶原的相互作用及热稳定性

采用氧化羧甲基纤维素钠(OCMC)作为交联剂,对胶原溶液进行改性并采用二维红外技术分析OCMC与胶原之间的相互作用及其对胶原热稳定性的影响.一维红外图谱显示OCMC交联改性对胶原的主要特征吸收峰即酰胺Ⅰ,Ⅱ和Ⅲ带的峰位与强度无明显影响;改性前后胶原的酰胺Ⅲ带与1455 cm-1处吸光度的比值AⅢ/A1455均接近于1....

Interaction and Thermal Stability of Oxidized Carboxymethyl Cellulose/Collagen Based on Two-Dimensional Infrared Spectroscopy

Collagen was modified by oxidized carboxymethyl cellulose (OCMC) and then their interaction and thermal stability were investigated by two-dimensional infrared spectroscopy (2D-IR). One-dimensional infrared spectra showed that the positions and intensities of the main characteristic absorption peaks (amide Ⅰ, Ⅱ and Ⅲ bands) for collagen had no significant change upon cross-linking; additionally, all the absorption ratios of amide Ⅲ bands to 1 455 cm-1 (A_Ⅲ/A_{1 455}) of native and cross-linking collagen were close to 1.000. These results indicated that the triple helix of collagen was not demolished by the introduction of cross-linking. The 2D-IR spectra were constructed from OCMC amount-dependent infrared spectra, and then the interaction between OCMC and collagen was further analyzed. The response sensitivity and order of collagen structure and the groups of OCMC showed that electrostatic interaction formed firstly between carboxyl groups of OCMC and guanidine or amino groups of collagen. Then Schiff’s base reaction occurred between aldehyde groups of OCMC and amino groups of collagen, which was the dominated interaction. As a result, the thermal stability of cross-linked collagen increased. With the increase of temperature, the red-shift of absorption bands and the decreased A_Ⅲ/A_{1 455} value reflected that hydrogen bonds were weakened, and the unwinding of triple helix occurred for both native and cross-linked collagens; whereas the fewer changes in red-shift and A_Ⅲ/A_{1 455} value for cross-linked collagen also confirmed the increase in thermal stability. Furthermore, the 2D-IR spectra were constructed from the temperature-dependent infrared spectra and provided information about the thermally induced structural changes. It could be conjectured that the triple helix was transformed into random coils for the native and cross-linked collagen, resulting in the loss of secondary structure with increasing the temperature. Nevertheless, the response sensitivity and order of the triple helix to temperature changed significantly. (1) For native collagen, the most temperature-sensitive structure was triple helix; whereas, it was random coils for cross-linked collagen, demonstrating that the triple helix of cross-linked collagen was less sensitive to temperature than that of native collagen. (2) Moreover, the response order of the triple helix for cross-linked collagen to the increased temperature lagged. It was illustrated that the stabilization of collagen by OCMC was due to the reinforcement of the triple helix.