The functionality of this ICB has been tested in several steps. In the first step, the applicableness of the OCB was tested by examining the SERS response from the binding of 4MPy molecules onto AuAg NPs, which yielded a similar TE-polarized SER spectrum of 4MPy to that of a previous experiment conducted with different types of silver substrates. The ability of the 4MPy-modified OCB to recognize cations in solution was verified by carrying out a time-dependent binding study of Fe 2+ .