肌红蛋白在双十二烷基二甲基溴化铵-粘土多双层复合薄膜电极上的电化学与电催化

Electrochemistry and Electrocatalysis with Myoglobin at DDAB-clay Multibilayer Composite Film Electrodes

将双十二烷基二甲基溴化铵 ( DDAB) -粘土 ( Clay)复合物的水分散系与肌红蛋白 ( Mb)水溶液的混合物涂布到热解石墨 ( PG)电极表面 ,可制得 Mb-DDAB-Clay薄膜电极 .在 p H5.5的缓冲溶液中 ,该薄膜电极在-0 .2 5V( vs.SCE)处有一对可逆的循环伏安还原氧化峰 ,为 Mb血红素辅基 Fe( ) /Fe( )电对的特征峰 .在 DDAB-Clay薄膜的微环境中 ,Mb与 PG电极之间的电子传递得到极大促进 ,并显示了很好的稳定性 .Soret吸收带的位置表明 ,在适中的 p H范围内 ,Mb在薄膜中保持了其原始构象 .X射线衍射实验结果表明 ,Mb的嵌入并未对薄膜的有序多层结构有很大影响 .在 DDAB-Clay薄膜环境中 ,Mb血红素 Fe( ) /Fe( )电对的式量电位在 p H4 .5～ 1 1 .0范围内与溶液 p H值成线性关系 ,表明 Mb的电化学还原很可能是一个质子伴随一个电子的电极过程 .

Mb DDAB clay film electrodes were made by casting aqueous dispersions of didodecyldimethylammonium bromide(DDAB) clay composite and the protein myoglobin(Mb) on pyrolytic graphite(PG) electrodes. Cyclic voltammetry of Mb DDAB clay films showed a pair of well defined and nearly reversible peaks at about -0.25 V vs. SCE in pH 5.5 buffers, being the characteristic peaks of the Mb heme Fe(Ⅲ)/Fe(Ⅱ) redox couples. In the microenvironment of DDAB clay films, the electron transfer between Mb and PG was greatly enhanced, and showed a good stability during storage. Soret absorption band positions suggested that Mb retained its native conformation in these films at medium pH. The interlayer clay spacing estimated by X ray diffraction suggested that the incorporated Mb did not disturb the ordered multilayer structure of the films. The average formal potential of Mb heme Fe(Ⅲ)/Fe(Ⅱ) couples in DDAB clay films shifted linearly from pH 4.5 to 11 with a slope of -53 mV/pH, suggesting that one proton was coupled with each electron transfer. The dissolved oxygen and trichloroacetic acid was catalytically reduced by Mb DDAB clay film electrodes.