While fluorescence protein immobilized at the metal-solution interface has been known to exhibit voltage-dependent fluorescence, the underlying mechanism has remained unresolved. Here, we addressed the cathodic mechanism employing the characteristic properties of three different fluorescence proteins showing conventional pH-sensitivity, inverse pH-sensitivity, and green-to-red photo-convertibility. Through the analysis, we found that the interface-specific mode of protonation-deprotonation reactions underlies the cathodic effect, where the protonation state is directly coupled to hydrogen evolution at the interface rather than to the environmental acid-base equilibrium. The potential applications based on the interface effect are then discussed, including the spatially-resolved monitoring of hydrogen evolution reactions.

中文翻译：

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质子化-去质子化反应的界面特异性模式是荧光蛋白发射阴极调制的基础

虽然已知固定在金属-溶液界面的荧光蛋白会表现出电压依赖性荧光，但其潜在机制仍未得到解决。在这里，我们解决了采用三种不同荧光蛋白的特征特性的阴极机制，这些蛋白显示出传统的 pH 敏感性、反向 pH 敏感性和绿色到红色的光转换性。通过分析，我们发现质子化-去质子化反应的界面特定模式是阴极效应的基础，其中质子化状态与界面处的析氢直接耦合，而不是与环境酸碱平衡耦合。然后讨论了基于界面效应的潜在应用，包括析氢反应的空间分辨监测。