用于神经刺激的改良聚（3,4-乙撑二氧噻吩）（PEDOT）。
Improved Poly(3,4-Ethylenedioxythiophene) (PEDOT) for Neural Stimulation.
作者信息
Mandal Himadri Shekhar, Kastee Jemika Shrestha, McHail Daniel Glenn, Rubinson Judith Faye, Pancrazio Joseph Jewell, Dumas Theodore Constantine
机构信息
Department of Bioengineering, George Mason University, Fairfax, VA, USA.
Department of Molecular Neuroscience, The Krasnow Institute for Advanced Study, George Mason University, Fairfax, VA, USA.
出版信息
Neuromodulation. 2015 Dec;18(8):657-63. doi: 10.1111/ner.12285. Epub 2015 Mar 21.
OBJECTIVE
This study compares the stability of three variations of the conductive polymer poly(3,4-ethylenedioxythiophene) or PEDOT for neural micro-stimulation under both in vitro and in vivo conditions. We examined PEDOT films deposited with counter-ions tetrafluoroborate (TFB) and poly(styrenesulfonate) (PSS), and
PEDOT
PSS combined with carbon nanotubes (CNTs).
METHODS
For the in vitro stability evaluation, implantable micro-wires were coated with the polymers, placed in a vial containing phosphate buffered saline (PBS) under accelerated aging conditions (60°C), and current pulses were applied. The resulting voltage profile was monitored over time. Following the same polymer deposition protocol, chronic neural micro-probes were modified and implanted in the motor cortex of two rats for the in vivo stability comparison. Similar stimulating current pulses were applied and the output voltage was examined. The electrochemical impedance spectroscopic (EIS) data were also recorded and fit to an equivalent circuit model that incorporates and quantifies the time-dependent polymer degradation and impedance associated with tissue surrounding each micro-electrode site.
RESULTS
Both in vitro and in vivo voltage output profiles show relatively stable behavior for the
PEDOT
TFB modified micro-electrodes compared to the
PEDOT
PSS and CNT:
PEDOT
PSS modified ones. EIS modeling demonstrates that the time-dependent increase in the polymeric resistance is roughly similar to the rise in the respective voltage output in vivo and indicates that the polymeric stability and conductivity, rather than the impedance due to the tissue response, is the primary factor determining the output voltage profile. It was also noted that the number of electrodes showing unit activity post-surgery did not decay for
PEDOT
TFB as was the case for
PEDOT
PSS and CNT:
PEDOT
PSS.
PEDOT
TFB may be an enabling material for achieving long lasting micro-stimulation and recording.
目的
本研究比较了导电聚合物聚（3,4 - 乙撑二氧噻吩）或PEDOT的三种变体在体外和体内条件下用于神经微刺激的稳定性。我们研究了沉积有抗衡离子四氟硼酸盐（TFB）和聚（苯乙烯磺酸盐）（PSS）的PEDOT薄膜，以及与碳纳米管（CNT）结合的PEDOT：PSS。
方法
对于体外稳定性评估，将可植入微线用聚合物涂层，置于含有磷酸盐缓冲盐水（PBS）的小瓶中，在加速老化条件（60°C）下，并施加电流脉冲。随时间监测所得电压曲线。按照相同的聚合物沉积方案，对慢性神经微探针进行修饰并植入两只大鼠的运动皮层进行体内稳定性比较。施加类似的刺激电流脉冲并检查输出电压。还记录了电化学阻抗谱（EIS）数据，并拟合到一个等效电路模型，该模型包含并量化了随时间变化的聚合物降解以及与每个微电极部位周围组织相关的阻抗。
结果
与PEDOT：PSS和CNT：PEDOT：PSS修饰的微电极相比，体外和体内电压输出曲线均显示PEDOT：TFB修饰的微电极具有相对稳定的行为。EIS建模表明，聚合物电阻随时间的增加与体内相应电压输出的增加大致相似，表明聚合物的稳定性和导电性而非组织反应引起的阻抗是决定输出电压曲线的主要因素。还注意到，术后显示单位活动的电极数量对于PEDOT：TFB没有像PEDOT：PSS和CNT：PEDOT：PSS那样衰减。PEDOT：TFB可能是实现持久微刺激和记录的一种可行材料。
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