4-mercaptobenzoic acid modified silver nanoparticles-enhanced electrochemical sensor for highly sensitive detection of Cu2+

In this work, a novel metal-enhanced electrochemical sensor based on silver nanoparticles (AgNPs) signal amplification was presented for highly sensitive determination of Cu2+. Gold nanoparticles were electrochemically deposited on fluorine doped fin oxide, and then 4-mercaptobenzoic acid (MBA) was self-assembled onto the surface of gold nanoislands through S-Au bond. The carboxyl of MBA could be chelated with target analyze Cu2+. Subsequently, MBA-AgNPs nanoprobes could be chelated with captured Cu2+ on the electrode as well as Cu2+ in solution through the carboxyl, forming AgNPs-MBA-Cu2+-MBA-AgNPs architecture on the electrode surface. In this way, large amount of Cu2+ were captured on the modified electrode. Herein, instead of directly probing the electro-oxidation peak of captured Cu2+, the concentration of Cu2+ was determined by measuring the electrochemical oxidation signal of AgNPs, in which MBA-AgNPs nanoprobes were used for amplification. Under optimum conditions, the electrochemistry sensor of Cu2+ performed a good linear range of 0.1-100 nM with low detection limit of 0.08 nM. In addition, the applicability of the developed sensor was evaluated by determining the concentrations of Cu2+ in tap water and pool water samples, which were consistent with the results of inductively coupled plasma-mass spectroscopy.