Geng Rong, Zhao Guohua, Liu Meichuan, Li Mingfang
Department of Chemistry, Tongji University, 1239 Siping Road, Shanghai 200092, People's Republic of China.
Biomaterials. 2008 Jun;29(18):2794-801. doi: 10.1016/j.biomaterials.2008.03.004. Epub 2008 Apr 3.
A novel sandwich structured SiO(2) gel/cytochrome c (Cyt c)/SiO(2) gel was designed and constructed on conductive boron-doped diamond (BDD) film substrate. A SiO(2) gel membrane was first in situ deposited on the pretreated positive charged H-terminated BDD electrode with a simple and artful surface vapor sol-gel method. Cyt c was subsequently immobilized onto the SiO(2) membranes by electrostatic attraction, followed by another SiO(2) gel layer in situ depositing on it. The SiO(2) interlayer was conceived to play an important role in the resultant sandwich structured SiO(2)/Cyt c/SiO(2)/BDD electrode as a selective "semi-open" medium, which guaranteed the immobilized Cyt c to maintain high stability and perform good electrochemistry and biocatalysis responses. The bioactivity of Cyt c was well protected and the immobilized biomolecule even didn't denature at extremely high or low pH condition. More attractively, Cyt c in the sandwich structured electrode could be further oxidized into highly reactive Cyt c pi-cation by two-step electrochemical oxidation, which could oxidize NO(2)(-) into NO(3)(-) in the solution. A sensitive determination approach of nitrite was accordingly built up based on this biocatalytic oxidative interaction for the first time and a possible mechanism of the interaction was herein proposed.
一种新型的三明治结构二氧化硅凝胶/细胞色素c（Cyt c）/二氧化硅凝胶在导电硼掺杂金刚石（BDD）薄膜基底上被设计并构建出来。首先，通过一种简单巧妙的表面气相溶胶-凝胶法，在经过预处理的带正电荷的氢端终止BDD电极上原位沉积一层二氧化硅凝胶膜。随后，细胞色素c通过静电吸引固定在二氧化硅膜上，接着再在其上原位沉积另一层二氧化硅凝胶层。二氧化硅中间层在所得的三明治结构二氧化硅/细胞色素c/二氧化硅/BDD电极中被认为起着重要作用，作为一种选择性的“半开放”介质，它保证了固定化的细胞色素c保持高稳定性，并表现出良好的电化学和生物催化响应。细胞色素c的生物活性得到了很好的保护，并且固定化的生物分子在极高或极低的pH条件下甚至都不会变性。更吸引人的是，三明治结构电极中的细胞色素c可以通过两步电化学氧化进一步氧化成高活性的细胞色素c π-阳离子，它可以将溶液中的亚硝酸根离子（NO₂⁻）氧化成硝酸根离子（NO₃⁻）。基于这种生物催化氧化相互作用，首次建立了一种灵敏的亚硝酸盐测定方法，并在此提出了一种可能的相互作用机制。
