Layer-by-layer chitosan-decorated pristine graphene on screen-printed electrodes by one-step electrodeposition for...

Layer-by-layer chitosan-decorated pristine graphene on screen-printed electrodes was achieved by one-step electrodeposition method and an enzyme-free hydrogen peroxide electrochemical biosensor was fabricated for its application. Negatively charged pristine graphene absorbed with positively charged chitosan by electrostatic interactions was electrodeposited on the electrodes. The successful immobilization of pristine graphene was confirmed by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and electrochemical characterizations. The graphene-chitosan volume ratio and cyclic voltammetry scan cycles during the electrodeposition process were optimized. The resulting hydrogen peroxide biosensors showed a 178 times improved sensitivity and exhibited two wide linear detection ranges from 20 μM to 20 mM and from 20 mM to 60 mM. The biosensors also showed a good reproducibility, stability, selectivity and could be used in real samples detection. The superior electrochemical performance of graphene-chitosan was attributed to the preservation of excellent properties of pristine graphene, and the formation of layer-by-layer structure with high surface area. The proposed strategy of direct immobilization of pristine graphene can be extended for the immobilization of other nanomaterials and biomolecules.