Sato Katsuhiko, Kodama Daisuke, Naka Yukihisa, Anzai Jun-ichi
Graduate School of Pharmaceutical Sciences, Tohoku University, Aramaki, Sendai 980-8578, Japan.
Biomacromolecules. 2006 Dec;7(12):3302-5. doi: 10.1021/bm060819q.
A layer-by-layer assembly composed of avidin and 2-iminobiotin-labeled poly(ethyleneimine) (ib-PEI) was prepared on the surface of a platinum (Pt) film-coated quartz resonator, and an electrochemically induced disintegration of the avidin-ib-PEI assembly was studied using a quartz crystal microbalance. The resonance frequency of a five-bilayer (avidin-ib-PEI)5 film-coated quartz resonator was increased upon application of an electric potential to the Pt layer of the quartz resonator, suggesting that the mass on the quartz resonator was decreased as a result of disintegration of the (avidin-ib-PEI)5 film, due to a pH change in the vicinity of the surface of the Pt-coated quartz resonator. It may be that the (avidin-ib-PEI)5 film assembly was decomposed by acidification of the local pH on the surface of the Pt layer, which in turn was induced through electrolysis of water on Pt, because ib-PEI forms complexes with avidin only in basic media. In pH 9 solution, the (avidin-ib-PEI)5 film was decomposed under the influence of an applied potential of 0.6-1.0 V versus Ag/AgCl. The (avidin-ib-PEI)5 film was decomposed almost completely within a minute in a low concentration buffer (1 mM, pH 9), while the decomposition was slower in 10 and 100 mM buffer solutions at the same pH. The decomposition of the assembly was rapid when the electrode potential was applied in pH 9 solutions, while the response was relatively slow in pH 10 and 11 solutions. All the results are rationalized on the basis of an electrochemically induced acidification of the local environment around the (avidin-ib-PEI)5 film on the Pt layer.
在涂有铂（Pt）薄膜的石英谐振器表面制备了由抗生物素蛋白和2-亚氨基生物素标记的聚（乙烯亚胺）（ib-PEI）组成的逐层组装体，并使用石英晶体微天平研究了抗生物素蛋白-ib-PEI组装体的电化学诱导分解。当向石英谐振器的Pt层施加电势时，涂有五层（抗生物素蛋白-ib-PEI）5薄膜的石英谐振器的共振频率增加，这表明由于涂有Pt的石英谐振器表面附近的pH变化，（抗生物素蛋白-ib-PEI）5薄膜分解导致石英谐振器上的质量减少。可能是（抗生物素蛋白-ib-PEI）5薄膜组装体因Pt层表面局部pH酸化而分解，而这又是通过Pt上的水电解诱导的，因为ib-PEI仅在碱性介质中与抗生物素蛋白形成复合物。在pH 9溶液中，相对于Ag/AgCl，在0.6 - 1.0 V的施加电势影响下，（抗生物素蛋白-ib-PEI）5薄膜分解。在低浓度缓冲液（1 mM，pH 9）中，（抗生物素蛋白-ib-PEI）5薄膜在一分钟内几乎完全分解，而同pH下在10 mM和100 mM缓冲溶液中分解较慢。当在pH 9溶液中施加电极电势时，组装体的分解很快，而在pH 10和11溶液中的响应相对较慢。所有结果都基于Pt层上（抗生物素蛋白-ib-PEI）5薄膜周围局部环境的电化学诱导酸化得到合理解释。
