Ramesh Vaijayanthi, Rehbock Christoph, Giera Brian, Karnes John J, Forien Jean-Baptiste, Angelov Svilen D, Schwabe Kerstin, Krauss Joachim K, Barcikowski Stephan
Technical Chemistry I, Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, 45141 Essen, Germany.
Center for Engineered Materials and Manufacturing, Lawrence Livermore National Laboratory, Livermore, California 94550, United States.
Langmuir. 2021 Aug 6. doi: 10.1021/acs.langmuir.1c01081.
Electrophoretic deposition (EPD) of platinum nanoparticles (PtNPs) on platinum-iridium (Pt-Ir) neural electrode surfaces is a promising strategy to tune the impedance of electrodes implanted for deep brain stimulation in various neurological disorders such as advanced Parkinson's disease and dystonia. However, previous results are contradicting as impedance reduction was observed on flat samples while in three-dimensional (3D) structures, an increase in impedance was observed. Hence, defined correlations between coating properties and impedance are to date not fully understood. In this work, the influence of direct current (DC) and pulsed-DC electric fields on NP deposition is systematically compared and clear correlations between surface coating homogeneity and impedance are established. The ligand-free NPs were synthesized via pulsed laser processing in liquid, yielding monomodal particle size distributions, verified by analytical disk centrifugation (ADC). Deposits formed were quantified by UV-vis supernatant analysis and further characterized by scanning electron microscopy (SEM) with semiautomated interparticle distance analyses. Our findings reveal that pulsed-DC electric fields yield more ordered surface coatings with a lower abundance of particle assemblates, while DC fields produce coatings with more pronounced aggregation. Impedance measurements further highlight that impedance of the corresponding electrodes is significantly reduced in the case of more ordered coatings realized by pulsed-DC depositions. We attribute this phenomenon to the higher active surface area of the adsorbed NPs in homogeneous coatings and the reduced particle-electrode electrical contact in NP assemblates. These results provide insight for the efficient EPD of bare metal NPs on micron-sized surfaces for biomedical applications in neuroscience and correlate coating homogeneity with functionality.
在铂铱（Pt-Ir）神经电极表面电泳沉积铂纳米颗粒（PtNPs）是一种很有前景的策略，可用于调节植入电极的阻抗，这些电极用于治疗各种神经系统疾病，如晚期帕金森病和肌张力障碍的深部脑刺激。然而，先前的结果相互矛盾，因为在平面样品上观察到阻抗降低，而在三维（3D）结构中，观察到阻抗增加。因此，涂层性质与阻抗之间明确的相关性至今尚未完全理解。在这项工作中，系统地比较了直流（DC）电场和脉冲直流电场对纳米颗粒沉积的影响，并建立了表面涂层均匀性与阻抗之间的明确相关性。通过液体中的脉冲激光加工合成了无配体纳米颗粒，通过分析盘式离心法（ADC）验证了其单峰粒度分布。通过紫外可见上清液分析对形成的沉积物进行定量，并通过扫描电子显微镜（SEM）和半自动颗粒间距离分析进一步表征。我们的研究结果表明，脉冲直流电场产生的表面涂层更有序，颗粒聚集体的丰度更低，而直流电场产生的涂层聚集更明显。阻抗测量进一步突出显示，在通过脉冲直流沉积实现更有序涂层的情况下，相应电极的阻抗显著降低。我们将这种现象归因于均匀涂层中吸附纳米颗粒的活性表面积更高，以及纳米颗粒聚集体中颗粒与电极的电接触减少。这些结果为裸金属纳米颗粒在微米级表面上的高效电泳沉积提供了见解，用于神经科学中的生物医学应用，并将涂层均匀性与功能联系起来。
