Eco-friendly surface modification of oxidized carbon nanotubes with curcumin for simultaneous electrochemical detection of dopamine and serotonin

Here we report a surface modification of oxidized carbon nanotubes (oCNTs) pre-modified on a glassy carbon electrode (GCE) with electrodeposited curcumin (CM) as a metal-free platform for simultaneous detection of dopamine (DA) and serotonin (SE). CM dissolved in an alkaline medium, was electrodeposited on various carbon-based materials and its activity towards detection of DA and SE was verified. Excellent synergy was observed between CM and oCNT towards simultaneous detection of DA and SE in pH 7 phosphate buffer saline (PBS) at 0.2 V and 0.34 V, respectively. DFT calculations also showed higher stabilization energy of the oxidized CM i.e., curcumin semiquinone (CMQ) with oCNT (3.35 eV) compared to bare CNT (2.87 eV). The CM-oCNT on a glassy carbon electrode (GCE) exhibited 4.42 times higher surface area and 60 times enhanced anodic current compared to bare GCE towards highly selective oxidative response of DA and SE with a potential difference of 158 mV. Linear calibration curves were obtained for DA and SE ranging from 10 to 170 μM and 10 to 130 μM, respectively. The research outcomes point towards possible metal-free combinations of organic moieties and carbon materials for detection of vital biomolecules in the future.