Fabrication of a kappa-carrageenan-based electroactive cytochrome c multilayer thin film by an electrostatic layer-by-layer assembly

Abstract

The aim of this study was to demonstrate the usability of kappa-carrageenan in the accumulation of a layer by layer protein film on a gold electrode. It is known that in terms of bioelectronics there are significant advantages to functional biofilms which are formed as a result of the interaction between different layer biomolecules. In this study, kappa-carrageenan (kappa-CG) was employed as the polyanion for the construction of the electroactive multilayer protein thin films. The protein layers were built up by successive adsorption of kappa-CG and cytochrome c (cyt c) based on the opposite charge on a modified gold electrode with a cyt c monolayer. Electron transport between the cyt c layers was established without the hindrance of kappa-CG. The highest electron transfer capability was achieved when the pH value of the solutions was 5, and the kappa-CG concentration was a 0.25 mg mL(-1). Whilst the amount of cyt c on the electrode surface was 10.87 pmol cm(-2) in the monolayer structure, the amount was calculated to be 158.01 pmol cm(-2) with the formation of 8-bilayer [kappa-CG/cyt c] structures over the cyt c monolayer. The multilayer protein film was also characterized using electrochemical impedance spectroscopy, ellipsometry, and UV-visible absorption spectroscopy. This novel biofilm allows a high amount of electron transfer and can be used as an immobilization platform for biosensor applications. (C) 2019 Elsevier B.V. All rights reserved.