明胶/Fe_2S_3纳米生物复合物形成反应的热力学及明胶构象变化  

The Thermodynamics of Gelatin/Fe_2S_3 Bionanocomposites Formation and Gelatin Conformational Change

作　　者：王白杨[1] 肖新光[1] 唐世华[1] 刘岑[1] 

机构地区：[1]广西民族大学化学化工学院广西林产化学与工程重点实验室,广西南宁530007

出　　处：《影像科学与光化学》2014年第6期505-513,共9页Imaging Science and Photochemistry

基　　金：国家自然科学基金(21067001);广西民族大学研究生教育创新计划(gxun-chx2012091)资助

摘　　要：在pH=7.40条件下,采用一锅化学反应法制得水溶性明胶/Fe2S3纳米生物复合物,扫描电镜照片显示Fe2S3颗粒为棒状。根据吸光度与Fe2S3浓度关系,由Benesi-Hildebrand方程计算了不同温度下反应的形成常数K(293K:14.47×102L·mol-1;297K:9.24×102 L·mol-1;309K:1.70×102L·mol-1)及对应温度下反应的热力学参数(ΔrGm=-17.88/-16.68/-13.09kJ·mol-1;ΔrHm=-105.57kJ·mol-1;ΔrSm=-299.28J·K-1·mol-1),结果表明明胶/Fe2S3纳米生物复合物的形成反应是自发的放热过程,且为焓驱动。傅里叶变换红外光谱表明,Fe2S3主要与明胶大分子肽链中的酰胺键结合;对红外光谱进行去卷积拟合,结果表明:明胶蛋白质的α-螺旋含量减少,β-折叠含量明显增加。结合紫外和红外光谱测试结果对复合物的形成机理作了初步的推测:首先Fe3+与明胶大分子中的酰胺键结合形成明胶/Fe3+复合物,然后S2-与明胶/Fe3+中的Fe3+形成明胶/Fe2S3复合物。The gelatin/Fe2 S3 bionanocomposite was synthesized via a facile one-pot chemical route at pH= 7.40. The SEM image showed that the shapes of the hionanocomposites were rod-like. Based on the relationship between the absorbance data of system and the concentration of Fe2 S3, the Benesi Hildebrand equation was used to calculate the formation constants K（293 K： 14.47 102 L · mol^-1 ; 297 K： 9.24 102L · tool-1 ; 309 K： 1.70 102L · mol 1） at three different temperatures. Thermodynamic parameters were also determined （△rGm = -17.88/-16.68/-13.09 kJ · mo1^-1 ; ArH,,,=--105.57 kJ · mol^-1; ArSm：-299. 28 J · K^-1 · mol^-1）. The results indicated the formation process was spontaneous, exothermic and enthalpy-driven. FT-IR data indicated that the amide linkage in gelatin polypeptide chain can he especially active sites for the nucleation and growth of Fe2S3. The effect of Fe^3＋ and Fe2 S3 on the conformations of gelatin macromolecule had also been analyzed by means of UV-vis and FT-IR spectra. The results showed that there was less α-helix content and more β-sheet structures due to integration of them. By integrating the information of the UV-vis and FT-IR analyses of the synthesized samples, a most plausible formation mechanism of the gelatin/Fe2S3 bionanocomposites was given： Fe^3＋ coordinated with amide linkage in gelatin macromolecule to form gelatin/Fe^3＋ complex, then S^2- combined with Fe^3＋ cooperated by gelatin to form gelatin/Fe2 S3.

关 键 词：明胶/Fe2S3纳米生物复合物 明胶 热力学参数 构象变化 

分 类 号：O642.1[理学—物理化学]