Composites, in which two or more material elements are combined to provide properties unattainable by single components, have a historical record dating to ancient times. Few include a living microbial community as a key design element. A logical basis for enabling bioelectronic composites stems from the phenomenon that certain microorganisms transfer electrons to external surfaces, such as an electrode. A bioelectronic composite that allows cells to be addressed beyond the confines of an electrode surface can impact bioelectrochemical technologies, including microbial fuel cells for power production and bioelectrosynthesis platforms where microbes produce desired chemicals. It is shown that the conjugated polyelectrolyte CPE‐K functions as a conductive matrix to electronically connect a three‐dimensional network of Shewanella oneidensis MR‐1 to a gold electrode, thereby increasing biocurrent ≈150‐fold over control biofilms. These biocomposites spontaneously assemble from solution into an intricate arrangement of cells within a conductive polymer matrix. While increased biocurrent is due to more cells in communication with the electrode, the current extracted per cell is also enhanced, indicating efficient long‐range electron transport. Further, the biocomposites show almost an order‐of‐magnitude lower charge transfer resistance than CPE‐K alone, supporting the idea that the electroactive bacteria and the conjugated polyelectrolyte work synergistically toward an effective bioelectronic composite.

A conjugated polyelectrolyte (poly­[2,6-(4,4-bis-potassium butanylsulfonate-4H-cyclopenta-[2,1-b;3,4-b’]-dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)], PCPDTBT-SO3K) assembles into a novel, hierarchical hydrogel structure with all structural evidence indicating dominant electrostatic rather than aromatic or mesogen interactions. PCPDTBT-SO3K forms an entangled polymer mesh, where polymer chains are tied together by ionic cross-links, comprising microgel clusters that percolate to form a macroscopic three-dimensional network. With increasing temperature, ions gain mobility to move toward the exterior of the microgel clusters, dissolving the ionic cross-links and inhibiting network percolation through electrostatic repulsion. While π–π stacking interactions may be present in a disorganized fashion, no long-range π–π stacking is evident in X-ray scattering. Soft materials based on PCPDTBT-SO3K remain semiconducting and exhibit elevated ionic conductivity at the structural reorganization temperature.

Power generation and charge storage devices are commonly uncoupled when it comes to the design of materials relevant for their fabrication. Here, it is demonstrated that the biotic–abiotic composite comprising the self‐doped conjugated polyelectrolyte CPE‐K and electrogenic bacteria Shewanella oneidensis MR‐1 can reversibly switch its function between electrical current generation in chronoamperometry mode (≈150 mA m−2) and electrochemical energy storage as a pseudocapacitor with a specific capacitance of up to 80 F g−1. Interconversion of desirable properties for the different functions is achieved by the simple addition and removal of Mg2+ in the bulk electrolyte. Potentiostatic, galvanostatic, and electrochemical impedance spectroscopy characterization, accompanied by imaging and cell viability tests, indicate that the modulation of properties is a result of reversible changes in CPE‐K macrostructures and in the number of living bacteria within the composite. The results show the possibility to realize an “on‐demand” switch between current generation and charge storage by one integrated “living” material.

Membrane protein and membrane protein–mimic functionalized materials are rapidly gaining interest across a wide range of applications, including drug screening, DNA sequencing, drug delivery, sensors, water desalination, and bioelectronics. In these applications, material performance is highly dependent on activity‐per‐protein and protein packing density in bilayer and bilayer‐like structures collectively known as biomimetic membranes. However, a clear understanding of, and accurate tools to study these properties of biomimetic membranes does not exist. This paper presents methods to evaluate membrane protein compatibility with biomimetic membrane materials. The methods utilized provide average single protein activity, and for the first time, provide experimentally quantifiable measures of the chemical and physical compatibility between proteins (and their mimics) and membrane materials. Water transport proteins, rhodopsins, and artificial water channels are reconstituted into the full range of current biomimetic membrane matrices to evaluate the proposed platform. Compatibility measurement results show that both biological and artificial water channels tested largely preserve their single protein water transport rates in biomimetic membranes, while their reconstitution density is variable, leading to different overall membrane permeabilities. It is also shown that membrane protein insertion efficiency inversely correlates with both chemical and physical hydrophobicity mismatch between membrane protein and the membrane matrix.

Organic/inorganic thermoelectric nanocomposites (TENCs) have seized great attention because they integrate the advantages of inorganic (i.e., high electrical conductivity) and organic (i.e., low thermal conductivity and mechanical flexibility) components. Major barriers that obstruct the development of this field are the lack of n‐type TE materials and their relatively low performance, leaving the construction of TE devices difficult to realize. This review article is therefore focused on recent advances on n‐type TENCs that primarily comprise carbon nanotube (CNT) and inorganic nanocrystal (NC)‐based hybrids. CNT‐based n‐type TENCs are fabricated mainly by transforming the p‐type CNT to n‐type with organic dopants or by blending CNTs with n‐type semiconducting polymers. NC‐based n‐type TENCs are typically obtained by blending semiconductor nanocrystals or metallic nanostructures with polymers. Additionally, the fabrication and thermoelectric performance of 2D layered superlattice structures are also reviewed. Finally, an outlook of n‐type TENCs is given with a perspective for their possible future improvements.