One-step detection of alpha fetal protein based on gold microelectrode through square wave voltammetry

The detection of tumor markers in blood samples with high efficiency and sensitivity is in urgent need. In this work, a one-step quantitative detection assay for alpha fetal protein (AFP) based on gold microelectrode which is denoted as Au mu E through square wave voltammetry using [Fe(CN)(6)](3)(-/)(4-) as mediator was developed. As the biorecognition element of the assay, sulfydryl-modified AFP aptamer could be directly conjugated onto the surface of the Au mu F, which could capture AFP with high specificity, and this attachment would cause the decrease of the capacitive current of the cyclic voltammetry due to the reduction of the active area of the electrodes. Under the optimized conditions, the Au mu E aptasensor exhibited a linear detection range for AFP from 10(-10) to 10(-7) g/mL = 7.6 nA/dec, R-2 = 0.991), and the detection limit is 2.5 x 10(-11) g/mL. The Au mu Es aptasensor demonstrates good selectivity against other types of proteins and small molecules, and has good reproducibility. The real blood samples were used for detection of AFP using the Au mu Es aptasensor, the results agree well with those provided by the hospital through electrochemiluminescence method. Herein, the proposed one-step detection assay has a great application potential in point-of-care clinical diagnostics.