A Magnetic-Controlled Amperometric Biosensor Based on Composite Bio-Particulates Fe3O4 and Nano-Au With The Signal Enhancement by Increasing Loading of Horseradish

A novel amperometric biosensor was developed to determine hydrogen peroxide (H2O2) by Fe3O4/Gold nanoparticles (nano-Au)/Horseradish peroxidase (HRP) bio-particulates modified electrode. Nano-Au was assembled onto the surface of mercapto-functional Fe3O4 nanoparticles via covalent linkages between nano-Au and cysteine thiol groups. HRP was adsorbed on the nano-Au to obtain Fe3O4/nano-Au/HRP bio-particles. The biosensor was fabricated by attaching the Fe3O4/nano-Au/HRP bio-particulates on the surface of a glassy carbon electrode by an external magnetic field. H2O2 was detected by using a hydroquinone mediator to transfer electrons between the electrode and HRP. The parameters of experimental variables of the enzymatic electrode were optimized and the effects of the condition on the analytical performance were discussed. The results showed that the biosensor had a fast response of less than 10 s in a linear range of 0 to 8.0×10-4 M, and the detection limit of H2O2 was 3×10-8 M at a signal-to-noise ratio of 3. The biosensor was easily fabricated and renewed with highly sensitivity due to increased surface area for HRP loading