Different synthesis methods allow to tune the permeability and permselectivity of dopamine-melanin films to electrochemical probes
Different synthesis methods allow to tune the permeability and permselectivity of dopamine-melanin films to electrochemical probes
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DOI：
10.1016/j.electacta.2011.02.028
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发表时间：
2011-04-15
影响因子：
6.6
通讯作者：
Ball, Vincent
中科院分区：
文献类型：
--
作者：
Bernsmann, Falk;Voegel, Jean-Claude;Ball, Vincent
通过多巴胺氧化制备黑色素膜的不同方法比较了它们对中性或携带正电荷或负电荷的电化学探针的渗透性。为了检查电荷依赖性的渗透性不同的电荷探针类似的大小（六胺钌，二茂铁甲醇和hexacyanoferrate）。我们故意不调查的渗透性的金属阳离子通过黑色素膜，由于其可能的络合物的儿茶酚基团的黑色素。通过溶液氧化方法（O-2或Cu 2+作为氧化剂）制备的膜在其厚度达到5-10 nm时对六氰基高铁酸盐是不可渗透的，但在变得不可渗透之前对六胺钌和二茂铁甲醇保持可渗透，直到厚度达到25-40 nm。通过电化学沉积制备的黑色素膜显示出显着的差异：它们保持可渗透的hexacyanoferrate高达35 nm的厚度和六胺钌和二茂铁甲醇的最大厚度，可以通过这种沉积方法达到。当达到45 nm的最大膜厚度时，膜也变得对这两种氧化还原探针不可渗透。这些结果的基础上解释的黑色素膜的分子水平上的结构差异。黑色素涂层的选择透过性与其在7.5的工作pH下的负表面电荷密度有关。(C)2011爱思唯尔有限公司保留所有权利。
Different methods to prepare melanin films by dopamine oxidation are compared with respect to their permeability to electrochemical probes being either neutral or carrying a positive or a negative charge. To examine charge-dependence of the permeability differently charged probes of similar size (hexaamineruthenium, ferrocenemethanol and hexacyanoferrate) are employed. We deliberately not investigated the permeability of metal cations through the melanin films owing to their possible complexation by the catechol groups of melanin. The films prepared by solution oxydation methods (O-2 or Cu2+ as oxidants) are impermeable to hexacyanoferrate as soon as their thickness reaches 5-10 nm but remain permeable to hexaamineruthenium and ferrocenemethanol up to thickness reaching 25-40 nm before becoming also impermeable. The melanin films prepared by electrochemical deposition display a marked difference: they remain permeable to hexacyanoferrate up to 35 nm in thickness and to hexaamineruthenium and ferrocenemethanol up to the maximal thickness that can be reached by this deposition method. When the maximal film thickness of 45 nm is reached the film becomes also impermeable to these two redox probes. These results are explained on the basis of structural differences of the melanin films at the molecular level. The permselectivity of the melanin coatings is related to their negative surface charge density at the working pH of 7.5. (C) 2011 Elsevier Ltd. All rights reserved.