Two passivation layers that coated the nanowires and a Pt layer for signal collection at the tip of the nanowires can be clearly seen in the cross-section. It is noted that the nanowire probe pierced through the cellular membrane in a bent shape, possibly due to compression by the weight of the cells. A robust passivation layer also acts as a buttress, which supports a nanowire against the cell. Figure 3c also shows that the membranes of the cells perforated VS-4718 order by the vertical nanowire probe adhere closely to the top passivation layer without any voids. This tight coupling of the membrane and the SiO2 layer prevent the cytoplasm of the GH3 cell from
mixing with the culture medium and the standard bath solution. By thus isolating the cells physically, it is possible to record the electrical selleck activity inside of the cell OICR-9429 in an intercellular mode. Conclusion We demonstrated a vertical nanowire probe can be used as a tool for intracellular probing of the electrical activity of single cells. The results indicate that interfacing of vertical grown nanowires with neuronal cells (i.e., intercellular penetration), which is essential to probe living cells in an intracellular mode, can be successfully
achieved by controlling the diameter, length, and density of the nanowires. It has been demonstrated that the device structure, which consisted of passivation layers and signal collector layers, is mechanically Selleck Atezolizumab robust and can overcome the mechanical resistance from the cells and is also electrically workable for probing the action potential. It is also shown that intracellular signaling is possible, because the nanowire probe is interposed in the GH3 cell and the cell membrane is tightly attached to the passivation layer. There have been previous studies involving vertical nanowire array electronic devices [40–42] indicating the feasibility of producing vertical nanowire
probes on a large scale. The outcomes of this study can be easily extended to the signaling of neural networks such as cultured primary neurons or brain slices, where it is necessary to measure long-term cellular activity in a large working area [43, 44]. Acknowledgements This work was supported by the National Research Foundation of Korea (NRF) grant, funded by the Korea government (MEST) (no. 2012R1A2A1A03010558) and the Pioneer Research Program for Converging Technology (no. 2009-008-1529) through the Korea Science and Engineering Foundation funded by the Ministry of Education, Science & Technology. Electronic supplementary material Additional file 1: Figure S1: TEM images of the synthesized Si nanowires. (a) Low magnitude TEM image of the Si nanowire. The diameter of Si nanowire is approximately 60 nm. (b) High-Resolution TEM image of the Si nanowire. The inset of Additional file 1: Figure S1b is a SAED pattern of the Si nanowire.