Biomimetic Approach to Confer Redox Activity to Thin Chitosan Films
Biomimetic Approach to Confer Redox Activity to Thin Chitosan Films
复制标题
DOI：
10.1002/adfm.200902428
复制
发表时间：
2010-08-23
影响因子：
19
通讯作者：
Payne, Gregory F.
中科院分区：
文献类型：
--
作者：
Kim, Eunkyoung;Liu, Yi;Payne, Gregory F.
生物体内的电子转移以单个电子或电子对的形式发生，并且常常由儿茶酚/邻醌氧化还原对介导。在此，通过两步制备了一种仿生多糖 - 儿茶酚膜。首先，将刺激响应性多糖壳聚糖电沉积为一种可渗透膜。接下来，将涂有壳聚糖的电极浸入含有儿茶酚的溶液中，并将电极偏压以对儿茶酚进行阳极氧化。电化学石英晶体微天平（EQCM）研究表明，氧化产物共价接枝到壳聚糖膜上。循环伏安法（CV）测量表明，儿茶酚修饰的壳聚糖膜具有氧化还原活性，尽管它们不导电且不能直接将电子转移到下面的电极。儿茶酚修饰的壳聚糖膜作为电子的局部源或汇，可将电子转移到可溶性介质（例如，二茂铁二甲醇和Ru(NH₃)₆Cl³⁻）。这种电子源/汇是有限的，可能会耗尽，但通过短暂（30秒）的电化学处理可反复再生。此外，儿茶酚修饰的壳聚糖膜能够：i）放大与可溶性介质相关的电流，ii）在氧化或还原方向上部分整流这些电流（取决于介质），以及iii）在再生 - 开启和耗尽 - 关闭状态之间切换。提出了物理模型来解释这些新的氧化还原特性，并讨论了可能来自自然界的先例。
Electron transfer in biology occurs with individual or pairs of electrons, and is often mediated by catechol/o-quinone redox couples. Here, a biomimetic polysaccharide-catecholic film is fabricated in two steps. First, the stimuli-responsive polysaccharide chitosan is electrodeposited as a permeable film. Next, the chitosan-coated electrode is immersed in a solution containing catechol and the electrode is biased to anodically-oxidize the catechol. The oxidation products covalently graft to the chitosan films as evidenced by electrochemical quartz crystal microbalance (EQCM) studies. Cyclic voltammetry (CV) measurements demonstrate that the catechol-modified chitosan films are redox-active although they are non-conducting and cannot directly transfer electrons to the underlying electrode. The catechol-modified chitosan films serve as a localized source or sink of electrons that can be transferred to soluble mediators (e.g., ferrocene dimethanol and Ru(NH3) Cl-6(3)). This electron source/sink is finite, can be depleted, but can be repeatedly regenerated by brief (30 s) electrochemical treatments. Further, the catechol-modified chitosan films can i) amplify currents associated with the soluble mediators, ii) partially-rectify these currents in either oxidative or reductive directions (depending on the mediator), and iii) switch between regenerated-ON and depleted-OFF states. Physical models are proposed to explain these novel redox properties and possible precedents from nature are discussed.