Chemical Information Conversion System by Using Hydrogel-Modified Ultramicroelectrodes

水凝胶，如聚（N-异丙基丙烯酰胺）和聚丙烯酰胺，已成功地修饰到铂超微电极表面。通过在电极表面引入乙烯基，然后在电极表面合成凝胶，建立了化学修饰。这些凝胶修饰电极，其中凝胶的形状是半球形的溶胀状态，浸渍在含有氧化还原分子的水溶液中，并进行电化学测量。电极表面上凝胶的化学改性允许在凝胶的溶胀和收缩状态下以及进一步在溶胀的过渡状态下进行电化学测量，即，从膨胀状态到收缩状态，反之亦然。利用电化学方法，在平衡态和反相态下，分别测定了凝胶中氧化还原分子的浓度和扩散系数。 关于我们 肿胀的暂时状态。这为研究水凝胶的微环境和动力学提供了一种新的方法，同时，将水凝胶的大的溶胀变化，包括体积-相转变，转化为电信号。（N-异丙基丙烯酰胺）（PNIPAAm）凝胶，达到平衡溶胀，氧化还原分子[Ru（NH_3）_6]Cl_3，在溶胀状态下，凝胶与外部溶液的凝胶没有太大的不同，而在收缩的凝胶中发现了相当大的凝聚和复合物扩散率的抑制。对于聚丙烯酰胺（PAAm）凝胶，通过使用N-二茂铁基甲基-N，N，N-三甲基六氟磷酸铵（Fc）作为氧化还原分子，不仅在平衡状态下而且在溶胀的瞬时状态下进行测量。在收缩过程中测量的瞬时电解电流-时间（i-t）曲线，其中凝胶从水中浸入丙酮中，揭示了以下事实：1）i-t曲线在某一时刻出现峰值，而不是简单的下降; 2）在水溶液中，较小粒径的凝胶比较大粒径的凝胶出现峰值的时间早，且峰值时间与凝胶半径的平方成正比; 3）在水溶液中，峰电流随凝胶半径的减小而增大。考虑到收缩过程中凝胶的动力学和空间不均匀性。少

Hydrogels, such as poly(N-isopropyl acrylamide) and polyacrylamide, have been successfully moified onto the surface of Pt ultramicroelectrodes. The chemical modification has been established by the introduction of vinyl group onto the electrode surface, followed by the synthesis of the gels on the electrode surface. These gel-modified electrodes, where the shape of the gel is hemispherical in the swollen state, were immersed in aqueous solutions containing redox molecules, and electrochemical measurements were conducted. The chemical modification of the gels on the electrode surface allowed to conduct electrochemical measurements both in the swollen and shrunken states of the gels, and further in the transition states of swelling, i.e., from the swollen to shrunken states and vice versa. Independent determination of of the concentration and diffusion coefficient of the redox molecules inside the gels has been achieved by exploiting electrochemical methods both in equilibrated and trans … More ient state of swelling. This provides a new methodology to study micro-environment and dynamics of hydrogels, and at the same time, to convert large swelling change of hydrogels, including the volume-phase transition, to electric signal.In poly(N-isopropyl acrylamide)(PNIPAAm) gels, reaching equilibrated swelling, the concentration and diffusivity of redox molecule, [Ru(NH_3)_6]Cl_3, indide the gels were not so different from those of the outside solution in the swollen state, whereas considerable condensation and suppression in the diffusivity of the complex were found in the shrunken gels.For polyacrylamide(PAAm) gels, the measurements not only in the equilibrated state but also in the transient state of swelling were conducted by using N-ferrocenylmethyl-N, N, N-trimethylammonium hexafluorophosphate (Fc) as a redox molecule. The transient electrolytic current vs time(i-t) curves measured in the shrinking process, where the gel was immersed into acetone from water, revealed the following facts :1) The i-t curve showed a peak at a certain time, instead of simple decreasing.2) A smaller size gel showed the peak at earlier time than a larger size gel, and the peak time was directly proportional to the square of the radius of the gel in water.3) The peak current increased with decreasing the radius of the gel in water.Mechanism for these results has been analyzed, taking into consideration the dynamics and spatial inhomogeneity of the gels in the shrinking process. Less