Geometric effect of copper nanoparticles electrodeposited on screen-printed carbon electrodes on the detection of α-, β- and γ-amino acids

Disposable copper nanoparticle electrodeposited screen-printed carbon electrodes (CuNPs/SPEs) capable of detecting α-, β- and γ-amino acids (AAs) are developed by a process which alternates reductive deposition and oxidative treatment over six cycles (called the RO6 method). Compared with other electrodepositing methods, the 87% ratio of RO6 method-depositing CuNPs is cubic in shape with an average edge length of 353 nm, and features a relatively higher CuI2O(2 0 0) to CuI2O face ratio of 0.17. The particular geometric characteristics of RO6-CuNPs/SPEs permit varied AA ligands to form complexes with CuI and CuII at around 0.0 V and +0.2 V, respectively. Moreover, the oxidative current induced by the CuII–AA ligand complex is larger than that induced by the CuI–AA ligand complex. Furthermore, α-AAs exhibit the faster complexation rate than β-alanine and γ-aminobutyric acid, resulting in a larger current response. The RO6-CuNPs/SPEs integrated with a flow injection analysis system exhibits high reproducibility with a relative standard deviation of 2.68%, and good linearity (correlation coefficient > 0.995) in the range of 5–1000 μM. The RO6-CuNPs/SPEs promise excellent potential for the integration of separation system to provide sensitive analysis of α-, β- and γ-AAs in clinic diagnostic and food industry applications.