Preparation of Biocompatible Palladium-Fe 3O 4 Nanoparticles/Multiwalled Carbon Nanotubes Composite and its Electrocatalytic Activity towards Determination of Cholesterol on Screen Printed Electrode

A simple and facile microwave method was adopted to prepare Fe 3O 4 and Pd- Fe 3O 4 nanoparticles, which possess the mean particle diameter of 10 nm and 90 nm, respectively. Formation of Fe 3O 4 and Pd- Fe 3O 4 nanoparticles were confirmed from Powder X-ray diffraction, Transmission electron microscopy, Energy-dispersive X-ray spectroscopy, and FT-Infra red spectroscopy techniques. Negatively charged mutliwalled carbon nanotubes (COO--MWCNTs) were wrapped with positively charged poly (Diallyldimetheylammonium Chloride) (PDDA) followed by coating with Pd-Fe 3O 4 nanoparticle to get (Pd-Fe 3O 4/PDDA/COO - -MWCNTs) composite. This composite was used for the determination of cholesterol by using Cholesterol Oxidase (ChOx) enzyme on Screen Printed Electrode (SPE). (Pd- Fe 3O 4/PDDA/COO - -MWCNTs) composite provides biocompatible microenvironment for the ChOx to exhibit Direct Electron Transfer (DET) on electrode surface. A well defined redox peak at -0.365 and -0.443 V was observed, corresponding to the DET of the FAD/FADH2 of ChOx. Enzyme modified SPE was characterized by cyclic voltammetry and electrochemical impedance spectroscopy by means of Fe(CN)6 3-/4as an electrochemical probe. The linear range of the enzyme modified SPE was found to be 10-80 μm (R=0.9972) with detection limit of 1 μm of cholesterol. The sensitivity of the enzyme modified SPE was found to be 10.45 μA μM-1 cm -2 for the determination of cholesterol, common interferents such as ascorbic acid, uric acid and glucose did not cause any interference because of low operating potential. Keywords: Pd-Fe 3O 4; Nanoparticles; Screen Printed Electrode; Cholesterol Oxidas