Mesoporous Carbon Structure-Based Glass Nanopipettes as Micro pH Probes

Nanopore-based nanomaterials have been widely used to prepare the biosensor due to the unique structure, and the high sensitivity to the external stimuli under different environmental conditions. In this report, we ingeniously designed and prepared mesoporous carbon structure-based quartz nanopipettes. The mesoporous carbon was in situ grown in the tip working area of a single quartz nanopipette through the method of evaporation induced self-assembly (EISA). The mesoporous carbon could reduce the effective aperture of the nanopipette, while the surface area of nanopipette tip could be increased by the mesoporous carbon structure as well. The negative charges on the inner surface of the nanopipette increased significantly, which made the ionic current rectification of the nanopore more remarkable, with the ionic current rectification ratio increasing from 2.3 to 34.8. The mesoporous carbon-based glass nanopipette with good response to pH has been used for the probe of pH value of micro-volume solution. The test results were consistent with those obtained by using a commercial pH meter.