Ion current rectification (ICR) is a physical phenomenon that ion current in one direction is greater than that in the other one, which can be attributed to the uneven transport of anions and cations across a nanostructure or a biological channel. ICR obtained at solid state nanopore and nanochannels has recently attracted much attention due to their potential application in fluidic logic circuits (i.e., iontronics),4-6 nanoionics and biosensors. So far, ICR has been observed and investigated in various systems, including nanopipette, conical polymer pores, conical glass pores, SiN nanochannel and protein channels. However, almost all of the reported system was focused on nanoscale since it is difficult to observe the ICR when the diameter of the pores was larger than 10 times debye lengths. Few papers have extended the ICR to micrometer scale by introducing more asymmetric factors. However, there is no report on the observation of ICR at micrometer scale for polyelectrolyte brush modified pore, although many papers have been published by modifying polyelectrolyte brush onto the inner surface of the na-nopores.

We interestingly found that micrometer scale ICR can be easily obtained at polyimidazolium brush (PimB) modified pipettes, which provides a new platform for cerebral biological molecular monitoring due to its unique property in easily in operation and relatively robust tip. In this abstract, we would like to introduce our recent research on the in vivo application of polyimidazolium-modified micropipette.