Department of Chemistry, McGill University, Montreal, Quebec H3A 0B8, Canada.
Department of Chemistry, University of Western Ontario, London, Ontario N6A 3K7, Canada.
Anal Chem. 2022 Oct 11;94(40):13852-13859. doi: 10.1021/acs.analchem.2c02498. Epub 2022 Sep 27.
Scanning electrochemical microscopy (SECM) has matured as a technique for studying local electrochemical processes. The feedback mode is most commonly used for extracting quantitative kinetic information. However, approaching individual regions of interest, as is commonly done, does not take full advantage of the spatial resolution that SECM has to offer. Moreover, fitting of experimental approach curves remains highly subjective due to the manner of estimating the tip-to-substrate distance. We address these issues using negative or positive feedback currents as a reference to calculate the tip-to-substrate distance directly for quantitative kinetic fitting of approach curves and line profiles. The method was first evaluated by fitting simulated data and then tested experimentally by resolving negative feedback and intermediate kinetics behavior in a spatially controlled fashion using (i) a flat, binary substrate composed of Au and SiO segments and (ii) a dual-mediator system for live-cell measurements. The methodology developed herein, named quantitative feedback referencing (QFR), improves fitting accuracy, removes fitting subjectivity, and avoids substrate-microelectrode contact.
扫描电化学显微镜（SECM）已经发展成为一种研究局部电化学过程的技术。反馈模式是最常用于提取定量动力学信息的方法。然而，像通常那样接近各个感兴趣的区域并没有充分利用 SECM 提供的空间分辨率。此外，由于估计尖端到基底距离的方式，实验接近曲线的拟合仍然非常主观。我们使用负反馈或正反馈电流作为参考，通过直接计算尖端到基底的距离，解决了这些问题，以便对接近曲线和线轮廓进行定量动力学拟合。该方法首先通过拟合模拟数据进行了评估，然后通过以下两种方式在实验中进行了测试：（i）使用由 Au 和 SiO 段组成的平面二元基底以空间控制的方式解决负反馈和中间动力学行为；（ii）使用双介体系统进行活细胞测量。本文提出的方法，命名为定量反馈参考（QFR），提高了拟合精度，消除了拟合主观性，并避免了基底-微电极接触。
