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The last five decades of molecular and systems biology research have provided unprecedented insights into the molecular and genetic basis of many cellular processes. Despite these insights, however, it is arguable that there is still only limited predictive understanding of cell behaviours. In particular, the basis of heterogeneity in single-cell behaviour and the initiation of many different metabolic, transcriptional or mechanical responses to environmental stimuli remain largely unexplained. To go beyond the status quo, the understanding of cell behaviours emerging from molecular genetics must be complemented with physical and physiological ones, focusing on the intracellular and extracellular conditions within and around cells. Here, we argue that such a combination of genetics, physics and physiology can be grounded on a bioelectrical conceptualization of cells. We motivate the reasoning behind such a proposal and describe examples where a bioelectrical view has been shown to, or can, provide predictive biological understanding. In addition, we discuss how this view opens up novel ways to control cell behaviours by electrical and electrochemical means, setting the stage for the emergence of bioelectrical engineering.

Scanning electrochemical cell microscopy (SECCM) is used to map anodic and cathodic processes on polycrystalline zinc in 10 mM H2SO4, at the nanoscale. Electrochemical maps are correlated directly with structural data from electron backscatter diffraction applied to the same regions of the surface, and density functional theory (DFT) calculations are used to rationalize the data. Preliminary data on droplet stability with SECCM point measurements indicated that there was a significant spreading of the meniscus cell with an air atmosphere, attributed to changes in pH during the oxygen reduction reaction, compromising the lateral resolution of the SECCM measurement. Experiments with an argon atmosphere, as well as the application of a hydrophobic n-dodecane oil layer on the Zn interface, prevented spreading. Electrochemical maps of polycrystalline Zn surface under an Ar atmosphere indicated that the hydrogen evolution reaction (HER) and Zn electrodissolution on individual low-index grains decreased in the order DFT calculations revealed a correlation between experimental values of current associated with HER and Zn dissolution reactions and the predicted hydrogen adsorption and Zn dissolution energies on individual facets, respectively. This work further advances SECCM as a technique for probing electrified interfaces and demonstrates its applicability to reactive metals.

An electrochemical sensor that contains patterned regions of sp2 -carbon in a boron doped diamond (BDD) matrix is presented for the quantitative detection of hypochlorite (OCl- ) at high concentrations in the alkaline, chemically oxidizing environment associated with bleach. As BDD itself is unresponsive to OCl- reduction within the solvent window, by using a laser micromachining process it is possible to write robust electrochemically active regions of sp2 -carbon into the electrochemically inert sp3 BDD electrode. In this work, four different laser patterned BDD electrodes are examined and their response compared across a range of OCl- concentrations (0.02 M to 1.50 M). A single macro-spot (0.37 mm diameter disk) electrode and a closely spaced micro-spot (46 m diameter disk) hexagonal array electrode, containing the same surface area of sp2 -carbon, are shown to provide the most linear response towards OCl- reduction. Finite element modelling (FEM) is employed to better understand the electrochemical system, due to the complexity of the electrode geometry, as well as the need to include contributions from migration and Ohmic drop at these high concentrations. FEM data suggest that only a small percentage (~ 1×10-3 %) of the total laser-machined sp2 area is active towards the OCl- reduction process and that this process is kinetically very sluggish (~ keff = 1×10-12 cm s-1). The sensitivity at the micro-array electrode (-0.127 ± 0.004 mA M-1; R2 = 0.992) is higher than that at the single-spot (-0.075 ± 0.002 mA M-1; R2 = 0.996) due to the enhanced effect of transport to the edges of the micro-spots, shown via simulation. The electrodes returned a relatively stable response over a > three-month period of use in the OClsolutions, demonstrating these hybrid sp2 -BDD electrodes show promise for long-term monitoring applications in the harsh environments associated with bleaching applications.