Preparation and electrochemical characterization of a new nanosensor based on self-assembled monolayer of cysteamine functionalized with phosphate groups

Fabrication and electrochemical characterization of a self-assembled three layers modified gold electrode is described. The modification involves a three-step method; (i) preparation of cysteamine self-assembled monolayer, Au-CA, (ii) activation of Au-CA by glutaraldehyde to prepare Au-CA-GA, (iii) modification of Au-CA-GA by 2-Aminoethyl dihydrogen phosphate to functionalize the surface by phosphate groups, Au-CA-GA-AEDP. The resulting thin film modified electrode was tested successfully to recognize uranyl cations (UO22+) in aqueous solution. The cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to trace events in each step. The high affinity of the film towards the UO22+ was confirmed by EIS and CV results. The EIS data allowed recognition of UO22+ based on variation of the charge-transfer resistance (Rct) of the film as a function of the cation concentration. A dynamic range with more than three orders of magnitude was obtained.