Shen Li, Hu Naifei
Department of Chemistry, Beijing Normal University, Beijing 100875, China.
Biomacromolecules. 2005 May-Jun;6(3):1475-83. doi: 10.1021/bm049248x.
A novel thin film of heme proteins, including hemoglobin (Hb), myoglobin (Mb), and catalase (Cat), was successfully assembled layer by layer with polyamidoamine (PAMAM) dendrimers on different solid surfaces. At pH 7.0, protonated PAMAM possesses positive surface charges, whereas the proteins have net negative surface charges at pH above their isoelectric points. Thus, layer-by-layer {PAMAM/protein}(n)() films were assembled with alternate adsorption of oppositely charged PAMAM and proteins from their aqueous solutions mainly by electrostatic interaction. The assembly process was monitored by quartz crystal microbalance (QCM), UV-vis spectroscopy, and cyclic voltammetry (CV). The growth of the protein multilayer films was regular and linear, whereas the electroactivity of the films was only extended to a few bilayers. CVs of {PAMAM/protein}(n)() films showed a pair of well-defined and nearly reversible peaks characteristic of the protein heme Fe(III)/Fe(II) redox couples. Although {PAMAM/Hb}(n)() and {PAMAM/Mb}(n)() films showed very similar properties, {PAMAM/Cat}(n)() films displayed different and unique characters. The substrates with biological or environmental significance, such as oxygen, hydrogen peroxide, trichloroacetic acid, and nitrite, were catalytically reduced at {PAMAM/protein}(n)() film electrodes, showing the potential applicability of the films as new types of biosensors or bioreactors based on direct electrochemistry of the proteins. Both the electrochemical and electrocatalytic activity of {PAMAM/protein}(n)() films can be tailored precisely by controlling the number of bilayers or the film thickness.
一种包含血红蛋白（Hb）、肌红蛋白（Mb）和过氧化氢酶（Cat）的新型血红素蛋白质薄膜，通过聚酰胺胺（PAMAM）树枝状大分子在不同固体表面上成功地逐层组装而成。在pH 7.0时，质子化的PAMAM具有正表面电荷，而蛋白质在pH高于其等电点时具有净负表面电荷。因此，主要通过静电相互作用，从其水溶液中交替吸附带相反电荷的PAMAM和蛋白质，组装了逐层{PAMAM/蛋白质}(n)()薄膜。组装过程通过石英晶体微天平（QCM）、紫外可见光谱和循环伏安法（CV）进行监测。蛋白质多层膜的生长是规则且线性的，而膜的电活性仅扩展到少数几个双层。{PAMAM/蛋白质}(n)()膜的循环伏安图显示出一对明确且近乎可逆的峰，这是蛋白质血红素Fe(III)/Fe(II)氧化还原对的特征。尽管{PAMAM/Hb}(n)()和{PAMAM/Mb}(n)()膜表现出非常相似的性质，但{PAMAM/Cat}(n)()膜表现出不同且独特的特性。具有生物或环境意义的底物，如氧气、过氧化氢、三氯乙酸和亚硝酸盐，在{PAMAM/蛋白质}(n)()膜电极上被催化还原，这表明这些膜作为基于蛋白质直接电化学的新型生物传感器或生物反应器具有潜在的适用性。通过控制双层的数量或膜的厚度，可以精确调整{PAMAM/蛋白质}(n)()膜的电化学和电催化活性。
