Development of label-free electrochemical lactose biosensor based on graphene/poly(1,5-diaminonaphthalene) film

In this work, a lactose biosensor was developed by co-immobilizing beta-galactosidase (beta-Gal) and glucose oxidase (GOx) on microelectrodes pre-modified with Pt/ graphene/P(1,5-DAN) for estimation of lactose in dairy products to prevent lactose intolerance. The Pt microelectrode was modified with graphene and 1,5-polydiaminonaphthalene film. Graphene was synthesized by chemical vapor deposition on copper tape and manually transferred to the electrode surface. Polymeric P(1,5-DAN) was grafted on top of the graphene film by electropolymerization. Modified surface of the electrode was characterized by Raman spectra analysis, FE-SEM, AFM and cyclic voltammetry. The results indicated that deposition graphene film on electrode surface induced considerable enhancement in current signal, over 20 times as high as the uncoated electrode surface. The developed sensor was successfully used to determine lactose in model samples with sensitivity, correlation coefficient (R-2) and limit of detection (LOD) estimated to be 1.33 mu A/(mu gml(-1)), 0.995 and 1.3 mu g/ml, respectively. The combined graphene and conductive P(1,5-DAN) could serve as a novel sensing platform on electro-chemical sensors with superior sensitivity. (C) 2015 Elsevier B.V. All rights reserved.