Theoretical and experimental investigations on the interaction of epinephrine with melamine-modified carbon nanotubes†

Abstract

Functionalized carbon materials are indispensable in the development of cheap and highly selective materials for fabricating biosensors for neurotransmitters. Investigating the material–analyte interaction mechanism can improve a sensor's performance as each material has a distinct potential to interact with the analyte. In this regard, metal-free melamine-modified carbon nanotubes (MEL@CNT600) were prepared for the electrochemical detection of epinephrine (EP). The efficiency of the as-prepared material was assessed using electrochemical characterization, including cyclic voltammetry and linear sweep voltammetry. Results demonstrated that MEL@CNT600 exhibited significantly improved sensitivity (1.72 μA μM⁻¹ cm⁻²) and a detection limit as low as 1.23 μM. Several analytical and density functional theory (DFT) calculation methods were employed to elucidate the physicochemical features and the interaction mechanism of the analyte–material transduction. Theoretical insights revealed that N-rich functional groups enhanced the electron transfer rates and stabilized the adsorption of EP, contributing to the improved electrochemical response. DFT-calculated binding energies validated the experimental findings by highlighting the ideal configuration for EP interaction with the material. These findings could pave the way for further exploration of functionalized nanomaterials in the detection of biomolecules, emphasizing the role of theoretical methods in guiding experimental design. This work contributes to the growing field of electrochemical biosensing technologies, highlighting the potential of novel nanomaterials for medical diagnostics.