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

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