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

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pH5.5的缓冲溶液中,该薄膜电极在-0.25V(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(Ⅲ)/Fe(Ⅱ)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pH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(Ⅲ)/Fe(Ⅱ)电对的式量电位在pH4.5～11.0范围内与溶液pH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薄膜可以用于催化还原溶解氧和三氯乙酸.

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

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.