Fabrication of reusable sensor for detection of Cu^2+ in an aqueous solution using a self-assembled monolayer with surface plasmon resonance spectroscopy

The proposed procedure for recycling the sensor surface consists of (1) the self-assembly of 2-aminoethanethiol hydrochloride (AET) on the Au substrate, (2) the neutralization of zwitterion-like species, –NH3+Cl– to –NH2 by treatment with a NaOH solution (pH 11), (3) the detection of Cu^2+ on the NaOH-treated AET–Au substrate, and finally (4) regeneration of the sensor surface from [–NH2(right arrow) Cu^2+] to [–NH3^+Cl^–] by treatment with 1 M HCl.