Large-scale inhomogeneous plasmonic metal chips have been demonstrated as a promising platform for biochemical sensing, but the origin of their strong fluorescence enhancements and average gap dependence is a challenging issue due to the complexity of modeling tremendous molecules within inhomogeneous gaps. To address this issue, we bridged microscopic mechanisms and macroscopic observations, developed a kinetic model, and experimentally investigated the fluorescence enhancement factors of IR800-streptavidin immobilized on metal nanoisland films (NIFs). Inspired by the kinetic model, we controlled the distribution of IR800-streptavidin within the valleys of NIFs by regioselective modification and achieved the fluorescence intensity enhancement up to 488-fold. The kinetic model allows us to qualitatively explain the mechanism of fluorescence intensity enhancements and quantitatively predict the trend of experimental enhancement factors, thereby determining the design principles of the plasmonic metal chips. Our study provides one key step further toward the sensing applications of large-scale plasmonic metal chips.

大规模不均匀等离激元金属芯片已被证明是一种有前途的生化传感平台，但由于在不均匀间隙中对巨大分子进行建模的复杂性，其强大的荧光增强和平均间隙依赖性的起源是一个具有挑战性的问题。为了解决这个问题，我们架起了微观机制和宏观观察的桥梁，建立了动力学模型，并实验研究了固定在金属纳米岛膜（NIF）上的IR800-链霉亲和素的荧光增强因子。受到动力学模型的启发，我们通过区域选择性修饰来控制IR800-链霉亲和素在NIF谷中的分布，并实现了高达488倍的荧光强度增强。动力学模型使我们能够定性地解释荧光强度增强的机理，并定量预测实验性增强因子的趋势，从而确定等离子体金属芯片的设计原理。我们的研究为大规模等离子金属芯片的传感应用提供了进一步的关键一步。