Spectrophotometric evaluation of gold nanoparticles as red-ox mediator for glucose oxidase

In the present research we evaluated the efficiency of gold nanoparticles (Au-NP) for enzymatic activity of glucose oxidase (GOx). Gold nanoparticles of 13 nm diameter were synthesized and characterized by atomic force microscopy (AFM). Various combinations of gold nanoparticles, glucose oxidase, red-ox mediator N-methylphenazonium methyl sulphate (PMS) and red-ox-dye 2,6-dichloroindophenol sodium salt hydrate (DCPIP) were tested. DCPIP in this system acted as an indicator and was tested by visible light absorption spectroscopy. The data obtained shows that GOx enzymatic reaction rate in the presence of 2 mu g/mL of gold nanoparticles was 1.4 times higher than the reaction rate in the absence of gold nanoparticles. Using 50 mu M of PMS rather than gold nanoparticles increased the enzyme reaction rate by 1.5 times. Moreover, gold nanoparticles together with PMS have increased the rate of GOx catalyzed enzymatic reaction up to 1.7 times. Experimental results shows that gold nanoparticles; effectively transfer electrons from GOx to DCPIP and at some conditions electron transfer via gold nanoparticles is comparable with electron transfer via red-ox mediator PMS. (C) 2009 Elsevier B.V. All rights reserved.