Electrochemically triggered aptamer immobilization via click reaction for vascular endothelial growth factor detection

Abstract

The vascular endothelial growth factor 165 (VEGF165) is widely used as an important biomarker in cancer‐ and neuron‐related diseases. Herein, an aptamer‐based biosensor is developed that features effective protein detection. A DNA aptamer is immobilized on a gold electrode surface as recognition element utilizing an electrochemically triggered click reaction. By adjusting the applied cathodic potential, the copper catalyst can be in‐situ generated and induce a [3 + 2] cycloaddition reaction between the alkyne‐modified aptamer and the azide‐functionalized electrode surface. Compared to the commonly used thiol‐based aptamer immobilization, the present strategy facilitates a high surface probe density to (1.6 ± 0.12) × 1012 molecules/cm2 in a short period (30 min), long‐time stability (at least 1 month), as well as regenerative detection performance with an 84% current recovery in each regeneration cycle. Our work reports on a versatile strategy for the fabrication of VEGF165 aptamer‐based biosensors, which can be transferred to other aptamer‐based sensors and provides an alternative route for the immobilization of aptamer molecules to sensor surfaces.