XPS was performed to further study the surface chemistry of the 4-ATP/Cu as well as the attachment of the SWCNT/Cu. The survey scan for both samples show no spurious peaks confirming the cleanness of the deposition of the 4-ATP over the copper substrate and the reaction leading to the attachment of the SWCNT over copper. The main peaks for the 4-ATP over copper are: 284, 531, 164 and 399 eV for C1s, O1s, S2p, and N1s, respectively . Fig. 7A present the high SB431542 scans of the previously listed elements for the extracellular route 4-ATP/Cu. Here, the curve fitting spectra of the C1s spectrum, considering three band contributions at 284.6, 285.4, and 286.8 eV. The main C1s line appears at 284.6 eV, which corresponds to the CC bond and the CS bond corresponding to the aromatic ring. The peak at 285.4 eV corresponds to CN bond . The high resolutions scan for N1s shows one peak corresponding to the nitrogen main peak at 399.3 eV characteristics of the amine group on the aromatic molecule (CH2-NH2)  and .