A Glucose/Oxygen Enzymatic Fuel Cell based on Gold Nanoparticles modified Graphene Screen-Printed Electrode. Proof-of-Concept in Human Saliva

摘要

Highlights•A single graphene screen printed electrode-based biofuel cell has been realized.•The bioanode employ cellobiose dehydrogenase fromCorynascus Thermophilus.•The biocathode employTrametes Hirsutalaccase (ThLac) (as biocathode).•The SPEs was modified with AuNPs synthetized by “green chemistry” procedure.AbstractThis paper presents a new direct electron transfer based-miniaturized glucose/oxygen enzymatic fuel cell (EFC) whose operating ability has been tested in real saliva samples. The bioanode and biocathode are a graphene working electrode and a graphite counter electrode localized on the same screen printed electrode (SPE) modified with poly(vinyl alcohol)N-methyl-4(4′-formylstyryl)pyridinium methosulfate acetal (PVA-SbQ)/cellobiose dehydrogenase fromCorynascus Thermophilus(CtCDH) C291Y/AuNPs and withTrametes Hirsutalaccase (ThLac)/AuNPs, respectively.In order to optimize the bioanode, several CDH immobilization procedures were adopted, such as drop-casting, use of Nafion membrane or PVA-SbQ photopolymer. The photopolymer showed the best performance in terms of stability and reliability. As biocathode a partially optimized laccase electrode was employed with the variant that the used nanomaterials allowed to reduce the overpotential of O2/H2O redox reaction catalyzed byTrametes HirsutaLaccase (ThLac), drop-casted onto the gold nanoparticles (AuNPs) modified SPE.The performances of bioanode and biocathode were tested separately, initially immobilizing the two enzymes onto separated graphene SPEs. An efficient direct electron transfer was achieved for both elements, obtaining an apparent heterogeneous electron transfer rate constant (ks) of 0.99±0.05s−1forCtCDH C291Y and 5.60±0.05s−1forThLac. Both electrodes were then assembled in a two compartment EFC obtaining a maximal power output of 5.16±0.15μWcm−2at a cell voltage of 0.58V and an open circuit voltage (OCV) of 0.74V. Successively, the bioanode and biocathode were assembled in a non-compartmentalized EFC and a remarkable 50% decrease of the maximum power output at the value of 2.15±0.12μWcm−2at cell voltage of 0.48V and an OCV of 0.62V at pH 6.5 was registered. In order to reduce the cell dimensions in view of its possible integration in biomedical devices, the bioanode and biocaythode were realized by immobilization of both enzymes onto the same SPE. The so miniaturized EFC delivered a maximal power output of 1.57±0.07μWcm2and 1.10±0.12μWcm−2with an OCV of 0.58V and 0.41V in a 100μM glucose solution and in human saliva, respectively.