Aptamer biosensor for label-free square-wave voltammetry detection of angiogenin

Angiogenin (Ang), one of the most potent angiogenic factor, is related with the growth and metastasis of numerous tumors. This paper presents a very simple and label-free square-wave voltammetry (SWV) aptasensor to detect angiogenin, in which an anti-angiogenin-aptamer was used as a molecular recognition element, and the couple ferro/ferricyanide as a redox probe. At the bare gold electrode, the redox couple (K4[Fe(CN)6]/K3[Fe(CN)6]) can be very easily accessed to the electrode surface to give a very strong SWV signal. At the anti-angiogenin/Au electrode surface, when angiogenin was added to the electrochemical cell, the binding of the analyte results in less availability for a redox reaction, which led to smaller SWV current. To quantify the amount of angiogenin, current suppressions of SWV peak were monitored using the redox couple of an [Fe(CN)6]4−/3− probe. The plot of signal suppression against the logarithm of angiogenin concentration is linear with over the range from 0.01 nM to 30 nM with a detection limit of 1 pM. The aptasensor also showed very good selectivity for angiogenin without being affected by the presence of other proteins in serum. It is the first time to use a very simple method to detect the cancer marker. Such an aptasensor opens a rapid, selective and sensitive route for angiogenin detection and provides a promising strategy for other protein detections.

► This paper presents a very simple and label-free SWV aptasensor to detect angiogenin. ► An aptamer was used as a sensing element, and the couple ferro/ferricyanide as a redox probe. ► Such an aptasensor opens a rapid, selective and sensitive route for clinical assay.