Sensitive electrochemical immunosensor based on three-dimensional nanostructure gold electrode

Guangxian Zhong,^1,2,* Ruilong Lan,^3,* Wenxin Zhang,^1,4 Feihuan Fu,⁵ Yiming Sun,^1,4 Huaping Peng,^1,4 Tianbin Chen,³ Yishan Cai,⁶ Ailin Liu,^1,4 Jianhua Lin,² Xinhua Lin<sup>1,4

1</sup>Department of Pharmaceutical Analysis, Faculty of Pharmacy, Fujian Medical University, ²Department of Orthopaedics, ³The Centralab, First Affiliated Hospital of Fujian Medical University, ⁴Nano Medical Technology Research Institute, Fujian Medical University, Fuzhou, ⁵Department of Endocrinology, The County Hospital of Anxi, Anxi, ⁶Fujian International Travel Healthcare Center, Fujian Entry-Exit Inspection and Quarantine Bureau, Fuzhou, People’s Republic of China

*These authors contributed equally to this work

Abstract: A sensitive electrochemical immunosensor was developed for detection of alpha-fetoprotein (AFP) based on a three-dimensional nanostructure gold electrode using a facile, rapid, “green” square-wave oxidation-reduction cycle technique. The resulting three-dimensional gold nanocomposites were characterized by scanning electron microscopy and cyclic voltammetry. A “sandwich-type” detection strategy using an electrochemical immunosensor was employed. Under optimal conditions, a good linear relationship between the current response signal and the AFP concentrations was observed in the range of 10–50 ng/mL with a detection limit of 3 pg/mL. This new immunosensor showed a fast amperometric response and high sensitivity and selectivity. It was successfully used to determine AFP in a human serum sample with a relative standard deviation of <5% (n=5). The proposed immunosensor represents a significant step toward practical application in clinical diagnosis and monitoring of prognosis.

Keywords: electrochemical immunosensors, three-dimensional nanostructure gold electrode, square-wave oxidation-reduction cycle, alpha-fetoprotein