Mayner Eveline, Ronceray Nathan, Lihter Martina, Chen Tzu-Heng, Watanabe Kenji, Taniguchi Takashi, Radenovic Aleksandra
Laboratory of Nanoscale Biology, Institute of Bioengineering Ecole Polytechnique Federale de Lausanne, EPFL STI IBI-STI LBEN BM, Lausanne CH-1015, Switzerland.
Institute of Physics, Bijenicka 46, Zagreb HR-10000, Croatia.
ACS Nano. 2024 Oct 8;18(40):27401-27410. doi: 10.1021/acsnano.4c07189. Epub 2024 Sep 25.
Electrochemical techniques conventionally lack spatial resolution and average local information over an entire electrode. While advancements in spatial resolution have been made through scanning probe methods, monitoring dynamics over large areas is still challenging, and it would be beneficial to be able to decouple the probe from the electrode itself. In this work, we leverage single molecule microscopy to spatiotemporally monitor analyte surface concentrations over a wide area using unmodified hexagonal boron nitride (hBN) in organic solvents. Through a sensing scheme based on redox-active species interactions with fluorescent emitters at the surface of hBN, we observe a region of a linear decrease in the number of emitters against increasingly positive potentials applied to a nearby electrode. We find consistent trends in electrode reaction kinetics vs overpotentials between potentiostat-reported currents and optically read emitter dynamics, showing Tafel slopes greater than 290 mV·decade. Finally, we draw on the capabilities of spectral single-molecule localization microscopy (SMLM) to monitor the fluorescent species' identity, enabling multiplexed readout. Overall, we show dynamic measurements of analyte concentration gradients on a micrometer-length scale with nanometer-scale depth and precision. Considering the many scalable options for engineering fluorescent emitters with two-dimensional (2D) materials, our method holds promise for optically detecting a range of interacting species with exceptional localization precision.
传统的电化学技术缺乏空间分辨率，并且会对整个电极上的局部信息进行平均。虽然通过扫描探针方法在空间分辨率方面取得了进展，但在大面积上监测动力学仍然具有挑战性，并且能够将探针与电极本身分离将是有益的。在这项工作中，我们利用单分子显微镜在有机溶剂中使用未修饰的六方氮化硼（hBN）在宽区域内时空监测分析物的表面浓度。通过基于氧化还原活性物质与hBN表面荧光发射体相互作用的传感方案，我们观察到随着施加到附近电极的电位越来越正，发射体数量呈线性下降的区域。我们发现在恒电位仪报告的电流与光学读取的发射体动力学之间，电极反应动力学与过电位之间存在一致的趋势，显示塔菲尔斜率大于290 mV·decade。最后，我们利用光谱单分子定位显微镜（SMLM）的能力来监测荧光物质的身份，实现多路读出。总体而言，我们展示了在微米长度尺度上对分析物浓度梯度进行具有纳米尺度深度和精度的动态测量。考虑到用二维（2D）材料设计荧光发射体的许多可扩展选项，我们的方法有望以出色的定位精度光学检测一系列相互作用的物种。
