Polythiophene supported MnO2 nanoparticles as nano-stabilizer for simultaneously electrostatically immobilization of D-amino acid oxidase and hemoglobin as efficient bionanocomposite in fabrication of dopamine bi-enzyme biosensor

A novel, highly selective and sensitive voltammetric bi-enzyme biosensor for sensing dopamine (DA), inpresence of H2O2 which resulted as D-alanine enzymatic oxidation, was fabricated on the basis of simultaneouslyelectrostatically immobilization of D-amino acid oxidase (DAAO) and hemoglobin (Hb) on MnO2 nanoparticles (MnO2NPs) enriched poly thiophene (PTh). Cyclic voltammetry was applied for electropolymerization of thiophene on GCEsurface and MnO2 NPs dispersed on PTh network by soaking PTh/GCE in potassium permanganate (KMnO4) solution.Excellent catalytic properties and large surface area of MnO2 NPs/PTh composite caused it was used as an enzymesimmobilization host in this developed bi-enzyme biosensor. The biosensor was characterized by SEM, EDX and CVtechniques. The performance of the modified bi-enzyme biosensor was investigated in terms of its response time,detection limit, sensitivity, stability and selectivity in a lab environment. The composite of DAAO-Hb/MnO2 NPs/PThto construct a bi-enzyme biosensor in this study showed a linear response with DA in the concentration range of 0.04-9.0 μM with R-squared value of 0.994 (for S/N=3) and its sensitivity and detection limit were about 12.801 μA/μM and41 nM respectively. Also this bi-enzyme biosensors exhibited high selectivity, rapid response (5 s) and long-termstability (42 days).

کلیدواژه ها:

Bi-enzyme biosensor ، Dopamine ، MnO2 nanoparticles ، D-amino acid oxidase ، Hemoglobin ، Immobilization