Characterization of Ag+ toxicity on living fibroblast cells by the ferrocenemethanol and oxygen response with the scanning electrochemical microscope

The viability of living fibroblast cells cultured on a Petri dish was determined by scanning electrochemical microscopy (SECM). Three kinds of feedback modes for single living cells were derived with different redox couples: positive, negative and consumptive. The consumptive feedback was unique and distinguished uptake from the response caused by cell deformation. The toxicity of Ag+ ion on the living fibroblast cells was investigated by using both ferrocenemethanol (FcMeOH) and oxygen (O2) as electrochemical mediators. The results showed that Ag+ ions could be taken up and then reduced to form sub-micrometer and micrometer sized metal silver particles. The metal silver particles stained fibroblast cells and give a positive feedback with FcMeOH. These were also identified by the results of both SECM and energy dispersive X-ray spectroscopy (EDX). The amount of consumption of dissolved O2 decreased with time, showing the cell status as the cells died. Since O2 is directly involved in cell metabolism and the products of O2 reduction are not re-oxidized by metal silver particles trapped on fibroblast cells, it is a good SECM mediator to characterize drug effects on cell viability. The results suggest the importance of choice of redox mediator in characterizing cell viability.