Scanning electrochemical microscopy. 58. Application of a micropipet-supported ITIES tip to detect Ag+ and study its...

We report the use of a micropipet-supported ITIES (interface between two immiscible electrolyte solutions, also called a liquid/liquid (L/L) or water/oil (W/O) interface) as a scanning electrochemical microscopy (SECM) tip to detect silver ion and explore Ag+ toxicity in living cells. A 1,2-dichloroethane solution containing a commercially available calixarene-based Ag+ ionophore (IV) was injected into a micrometer-size glass pipet to construct an Ag+-selective SECM tip. The local Ag+ concentration, down to the micromolar level, in the vicinity of living fibroblast cells, was monitored by SECM approach curves and through imaging of the uptake and efflux of Ag+ by living fibroblast cells in real time. The results show that several stages of interaction between Ag+ and fibroblast cells exist. Since a number of biological processes of cells are involved with non-redox-active ions, the work presented here provides a new way to explore cell metabolism, drug delivery, and toxicity assessment by SECM.