A DNA aptasensor for electrochemical detection of vascular endothelial growth factor

Electrochemical aptasensors can detect different cancer biomarkers to provide point-of-care diagnosis that is low cost, rapid, specific and sensitive. In this work, we described the development of an electrochemical single-use aptasensor for detection and analysis of vascular endothelial growth factor (VEGF). Gold nanostructured graphite screen-printed electrodes were firstly modified with a mixed monolayer of a primary thiolated DNA aptamer and a spacer thiol, 6-mercapto-1-hexanol. VEGF protein was then incubated with the aptasensor. An enzyme-amplified detection scheme, based on the coupling of a streptavidin-alkaline phosphatase conjugate and secondary biotinylated aptamer was then applied. The enzyme catalyzed the hydrolysis of the electroinactive 1-naphthylphosphate to 1-naphthol; this product is electroactive and has been detected by means of differential pulse voltammetry (DPV). The aptasensor response was found to be linearly related to the target concentration between 0 and 250 nmol L-1 ; The detection limit was 30 nmol L-1 . The performance of the immunoassay in terms of reproducibility and selectivity has been also studied.