Electrocatalytic oxidation of L-Dopa by novel biosensor based on immobilization of HRP on nucleophilic-functionalized MWCNT composite

A novel and selective enzymatic biosensor was designed and constructed for voltammetric determination of levodopa (L-Dopa) in aqueous media (phosphate buffer solution, pH=7).Biosensor development was on the basis of to physically immobilizing of horse radish peroxidase (HRP) as electro chemical catalyst by sol-gel on glassy carbon electrode modified with organic nucleophilic carbon nanotube composite which in this composite p-Phenylenediamine (pPDA) as organic nucleophile chemically bonded with functionalized MWCNT (MWCNT-COOH). The differential pulse voltammetry (DPV) was used fordetermination of L-Dopa from 0.1 μM to 1.9 μM with a low detection limit of 40 nM (for S/N=3) and sensitivity was about 35.5μA/μM. Developed biosensor was suitably stable for about 60 days. The developed biosensor was characterized by SEM, energy dispersive X-ray analysis (EDX), FT-IR spectroscopy and CVs.

Keywords:

HRP biosensor , Nucleophilic functionalized carbon nanotube , Levodopa , Sol-gel