Estimating Average Velocities of Particle Arrival Using the Time Duration of the Current Signal in Stochastic Blocking Electrochemistry.
Estimating Average Velocities of Particle Arrival Using the Time Duration of the Current Signal in Stochastic Blocking Electrochemistry.
复制标题
使用随机阻塞电化学中电流信号的持续时间估计粒子到达的平均速度。
DOI：
10.1021/acs.analchem.2c01201
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发表时间：
2022
影响因子：
7.4
通讯作者：
J. Álvarez
中科院分区：
文献类型：
--
作者：
Junaid U Ahmed;John A Lutkenhaus;Ashley Tubbs;A. Nag;J. Christopher;J. Álvarez
在随机阻断电化学中，微粒在微电极上吸附时会产生单独的电流步骤，并降低表面氧化还原介质反应的电流和通量。当前阶跃的振幅决定了粒子的大小和落点，而阶跃频率则与粒子的输运有关。在这里，我们报告了一种新的方法来估计单个杆状细菌（杆菌）的平均到达速度。该方法依赖于模拟离表面附近的阈值距离，在那里芽孢杆菌不再干扰介质通量并且当前步长接近于零。我们通过将阈值距离除以当前步骤持续时间来估计芽孢杆菌到达的平均速度，这是我们第一次检测到的参数，并且随着芽孢杆菌的长度而增加。通过比较扩散波动和芽孢杆菌的平均速度，我们估计扩散和迁移的贡献是细菌大小的函数。平均到达速度随芽孢杆菌长度的增加而增加，同时迁移增强，扩散减弱。我们的分析是通用的，在确定输运模式贡献方面比目前比较理论和实验阶跃频率的方法更有效。着陆位点的不确定性是无关紧要的，因为用于计算平均到达速度的步长已经包含了这些信息，并且不需要知道芽孢杆菌的电泳迁移率或ζ-势。此外，通过模拟并将边缘着陆分配给记录中当前步骤中重复次数最多的值，我们获得了与扫描电子显微镜相似的杆菌长度和宽度，从中我们推断着陆方向。
In stochastic blocking electrochemistry, microparticles generate individual current steps when they adsorb on a microelectrode and decrease the current and flux of a redox mediator reacting at the surface. The amplitude of the current step informs on particle size and landing locus, while step frequency correlates with particle transport. Here, we report a new method to estimate the average arrival velocities of single rod-shaped bacteria (bacilli). The method relies on simulating the nearby threshold distance from the surface where the bacillus no longer perturbs mediator flux and the current step approaches zero. We estimated the average velocities of bacillus arrival by dividing the threshold distance over the current step duration, a parameter that here we detect for the first time and increases with bacillus length. By comparing diffusional fluctuations to bacillus average velocity, we estimated diffusion and migration contributions as a function of bacterium size. Average arrival velocities increase with bacillus length at the same time as migration intensifies and diffusion weakens. Our analysis is universal and more effective in determining transport mode contributions than the present approach of comparing theoretical and experimental step frequencies. Uncertainty in landing locus is inconsequential because the step duration used to calculate the average arrival speed already contains such information and knowing bacillus electrophoretic mobility or ζ-potential is not needed. Additionally, by simulating and assigning edge landings to the most repeated values of current steps in a recording, we obtain bacilli lengths and widths similar to scanning electron microscopy, from which we infer landing orientation.