Cobalt Ferrite-Modified Nickel Foam as Electrochemical Uric Acid Sensor Towards Biological and Food Sensing Applications

Ferrites are effectively used in electrochemical uric acid (UA) sensing applications. Herein, we synthesised cobalt ferrite (CoFe 2 O 4 ) nanoparticles synthesised by one step solution combustion method. The prepared CoFe 2 O 4 was coated on nickel foam (NF) substrate to fabricate the electrode and tested using phosphate buffer saline (PBS). The small crystallite size of 14 nm as well as the large area of active sites of 0.139 cm 2 contributed towards the enhanced sensitivity of 0.735 mA.mM −1 cm −2 . The limit of detection (LOD) of CoFe 2 O 4 @NF sensor is 26.24 μM. The UA sensing occurs by an adsorption-controlled kinetics by electrostatic interaction at a pH ∼7.2 where UA anion is negatively charge while CoFe 2 O 4 surface is positively charged and it displays a quasi-reversible reaction. Additionally, the repeatability, selectivity, reproducibility of the UA sensor and the electrode kinetics were investigated. The real-time application of CoFe 2 O 4 @NF was validated using spot-urine, commercial milk and Barracuda fish samples, which show recovery percentage between 99.5% and 101.8%. The shelf-life of the CoFe 2 O 4 @NF electrode is observed to be 28 days. Hence, this highly sensitive cobalt ferrite UA sensor can be used for clinical diagnosis of hyperuricemia and food safety purposes. Combustion derived CoFe 2 O 4 coated on nickel foam substrate as a sensor. CoFe 2 O 4 @NF electrode shows adsorption-controlled kinetics. Exhibits sensitivity of 0.735 mA.mM −1 cm −2 towards uric acid detection. Developed sensor is validated for practical applications.