Luong J H, Brown R S, Schmidt P M
Biotechnology Research Institute, National Research Council Canada, Montreal.
J Mol Recognit. 1995 Jan-Apr;8(1-2):132-8. doi: 10.1002/jmr.300080123.
Inclusion complexes of 1,1'-dimethylferrocene (DMFe) with alpha-, 2-hydroxypropyl-beta- or gamma-cyclodextrins were formed in aqueous systems. For the first time, the interacting DMFe-cyclodextrin systems have been characterized using cyclic voltammetry which enabled the estimation of the complexation order, the formation constant and the diffusivity. Cyclic voltammetry was performed at a stationary electrode, yielding complexation ratios of 1:2 for DMFe with alpha-cyclodextrin and 1:1 with the other two cyclodextrins, as expected from the known cavity dimensions for the cyclodextrins. Formation constants of 4.4 x 10(4) M-2, 1.2 x 10(3) M-1 and 2.9 x 10(2) M-1 were then determined for the complexes between DMFe and the alpha-, beta- and gamma-cyclodextrins, respectively, in relative agreement with the literature. The maximum complexation efficiency, diffusivity and solubility were observed for the DMFe:2-hydroxypropyl-beta-cyclodextrin inclusion complex, which, combined with cost factors, resulted in the selection of this form for bioelectrocatalysis studies. The efficiency of the complex as a mediator for the glucose:glucose oxidase system was determined by measuring the rate constant (ks) for reaction of the oxidized DMFe with the reduced enzyme. The ks value decreased from 3.4 x 10(4) M-1 s-1 to 1.9 x 10(4) M-1 s-1 with an increase in 2-hydroxypropyl-beta-cyclodextrin concentration from 4 mM to 10 mM. In this range, the ks value is similar to that of free ferrocene, implying a high efficiency of the DMFe:2-hydroxypropyl-beta-cyclodextrin inclusion complex.
在水体系中形成了1,1'-二甲基二茂铁（DMFe）与α-、2-羟丙基-β-或γ-环糊精的包合物。首次使用循环伏安法对相互作用的DMFe-环糊精体系进行了表征，从而能够估算络合顺序、形成常数和扩散系数。在固定电极上进行循环伏安法测定，得到DMFe与α-环糊精的络合比为1:2，与另外两种环糊精的络合比为1:1，这与环糊精已知的空腔尺寸预期一致。然后分别测定了DMFe与α-、β-和γ-环糊精之间络合物的形成常数，分别为4.4×10⁴ M⁻²、1.2×10³ M⁻¹和2.9×10² M⁻¹，与文献相对一致。观察到DMFe:2-羟丙基-β-环糊精包合物具有最大的络合效率、扩散系数和溶解度，结合成本因素，选择这种形式用于生物电催化研究。通过测量氧化态DMFe与还原态酶反应的速率常数（ks）来确定该络合物作为葡萄糖:葡萄糖氧化酶体系介质的效率。随着2-羟丙基-β-环糊精浓度从4 mM增加到10 mM，ks值从3.4×10⁴ M⁻¹ s⁻¹降至1.9×10⁴ M⁻¹ s⁻¹。在此范围内，ks值与游离二茂铁的相似，这意味着DMFe:2-羟丙基-β-环糊精包合物具有较高的效率。
