Electrodeposited polypyrrole/carbon nanotubes composite films electrodes for neural interfaces

The search for new electrode materials including new electrode modification methods is crucial for improving long-term performance of neuroprosthetic devices. In this study, an investigation of electrochemically co-deposited polypyrrole/single-walled carbon nanotube (PPy/SWCNT) films for improving the electrode neural interface was reported. The PPy/SWCNT microelectrodes exhibited a particularly high safe charge injection (Q(inj)) limit of similar to 7.5 mC/cm(2) and low electrode impedance at 1 kHz, as well as good stability. Cell attachment and neurite outgrowth of rat pheochromocytoma (PC12) cells on the PPy/SWCNT deposited substrates were clearly observed by Calcein-AM staining and scanning electron microscope (SEM) analysis. Furthermore, tissue response was studied by a 6-week implantation in the cortex of rats. A significantly lower (p < 0.05) glial fibrillary acidic protein (GFAP) and higher (p < 0.05) neuronal nuclei (NeuN) immunostaining were found on comparison of the test group (n = 11) with the control group (n = 8), in the zone within the distance of 100 mu m to the implant interface. All of these characteristics are desirable for chronically implantable neural probes with high density microelectrodes. Importantly, this technique can easily incorporate other modification methods to build a more advanced electrode neural interface. (C) 2010 Elsevier Ltd. All rights reserved.