Disclosed is a method for preparing nanoscale electrodes comprised of electrochemically grown noble metal nanowires, and use of the same for the detection of extremely small concentrations of molecules. Such nanoscale electrodes provide target molecule release information from submicron areas on the cell surface, significantly increasing the spatial resolution of the target molecule mapping of a cell surface to enable localization of target molecules on the cell surface, which can be critical for the detection of certain cells with different properties in a given group of cells, such as circulating tumor cells.