Hengge Elisabeth, Steyskal Eva-Maria, Bachler Rupert, Dennig Alexander, Nidetzky Bernd, Würschum Roland
Insitute of Materials Physics, Graz University of Technology, Petersgasse 16, A-8010 Graz, Austria.
Institute of Biotechnology and Biochemical Engineering, Graz University of Technology, Petersgasse 12, A-8010 Graz, Austria.
Beilstein J Nanotechnol. 2019 Nov 18;10:2275-2279. doi: 10.3762/bjnano.10.219. eCollection 2019.
Surface modifications of nanoporous metals have become a highly attractive research field as they exhibit great potential for various applications, especially in biotechnology. Using self-assembled monolayers is one of the most promising approaches to modify a gold surface. However, only few techniques are capable of characterizing the formation of these monolayers on porous substrates. Here, we present a method to in situ monitor the adsorption and desorption of self-assembled monolayers on nanoporous gold by resistometry, using cysteine as example. During the adsorption an overall relative change in resistance of 18% is detected, which occurs in three distinct stages. First, the cysteine molecules are adsorbed on the outer surface. In the second stage, they are adsorbed on the internal surfaces and in the last stage the reordering accompanied by additional adsorption takes place. The successful binding of cysteine on the Au surface was confirmed by cyclic voltammetry, which showed a significant decrease of the double-layer capacitance. Also, the electrochemically controlled desorption of cysteine was monitored by concomitant in situ resistometry. From the desorption peak related to the (111) surface of the structure, which is associated with a resistance change of 4.8%, an initial surface coverage of 0.48 monolayers of cysteine could be estimated.
纳米多孔金属的表面改性已成为一个极具吸引力的研究领域，因为它们在各种应用中展现出巨大潜力，尤其是在生物技术领域。使用自组装单分子层是修饰金表面最有前景的方法之一。然而，只有少数技术能够表征这些单分子层在多孔基底上的形成情况。在此，我们以半胱氨酸为例，介绍一种通过电阻测量原位监测自组装单分子层在纳米多孔金上吸附和解吸的方法。在吸附过程中，检测到电阻的总体相对变化为18%，这一变化分三个不同阶段发生。首先，半胱氨酸分子吸附在外表面。在第二阶段，它们吸附在内表面，最后阶段发生伴随额外吸附的重新排列。通过循环伏安法证实了半胱氨酸在金表面的成功结合，该方法显示双层电容显著降低。此外，通过同步原位电阻测量监测了半胱氨酸的电化学控制解吸。从与结构的(111)表面相关的解吸峰（与4.8%的电阻变化相关）可以估计，半胱氨酸的初始表面覆盖率为0.48单层。
