Electrochemical click chemistry for controlled and localized biosensor surface functionalization

Abstract

Biosensor performance depends strongly on the properties of the functionalized electrode interface, making robust and controllable surface modification strategies highly desirable. In this work, we investigate electrochemical click chemistry (E-click) as an electrochemically driven route for the functionalization of sensor-relevant electrode surfaces. Using an azide-tagged fluorophore as receptor model, we demonstrate controllable surface functionalization via in situ electrochemical generation of the catalytic species. Surface modification was characterized by X-ray photoelectron spectroscopy, cyclic voltammetry, electrochemical impedance spectroscopy, and contact angle measurements, confirming successful interfacial functionalization. The influence of reaction time and applied potential on the efficiency of the E-click process was systematically examined, highlighting the importance of operating conditions that promote effective catalyst generation and surface coupling. In addition, we showed that E-click can be performed using an atomic force microscopy cantilever as the working electrode, offering a potential solution for localized micro- and nanoscale patterning with utility in preparation of multiplexed sensing interfaces. These results establish E-click as a versatile electrochemical approach for controlled electrode surface modification. Electrochemical click functionalization using Cu(I) catalyzed azide-alkyne cycloaddition of a model biosensor surface. Evolution of surface functionalization studied with X-ray photoelectron spectroscopy, cyclic voltammetry, electrochemical impedance spectroscopy, and contact angle measurements. Optimal functionalization parameters and time dependence demonstrated. Localized patterning approach with conductive AFM tip for potential multiplexed sensors.