Copper staining/labeling and scanning electrochemical microscopy readout of proteins on poly(vinylidene difluoride) membranes

Scanning Electrochemical Microscopy (SECM) is used in combination with copper labeling to visualize roteins on surfaces. Proteins are adsorbed on a poly(vinylidene difluoride) (PVDF) membrane and stained using a standard protocol involving copper salts. The latter are then reduced to copper metal and further detected by SECM with ferrocene methanol as a redox mediator in aqueous solution. During the SECM scan, the potential is held at a value at which the oxidation of the redox mediator occurs and a positive feedback current is detected when scanning over copper clusters. A negative feedback is observed elsewhere.