Optimization of gold nanostructure preparation for heavy metal sensing

Heavy metal contamination of drinking water is a serious environmental and public health problem worldwide, requiring sensitive and reliable analytical techniques that can be adapted for on-site field use. Gold nanostructure– based electrochemical sensors provide promising solutions because of the chemical stability of gold, its excellent electrochemical properties, and its compatibility with biological functionalization. In this work, the electrochemical deposition of gold nanostructured sensing layers is investigated with a strong focus on in-situ spectroscopic ellipsometry as a real-time quantitative monitoring tool. Electrodeposition parameters were optimized to control the morphology of the gold nanostructures, followed by protein immobilization to enable selective heavy metal binding, especially for nickel. Ellipsometric modeling based on effective medium approaches implemented in the CompleteEASE software allowed continuous tracking of layer formation during electrochemical processing. The sensing concept was demonstrated through cyclic voltammetry measurements in the presence of Ni(II) ions, showing clear and reproducible electrochemical responses.