Efficiently transporting extracellular electrons from microbial biofilms to the electrodes is challenging and critical in achieving high‐performance microbial fuel cells (MFCs). In this work, we develop a simple and effective method to fabricate hybrid electroactive biofilms by inserting bacteria into graphene–carbon‐nanotube (G–CNT) networks (namely, G–CNT‐biofilm) as an anode for MFCs. This novel architecture greatly enhances direct extracellular electron transfer between Shewanella oneidensis and the electrode, due to strong adhesion of the hybrid conducting biofilm onto the anode surface, as well as the large surface area of graphene and the high conductivity of CNTs. A current density of 120 μA cm⁻² and a maximum power density of 97.9 μW cm⁻² are obtained in the MFC with the hybrid biofilm anode, which is significantly higher than those of a naturally growing biofilm anode (20 μA cm⁻² and 6.5 μW cm⁻²).

Highly fluorescent and bioresorbable nanoparticles formed by well-defined synthetic polycaprolactones with di(thiophene-2-yl)-diketopyrrolopyrroles exhibited enhanced photostability in cell imaging and long-term tracing.

The performance of biofilm-based bioprocesses is difficult to predict and control because of the intrinsic heterogeneous and dynamic properties of microbial biofilms. Biofilm mimics, such as microbial cells entrapped in polymeric scaffolds that are permeable for nutrients, have been proposed to replace real biofilms to achieve long-term robust performance in engineering applications. However, the physiological differences between cells that are physically entrapped in a synthetic polymeric matrix and biofilm cells that are encased in a self-produced polymeric matrix remain unknown. In this study, using Shewanella oneidensis as a model organism and alginate hydrogel as a model synthetic matrix, we compared the cell growth and protein expression in entrapped cultures and biofilms. The hydrogel-entrapped cultures were found to exhibit a growth rate comparable with biofilms. There was no substantial difference in cell viability, surface charge, as well as hydrophobicity between the cells grown in alginate hydrogel and those grown in biofilms. However, the gel-entrapped cultures were found to be physiologically different from biofilms. The gel-entrapped cultures had a higher demand for metabolic energy. The siderophore-mediated iron uptake was repressed in the gel-entrapped cells. The presence of the hydrogel matrix decreased the expression of proteins involved in biofilm formation, while inducing the production of extracellular DNA (eDNA) in the gel-entrapped cultures. These results advance the fundamental understanding of the physiology of hydrogel-entrapped cells, which can lead to more efficient biofilm mimic-based applications.