Electrochemical detection of Epinephrine using Polyaniline nanocomposite films doped with TiO₂ and RuO₂ Nanoparticles on Multi-walled Carbon Nanotube

Highlights: •Electrochemical properties of functionalized MWCNT/polyaniline doped with metal oxide (TiO₂, RuO₂) nanoparticles were studied. •Techniques used include cyclic voltammetry and electrochemical impedance spectroscopy. •Au-MWCNT-PANI-TiO₂ and Au-MWCNT-PANI-RuO₂ gave the best electron transport properties. •The interference study using DPV showed clear peak separation for amino acid (AA) and EP. •Good detection of epinephrine (EP) in a pharmaceutical sample was obtained with satisfactory results. -- Abstract: Electrochemical properties of functionalized MWCNT/polyaniline doped with metal oxide (TiO₂, RuO₂) nanoparticles were explored. Successful synthesis of MWCNT, TiO_2, RuO₂, PANI, MWCNT-PANI-TiO₂, and MWCNT-PANI-RuO₂ nano materials were confirmed using suitable characterization techniques. Successful modification of gold (Au) electrode with these nanoparticles was confirmed using electrochemical techniques such as cyclic voltammetry (CV) and electrochemical impedance spectroscopy. Au-MWCNT-PANI-TiO₂ and Au-MWCNT-PANI-RuO₂ gave the best electron transport properties towards the oxidation of epinephrine (EP) compared with other electrodes investigated. The Tafel values 0.448 and 0.442 V/decade for Au-MWCNT-PANI-TiO₂ and Au-MWCNT-PANI-RuO₂ electrodes respectively in (EP) suggest adsorption due to analyte oxidation intermediates products. The linear calibration plot was obtained for EP at concentrations range 4.9 to 76.9 μM. The limits of detection of EP were estimated to be 0.16 and 0.18 μM for Au-MWCNT-PANI-TiO₂ and Au-MWCNT-PANI-RuO₂ electrodes respectively. The interference study using DPV showed clear peak separation for amino acid (AA) and EP. Therefore, the modified electrodes can selectively detect epinephrine without interference from ascorbic acid signal. The analytical performance of the fabricated sensors has been evaluated for detection of epinephrine (EP) in a pharmaceutical sample with satisfactory results.