Conductive gels based on modified agarose embedded with gold nanoparticles and their application as a conducting support for Shewanella oneidensis MR-1

Shewanella oneidensis is an electrogenic microbe which could be more widely applied in biosensing and fuel cell applications if better methods existed to promote electrode-biofilm formation. This paper reports a simple procedure that converts agarose, a cheap and readily available polymer, into a modified “MAgarose” material which will form biocompatible hydrogels that embed gold nanoparticles (AuNPs) along the fibers to yield a composite material with a conductivity ca. 80 times higher than an unmodified agarose-AuNP gel. Proof-of-concept bioelectrochemical experiments using Shewanella oneidensis show that when these MAgarose-AuNP gels are used to coat carbon veil there is a 10-fold increase in oxidative microbial current production when tested in a 3-electrode cell set-up. Microscopy results show that this can be attributed to the ability of the composite hydrogel to support MR-1 growth throughout the 3D matrix.