A Sensitive Biosensor for Determination of Cu²⁺ by One-step Electrodeposition

A simple one-step electrodeposition method is described to fabricate three dimensional ordered macroporous chitosan−prussian blue−single walled carbon nanotubes (3DOM CS−PB−SWCNTs) film onto the gold electrode surface to fabricate a copper ions (Cu²⁺)-specific DNAzyme biosensor. The new sensing strategy for sensitive and selective detection of Cu²⁺ was based on Au nanorods (AuNRs) as signal amplification labels. The electrochemical signal of glucose increased with the concentration of Cu²⁺ increasing. The morphologies and electrochemistry of the composites were investigated by using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electrochemical techniques including cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) and so on. Linear correlations of copper ion concentration were obtained in the range from 10⁻¹⁸ M to 10⁻⁵ M, achieving with a limit of detection of 10⁻¹⁹ M (S/N=3). Parameters affecting the biosensor response such as temperature, the cleavage time and the time of hybridization were optimized. This biosensor showed a wide range, low detection limit, good reproducibility and high stability. Additionally, these striking properties endow the biosensor with a great promise for analytical applications.