Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA.
Center for Neural Basis of Cognition, Pittsburgh, PA, USA.
J Mater Chem B. 2024 Jun 5;12(22):5535-5550. doi: 10.1039/d4tb00501e.
Invasive neural implants allow for high-resolution bidirectional communication with the nervous tissue and have demonstrated the ability to record neural activity, stimulate neurons, and sense neurochemical species with high spatial selectivity and resolution. However, upon implantation, they are exposed to a foreign body response which can disrupt the seamless integration of the device with the native tissue and lead to deterioration in device functionality for chronic implantation. Modifying the device surface by incorporating bioactive coatings has been a promising approach to camouflage the device and improve integration while maintaining device performance. In this work, we explored the novel application of a chondroitin sulfate (CS) based hydrophilic coating, with anti-fouling and neurite-growth promoting properties for neural recording electrodes. CS-coated samples exhibited significantly reduced protein-fouling which was maintained for up to 4-weeks. Cell culture studies revealed a significant increase in neurite attachment and outgrowth and a significant decrease in microglia attachment and activation for the CS group as compared to the control. After 1-week of implantation in the mouse cortex, the coated probes demonstrated significantly lower biofouling as compared to uncoated controls. Like the results, increased neuronal population (neuronal nuclei and neurofilament) and decreased microglial activation were observed. To assess the coating's effect on the recording performance of silicon microelectrodes, we implanted coated and uncoated electrodes in the mouse striatum for 1 week and performed impedance and recording measurements. We observed significantly lower impedance in the coated group, likely due to the increased wettability of the coated surface. The peak-to-peak amplitude and the noise floor levels were both lower in the CS group compared to the controls, which led to a comparable signal-to-noise ratio between the two groups. The overall single unit yield (% channels recording a single unit) was 74% for the CS and 67% for the control group on day 1. Taken together, this study demonstrates the effectiveness of the polysaccharide-based coating in reducing biofouling and improving biocompatibility for neural electrode devices.
侵入式神经植入物允许与神经组织进行高分辨率的双向通信，并已证明具有记录神经活动、刺激神经元以及以高空间选择性和分辨率感应神经化学物质的能力。然而，在植入后，它们会受到异物反应的影响，这可能会破坏设备与原生组织的无缝集成，并导致设备功能在慢性植入期间恶化。通过将生物活性涂层结合到设备表面来修饰设备已经成为一种有前途的方法，可以伪装设备并提高其集成度，同时保持设备性能。在这项工作中，我们探索了一种新型的基于硫酸软骨素 (CS) 的亲水性涂层的应用，该涂层具有抗污和促进神经突生长的特性，可用于神经记录电极。CS 涂层的样品表现出明显减少的蛋白质污染，这种情况可以维持长达 4 周。细胞培养研究表明，与对照组相比，CS 组的神经突附着和生长显著增加，而小胶质细胞附着和激活显著减少。在小鼠皮层植入 1 周后，与未涂层对照组相比，涂层探针的生物污染明显降低。与结果类似，观察到神经元群体（神经元核和神经丝）增加和小胶质细胞激活减少。为了评估涂层对硅微电极记录性能的影响，我们将涂层和未涂层电极植入小鼠纹状体 1 周，并进行阻抗和记录测量。我们观察到涂层组的阻抗明显降低，这可能是由于涂层表面的润湿性增加所致。与对照组相比，CS 组的峰峰值幅度和噪声基底水平都较低，这导致两组之间的信号噪声比相当。CS 组的单个单元产量（记录单个单元的通道百分比）在第 1 天为 74%，而对照组为 67%。总的来说，这项研究表明基于多糖的涂层在减少生物污染和提高神经电极设备的生物相容性方面是有效的。
