Conventional methods to engineer electroconductive hydrogels (ECHs) through the incorporation of conductive nanomaterials and polymers exhibit major technical limitations. These are mainly associated with the cytotoxicity, as well as poor solubility, processability, and biodegradability of their components. Here, we describe the engineering of a new class of ECHs through the functionalization of non-conductive polymers with a conductive choline-based bio-ionic liquid (Bio-IL). Bio-IL conjugated hydrogels exhibited a wide range of highly tunable physical properties, remarkable in vitro and in vivo biocompatibility, and high electrical conductivity without the need for additional conductive components. The engineered hydrogels could support the growth and function of primary cardiomyocytes in both two dimentinal (2D) and three dimensional (3D) cultures in vitro. Furthermore, they were shown to be efficiently biodegraded and possess low immunogenicity when implanted subcutaneously in rats. Taken together, our results suggest that Bio-IL conjugated hydrogels could be implemented and readily tailored to different biomedical and tissue engineering applications.

Photocorrosion of semiconductors is strongly sensitive to the presence of surface states, and it could be influenced by electrically charged molecules immobilized near the semiconductor/electrolyte interface. The underlying mechanism is related to band bending of the semiconductor structure near the surface and the associated distribution of excited electrons and holes. The authors have employed photoluminescence of GaAs/AlGaAs quantum heterostructures for monitoring in situ the photocorrosion effect, and demonstrating detection of nongrowing Legionella pneumophila suspended in phosphate buffered saline solution. Antibody functionalized samples allowed direct detection of these bacteria at 10(4) bacteria/ml. The authors discuss the sensitivity of the process related to the ability of creating conditions suitable for photocorrosion proceeding at extremely slow rates and the interaction of an electric charge of bacteria with the surface of a biofunctionalized semiconductor.

The net electric charge associated with a bacterial strain is primarily defined by the number of available functional groups at its surface and we observed that it can determine the limit of detection of a charge-sensing biosensor. We have investigated the dynamic range of bacterial electric charge variations through binding negatively charged sodium dodecyl sulphate (SDS) molecules, with the objective of improving the detection limit of a charge-sensing GaAs/AlGaAs nanoheterostructure biosensor designed for detection of Legionella pneumophila. A twofold increased zeta potential of L. pneumophila was measured at pH 7.4 following the exposure of these bacteria to an SDS solution at 0.02 mg/mL. Subsequently, it was possible to detect SDS decorated and heatinactivated L. pneumophila at 10 3 CFU/mL. This illustrates the fundamental role of the bacterial electric charge in the operation of photocorrosion-based III-V semiconductor biochips. We discuss the mechanisms of bacterial interaction with SDS, critical aspects of decorating bacteria with this anionic surfactant and the channels responsible for charge transfer.