Study of the potential driven changes in a collagen film self-assembled on a polycrystalline gold electrode surface
Study of the potential driven changes in a collagen film self-assembled on a polycrystalline gold electrode surface
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DOI：
10.1016/j.jelechem.2013.08.010
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发表时间：
2013-10-01
影响因子：
4.5
通讯作者：
Brand, Izabella
中科院分区：
文献类型：
--
作者：
Ahlers, Michael;Stein, Nicolas;Brand, Izabella
采用电化学、原位椭圆偏振光谱和原位偏振调制红外反射吸收光谱研究了多晶金电极电位对胶原分子吸附状态和结构的影响。在宏观水平上，电位和相应的电荷积累在金电极上决定了胶原蛋白膜在Au电极表面的吸附过程。蛋白质膜在接近零电荷电势的电势下在电极表面上是稳定的。蛋白质膜维持大的负电位降（Δ phi（M垂直条S）>=-0.5V），而在膜上的小的正电位降（Δ phi（M垂直条S）近似于0.1V）下是不稳定的。在Au表面上积累的正净电荷引起带有正净电荷的胶原分子的静电排斥。水的松散和蛋白质膜的不稳定反映了Au电极和胶原分子之间的排斥。相反，在电荷密度为-8 <σ（M）< -20 μ C cm（-2）时，电极表面和蛋白质分子之间出现静电吸引。在Au表面形成稳定的、水合良好的胶原膜。在电极表面上积累的较高负电荷导致蛋白质膜被水溶胀并导致蛋白质膜从Au表面脱附。原位光谱电化学研究表明，在分子水平上，胶原分子的二级结构和取向都不受电势的影响。独立于作用在膜上的施加的电势和电场，胶原蛋白分子保持其天然结构。吸附在Au表面的胶原分子在分子水平上形成具有明确结构和不寻常稳定性的异质膜。(C)2013爱思唯尔有限公司版权所有。
The influence of the potential applied to the polycrystalline gold electrode on the adsorption state and structure of collagen molecules were studied by means of electrochemistry, in situ ellipsometry and in situ polarization modulation infrared reflection-absorption spectroscopy. At the macroscopic level, potential and the corresponding charge accumulated on the gold electrode determine the adsorption process of the collagen film on the Au electrode surface. The protein film is stable on the electrode surface at potentials close to the potential of zero charge. The protein film sustains a large negative potential drop (Delta phi(M vertical bar S) >= -0.5 V) whereas it is unstable at a small positive potential drop (Delta phi(M vertical bar S) approximate to 0.1 V) across the film. Positive net charge accumulated on the Au surface causes electrostatic repulsions of collagen molecules bearing a positive net charge. Loosening of water and destabilization of the protein film reflect repulsions between the Au electrode and the collagen molecules. In contrast, at charge densities between -8 < sigma(M) < -20 mu C cm(-2) electrostatic attractions between the electrode surface and the protein molecule appear. A stable, well hydrated collagen film is formed on the Au surface. Higher negative charges accumulated on the electrode surface lead to swelling on the protein film by water and lead to the desorption of the protein film from the Au surface. In situ spectroelectrochemical studies show that at the molecular level neither the secondary structure nor the orientation of collagen molecules are affected by electrical potentials. Independently of the applied potential and electric fields acting on the film the collagen molecule maintains its native structure. Collagen molecules adsorbed on the Au surface form a heterogeneous film with well-defined structure and unusual stability at the molecular level. (C) 2013 Elsevier B.V. All rights reserved.