Surface Functionalization of Glassy Carbon Electrodes via Electrografting of Aminobenzoic Acid: A Proof‐of‐Concept Study for Aptasensor Design

This study explores a carbon‐based electrode alternative of conventional gold‐thiolate monolayers for high‐throughput biosensor development. We investigate the functionalization of glassy carbon electrodes (GCEs) with aptamers to create biosensing interfaces. The modification process of carbon involves three main steps: (1) electrografting of 4‐aminobenzoic acid (ABA) onto the electrode surface to introduce carboxyl (–COOH) groups, (2) –COOH groups activation using EDC/NHS chemistry, and (3) coupling 5 ′ ‐amine‐terminated aptamers for tobramycin (apt‐TOB). Surface modification of the resulting GCE/ABA/aptamer was characterized rigorously using cyclic voltammetry (CV), water contact angle, electrochemical impedance spectroscopy (EIS), and attenuated total reflectance‐Fourier transform infrared (ATR‐FTIR) spectroscopy. The obtained interface exhibits an exceptional surface coverage of ≈170 pmol cm −2 , exceeding that of conventional gold‐thiolate monolayers. As a proof of concept, we demonstrate the impedimetric detection of tobramycin using the GCE/ABA/aptamer‐modified electrodes. The range of detection achieved was 1 nM–10 μM and a LOD of 1 nM. This work aims to evaluate the feasibility of using ABA (via carbodiimide chemistry) as a linker for aptamer immobilization on GCE, like a practical alternative to gold for high‐performance aptamer‐based sensors in clinical, ambiental, and alimentary analyses.