Bioelectrical understanding and engineering of cell biology

Metabolic adaptation pilots the differentiation of human hematopoietic cells

A continuous supply of energy is an essential prerequisite for survival and represents the highest priority for the cell. We hypothesize that cell differentiation is a process of optimization of energy flow in a changing environment through phenotypic adaptation. The mechanistic basis of this hypothesis is provided by the established link between core energy metabolism and epigenetic covalent modifications of chromatin. This theory predicts that early metabolic perturbations impact subsequent differentiation. To test this, we induced transient metabolic perturbations in undifferentiated human hematopoietic cells using pharmacological inhibitors targeting key metabolic reactions. We recorded changes in chromatin structure and gene expression, as well as phenotypic alterations by single-cell ATAC and RNA sequencing, time-lapse microscopy, and flow cytometry. Our observations suggest that these metabolic perturbations are shortly followed by alterations in chromatin structure, leading to changes in gene expression. We also show that these transient fluctuations alter the differentiation potential of the cells.

Literature review: potential non-thermal molecular effects of external radiofrequency electromagnetic fields on cancer

INTRODUCTION

There is an ongoing scientific discussion, that anti-cancer effects induced by radiofrequency (RF)-hyperthermia might not be solely attributable to subsequent temperature elevations at the tumor site but also to non-temperature-induced effects. The exact molecular mechanisms behind said potential non-thermal RF effects remain largely elusive, however, limiting their therapeutical targetability.

OBJECTIVE

Therefore, we aim to provide an overview of the current literature on potential non-temperature-induced molecular effects within cancer cells in response to RF-electromagnetic fields (RF-EMF).

MATERIAL AND METHODS

This literature review was conducted following the PRISMA guidelines. For this purpose, a MeSH-term-defined literature search on MEDLINE (PubMed) and Scopus (Elsevier) was conducted on March 23rd, 2024. Essential criteria herein included the continuous wave RF-EMF nature (3 kHz - 300 GHz) of the source, the securing of temperature-controlled circumstances within the trials, and the preclinical nature of the trials.

RESULTS

Analysis of the data processed in this review suggests that RF-EMF radiation of various frequencies seems to be able to induce significant non-temperature-induced anti-cancer effects. These effects span from mitotic arrest and growth inhibition to cancer cell death in the form of autophagy and apoptosis and appear to be mostly exclusive to cancer cells. Several cellular mechanisms were identified through which RF-EMF radiation potentially imposes its anti-cancer effects. Among those, by reviewing the included publications, we identified RF-EMF-induced ion channel activation, altered gene expression, altered membrane potentials, membrane oscillations, and blebbing, as well as changes in cytoskeletal structure and cell morphology.

CONCLUSION

The existent literature points toward a yet untapped therapeutic potential of RF-EMF treatment, which might aid in damaging cancer cells through bio-electrical and electro-mechanical molecular mechanisms while minimizing adverse effects on healthy tissue cells. Further research is imperative to definitively confirm non-thermal EMF effects as well as to determine optimal cancer-type-specific RF-EMF frequencies, field intensities, and exposure intervals.

Bioelectric control of locomotor gaits in the walking ciliate Euplotes

Diverse animal species exhibit highly stereotyped behavioral actions and locomotor sequences as they explore their natural environments. In many such cases, the neural basis of behavior is well established, where dedicated neural circuitry contributes to the initiation and regulation of certain response sequences. At the microscopic scale, single-celled eukaryotes (protists) also exhibit remarkably complex behaviors and yet are completely devoid of nervous systems. Here, to address the question of how single cells control behavior, we study locomotor patterning in the exemplary hypotrich ciliate Euplotes, a highly polarized cell, which actuates a large number of leg-like appendages called cirri (each a bundle of ∼25-50 cilia) to swim in fluids or walk on surfaces. As it navigates its surroundings, a walking Euplotes cell is routinely observed to perform side-stepping reactions, one of the most sophisticated maneuvers ever observed in a single-celled organism. These are spontaneous and stereotyped reorientation events involving a transient and fast backward motion followed by a turn. Combining high-speed imaging with simultaneous time-resolved electrophysiological recordings, we show that this complex coordinated motion sequence is tightly regulated by rapid membrane depolarization events, which orchestrate the activity of different cirri on the cell. Using machine learning and computer vision methods, we map detailed measurements of cirri dynamics to the cell's membrane bioelectrical activity, revealing a differential response in the front and back cirri. We integrate these measurements with a minimal model to understand how Euplotes-a unicellular organism-manipulates its membrane potential to achieve real-time control over its motor apparatus.

A wearable electrostimulation-augmented ionic-gel photothermal patch doped with MXene for skin tumor treatment

A wearable biological patch capable of producing multiple responses to light and electricity without interfering with daily activities is highly desired for skin cancer treatment, but remains a key challenge. Herein, the skin-mountable electrostimulation-augmented photothermal patch (eT-patch) comprising transparent ionic gel with MXene (Ti3C2Tx) doping is developed and applied for the treatment of melanoma under photostimulation at 0.5 W/cm2. The eT-patch designed has superior photothermal and electrical characteristics owing to ionic gels doped with MXene which provides high photothermal conversion efficiency and electrical conductivity as a medium. Simultaneously, the ionic gel-based eT-patch having excellent optical transparency actualizes real-time observation of skin response and melanoma treatment process under photothermal and electrical stimulation (PES) co-therapy. Systematical cellular study on anti-tumor mechanism of the eT-patch under PES treatment revealed that eT-patch under PES treatment can synergically trigger cancer cell apoptosis and pyroptosis, which together lead to the death of melanoma cells. Due to the obvious advantages of relatively safe and less side effects in healthy organs, the developed eT-patch provides a promising cost-effective therapeutic strategy for skin tumors and will open a new avenue for biomedical applications of ionic gels.

Electrical Stimulation for Immunomodulation

The immune system plays a key role in the development and progression of numerous diseases such as chronic wounds, autoimmune diseases, and various forms of cancer. Hence, controlling the behavior of immune cells has emerged as a promising approach for treating these diseases. Current modalities for immunomodulation focus on chemical based approaches, which while effective have the limitations of nonspecific systemic side effects or requiring invasive delivery approaches to reduce the systemic side effects. Recent advances have unraveled the significance of electrical stimulation as an attractive noninvasive approach to modulate immune cell phenotype and activity. This review provides insights on electrical stimulation strategies employed for regulating the behavior of macrophages, T and B cells, and neutrophils. For obtaining a better understanding, two major types of electrical stimulation sources, conventional and self-powered sources, that have been used for immunomodulation are extensively discussed. Next, the strategies of electrical stimulation that may be applied to cells in vitro and in vivo are discussed, with a focus on conventional and stimuli-responsive self-powered sources. A description of how these strategies influence the polarization, phagocytosis, migration, and differentiation of immune cells is also provided. Finally, recent developments in the use of highly localized and efficient platforms for electrical stimulation based immunomodulation are also highlighted.

Wireless electrical-molecular quantum signalling for cancer cell apoptosis

Quantum biological tunnelling for electron transfer is involved in controlling essential functions for life such as cellular respiration and homoeostasis. Understanding and controlling the quantum effects in biology has the potential to modulate biological functions. Here we merge wireless nano-electrochemical tools with cancer cells for control over electron transfer to trigger cancer cell death. Gold bipolar nanoelectrodes functionalized with redox-active cytochrome c and a redox mediator zinc porphyrin are developed as electric-field-stimulating bio-actuators, termed bio-nanoantennae. We show that a remote electrical input regulates electron transport between these redox molecules, which results in quantum biological tunnelling for electron transfer to trigger apoptosis in patient-derived cancer cells in a selective manner. Transcriptomics data show that the electric-field-induced bio-nanoantenna targets the cancer cells in a unique manner, representing electrically induced control of molecular signalling. The work shows the potential of quantum-based medical diagnostics and treatments.

Bioelectric networks: the cognitive glue enabling evolutionary scaling from physiology to mind

Each of us made the remarkable journey from mere matter to mind: starting life as a quiescent oocyte ("just chemistry and physics"), and slowly, gradually, becoming an adult human with complex metacognitive processes, hopes, and dreams. In addition, even though we feel ourselves to be a unified, single Self, distinct from the emergent dynamics of termite mounds and other swarms, the reality is that all intelligence is collective intelligence: each of us consists of a huge number of cells working together to generate a coherent cognitive being with goals, preferences, and memories that belong to the whole and not to its parts. Basal cognition is the quest to understand how Mind scales-how large numbers of competent subunits can work together to become intelligences that expand the scale of their possible goals. Crucially, the remarkable trick of turning homeostatic, cell-level physiological competencies into large-scale behavioral intelligences is not limited to the electrical dynamics of the brain. Evolution was using bioelectric signaling long before neurons and muscles appeared, to solve the problem of creating and repairing complex bodies. In this Perspective, I review the deep symmetry between the intelligence of developmental morphogenesis and that of classical behavior. I describe the highly conserved mechanisms that enable the collective intelligence of cells to implement regulative embryogenesis, regeneration, and cancer suppression. I sketch the story of an evolutionary pivot that repurposed the algorithms and cellular machinery that enable navigation of morphospace into the behavioral navigation of the 3D world which we so readily recognize as intelligence. Understanding the bioelectric dynamics that underlie construction of complex bodies and brains provides an essential path to understanding the natural evolution, and bioengineered design, of diverse intelligences within and beyond the phylogenetic history of Earth.

Metabolic and Oxidative Stress Effects on the Spectroelectrochemical Behavior of Single Pseudomonas aeruginosa Cells

Pseudomonas aeruginosa is an opportunistic human pathogen capable of causing a wide range of diseases in immunocompromised patients. In order to better understand P. aeruginosa behavior and virulence and to advance drug therapies to combat infection, it would be beneficial to understand how P. aeruginosa cells survive stressful conditions, especially environmental stressors. Here, we report on a strategy that measures potential-dependent fluorescence of individual P. aeruginosa cells, as a sentinel, for cellular response to starvation, hunger, and oxidative stress. This is accomplished using a micropore electrode array capable of trapping large numbers of isolated, vertically oriented cells at well-defined spatial positions in order to study large arrays of single cells in parallel. We find that conditions promoting either starvation or oxidative stress produce discernible changes in the fluorescence response, demonstrated by an increase in the prevalence of fluorescence transients, one of three canonical spectroelectrochemical behaviors exhibited by single P. aeruginosa cells. In contrast, more modest nutrient limitations have little to no effect on the spectroelectrochemical response when compared to healthy cells in the stationary phase. These findings demonstrate the capabilities of micropore electrode arrays for studying the behavior of single microbial cells under conditions where the intercellular spacing, orientation, and chemical environment of the cells are controlled. Realizing single-cell studies under such well-defined conditions makes it possible to study fundamental stress responses with unprecedented control.

Recent advances of cellular stimulation with triboelectric nanogenerators

Triboelectric nanogenerators (TENGs) are new energy collection devices that have the characteristics of high efficiency, low cost, miniaturization capability, and convenient manufacture. TENGs mainly utilize the triboelectric effect to obtain mechanical energy from organisms or the environment, and this mechanical energy is then converted into and output as electrical energy. Bioelectricity is a phenomenon that widely exists in various cellular processes, including cell proliferation, senescence, apoptosis, as well as adjacent cells' communication and coordination. Therefore, based on these features, TENGs can be applied in organisms to collect energy and output electrical stimulation to act on cells, changing their activities and thereby playing a role in regulating cellular function and interfering with cellular fate, which can further develop into new methods of health care and disease intervention. In this review, we first introduce the working principle of TENGs and their working modes, and then summarize the current research status of cellular function regulation and fate determination stimulated by TENGs, and also analyze their application prospects for changing various processes of cell activity. Finally, we discuss the opportunities and challenges of TENGs in the fields of life science and biomedical engineering, and propose a variety of possibilities for their potential development direction.

Low-energy amplitude-modulated electromagnetic field exposure: Feasibility study in patients with hepatocellular carcinoma

BACKGROUND

Patients with advanced hepatocellular carcinoma (HCC) and poor liver function lack effective systemic therapies. Low-energy electromagnetic fields (EMFs) can influence cell biological processes via non-thermal effects and may represent a new treatment option.

METHODS

This single-site feasibility trial enrolled patients with advanced HCC, Child-Pugh A and B, Eastern Cooperative Oncology Group 0-2. Patients underwent 90-min amplitude-modulated EMF exposure procedures every 2-4 weeks, using the AutEMdev (Autem Therapeutics). Patients could also receive standard care. The primary endpoints were safety and the identification of hemodynamic variability patterns. Exploratory endpoints included health-related quality of life (HRQoL), overall survival (OS). and objective response rate (ORR) using RECIST v1.1.

RESULTS

Sixty-six patients with advanced HCC received 539 AutEMdev procedures (median follow-up, 30 months). No serious adverse events occurred during procedures. Self-limiting grade 1 somnolence occurred in 78.7% of patients. Hemodynamic variability during EMF exposure was associated with specific amplitude-modulation frequencies. HRQoL was maintained or improved among patients remaining on treatment. Median OS was 11.3 months (95% confidence interval [CI]: 6.0, 16.6) overall (16.0 months [95% CI: 4.4, 27.6] and 12.0 months [6.4, 17.6] for combination therapy and monotherapy, respectively). ORR was 24.3% (32% and 17% for combination therapy and monotherapy, respectively).

CONCLUSION

AutEMdev EMF exposure has an excellent safety profile in patients with advanced HCC. Hemodynamic alterations at personalized frequencies may represent a surrogate of anti-tumor efficacy. NCT01686412.

The significance of bioelectricity on all levels of organization of an organism. Part 1: From the subcellular level to cells

Bioelectricity plays an essential role in the structural and functional organization of biological organisms. In this first article of our three-part series, we summarize the importance of bioelectricity for the basic structural level of biological organization, i.e. from the subcellular level (charges, ion channels, molecules and cell organelles) to cells.

Biosensors: Electrochemical Devices-General Concepts and Performance

This review provides a general overview of different biosensors, mostly concentrating on electrochemical analytical devices, while briefly explaining general approaches to various kinds of biosensors, their construction and performance. A discussion on how all required components of biosensors are brought together to perform analytical work is offered. Different signal-transducing mechanisms are discussed, particularly addressing the immobilization of biomolecular components in the vicinity of a transducer interface and their functional integration with electronic devices. The review is mostly addressing general concepts of the biosensing processes rather than specific modern achievements in the area.

Zebrafish Embryos Display Characteristic Bioelectric Signals during Early Development

Bioelectricity is defined as endogenous electrical signaling mediated by the dynamic distribution of charged molecules. Recently, increasing evidence has revealed that cellular bioelectric signaling is critical for regulating embryonic development, regeneration, and congenital diseases. However, systematic real-time in vivo dynamic electrical activity monitoring of whole organisms has been limited, mainly due to the lack of a suitable model system and voltage measurement tools for in vivo biology. Here, we addressed this gap by utilizing a genetically stable zebrafish line, Tg (ubiquitin: ASAP1), and ASAP1 (Accelerated sensor of action potentials 1), a genetically encoded voltage indicator (GEVI). With light-sheet microscopy, we systematically investigated cell membrane potential (Vm) signals during different embryonic stages. We found cells of zebrafish embryos showed local membrane hyperpolarization at the cleavage furrows during the cleavage period of embryogenesis. This signal appeared before cytokinesis and fluctuated as it progressed. In contrast, whole-cell transient hyperpolarization was observed during the blastula and gastrula stages. These signals were generally limited to the superficial blastomere, but they could be detected within the deeper cells during the gastrulation period. Moreover, the zebrafish embryos exhibit tissue-level cell Vm signals during the segmentation period. Middle-aged somites had strong and dynamic Vm fluctuations starting at about the 12-somite stage. These embryonic stage-specific characteristic cellular bioelectric signals suggest that they might play a diverse role in zebrafish embryogenesis that could underlie human congenital diseases.

Low-energy amplitude-modulated radiofrequency electromagnetic fields as a systemic treatment for cancer: Review and proposed mechanisms of action

Exposure to Low-Energy Amplitude-Modulated Radiofrequency Electromagnetic Fields (LEAMRFEMF) represents a new treatment option for patients with advanced hepatocellular carcinoma (AHCC). We focus on two medical devices that modulate the amplitude of a 27.12 MHz carrier wave to generate envelope waves in the low Hz to kHz range. Each provides systemic exposure to LEAMRFEMF via an intrabuccal antenna. This technology differs from so-called Tumour Treating Fields because it uses different frequency ranges, uses electromagnetic rather than electric fields, and delivers energy systemically rather than locally. The AutemDev also deploys patient-specific frequencies. LEAMRFEMF devices use 100-fold less power than mobile phones and have no thermal effects on tissue. Tumour type-specific or patient-specific treatment frequencies can be derived by measuring haemodynamic changes induced by exposure to LEAMRFEMF. These specific frequencies inhibited growth of human cancer cell lines in vitro and in mouse xenograft models. In uncontrolled prospective clinical trials in patients with AHCC, minorities of patients experienced complete or partial tumour responses. Pooled comparisons showed enhanced overall survival in treated patients compared to historical controls. Mild transient somnolence was the only notable treatment-related adverse event. We hypothesize that intracellular oscillations of charged macromolecules and ion flows couple resonantly with LEAMRFEMF. This resonant coupling appears to disrupt cell division and subcellular trafficking of mitochondria. We provide an estimate of the contribution of the electromagnetic effects to the overall energy balance of an exposed cell by calculating the power delivered to the cell, and the energy dissipated through the cell due to EMF induction of ionic flows along microtubules. We then compare this with total cellular metabolic energy production and conclude that energy delivered by LEAMRFEMF may provide a beneficial shift in cancer cell metabolism away from aberrant glycolysis. Further clinical research may confirm that LEAMRFEMF has therapeutic value in AHCC.

Electroactivity of weak electricigen Bacillus subtilis biofilms in solution containing deep eutectic solvent components

Bacillus subtilis is a Gram-positive, spore-forming bacterium with a versatile and adaptable metabolism, which makes it a viable cell factory for microbial production. Electroactivity has recently been identified as a cellular characteristic linked with the metabolic activity of B. subtilis. The enhancement of B. subtilis electroactivity can positively enhance bioproduction of high-added value metabolites under electrofermentative conditions. Here, we explored the use of deep eutectic solvents (DESs) and DES components as biocompatible nutrient additives for enhancing electroactivity of B. subtilis. The strongest electroactivity was obtained in an aqueous choline chloride: glycerol (1:2 mol mol^-1) eutectic mixture. At low concentration (50-500 mM), this mixture induced a pseudo-diauxic increase in planktonic growth and increased biofilm formation, likely due to a nutritional and osmoprotectant effect. Similarities in electroactivity enhancements of choline chloride-based eutectic mixtures and quinone redox metabolism in B. subtilis were detected using high performance liquid chromatography and differential pulse voltammetry. Results show that choline chloride-based aqueous eutectic mixtures can enhance biomass and productivity in biofilm-based electrofermentation. However, the specific mechanism needs to be fully elucidated.

Measurement of the low-frequency charge noise of bacteria

Bacteria meticulously regulate their intracellular ion concentrations and create ionic concentration gradients across the bacterial membrane. These ionic concentration gradients provide free energy for many cellular processes and are maintained by transmembrane transport. Given the physical dimensions of a bacterium and the stochasticity in transmembrane transport, intracellular ion concentrations and hence the charge state of a bacterium are bound to fluctuate. Here we investigate the charge noise of hundreds of nonmotile bacteria by combining electrical measurement techniques from condensed matter physics with microfluidics. In our experiments, bacteria in a microchannel generate charge density fluctuations in the embedding electrolyte due to random influx and efflux of ions. Detected as electrical resistance noise, these charge density fluctuations display a power spectral density proportional to 1/f^{2} for frequencies 0.05Hz≤f≤1Hz. Fits to a simple noise model suggest that the steady-state charge of a bacterium fluctuates by ±1.30×10^{6}e(e≈1.60×10^{-19}C), indicating that bacterial ion homeostasis is highly dynamic and dominated by strong charge noise. The rms charge noise can then be used to estimate the fluctuations in the membrane potential; however, the estimates are unreliable due to our limited understanding of the intracellular concentration gradients.

Localized electrical stimulation triggers cell-type-specific proliferation in biofilms

Biological systems ranging from bacteria to mammals utilize electrochemical signaling. Although artificial electrochemical signals have been utilized to characterize neural tissue responses, the effects of such stimuli on non-neural systems remain unclear. To pursue this question, we developed an experimental platform that combines a microfluidic chip with a multielectrode array (MiCMA) to enable localized electrochemical stimulation of bacterial biofilms. The device also allows for the simultaneous measurement of the physiological response within the biofilm with single-cell resolution. We find that the stimulation of an electrode locally changes the ratio of the two major cell types comprising Bacillus subtilis biofilms, namely motile and extracellular-matrix-producing cells. Specifically, stimulation promotes the proliferation of motile cells but not matrix cells, even though these two cell types are genetically identical and reside in the same microenvironment. Our work thus reveals that an electronic interface can selectively target bacterial cell types, enabling the control of biofilm composition and development.

Quantum information teleportation through biological wires, gravitational micro-bio-holes and holographic micro-bio-systems: A hypothesis

Biological systems like cells, bacteria, chloroplasts and other micro-organisms could exchange quantum particles like electrons, photons and gravitational waves and have large distant information teleportation. This is because that their DNAs and membranes are formed from quantum particles like electrons and protons and by their motions, some currents and waves are emerged. These waves have the main role in information teleportation. There are different methods which could be used for quantum information teleportation in biological system. Some of these mechanisms are: 1. Microbes, micro-bubbles and some other biological molecules like to form some biological lines specially near the cellular gates. Also, some biological lines may be formed between two cells. These biological lines could play the role of wires which transmit information from a place to another one. For example, some signatures of this quantum information teleportation could be seen in biological lines which are emerged near the plant cell walls or gates or close to chloroplasts. Chloroplasts shoot some spinors which maybe confined within the micro-bubbles or absorb by microbes. These bubbles and microbes may join to each other and form some biological lines which may be strengthen from a plant cell to another. These biological lines could be seen near the plant cell walls or on a metal which connects two parts of a leaf. 2. Some another signatures of “quantum photon exchange or quantum information teleportation” could be seen between microbes under the objective lenses and macro-objects on the eye lenses of a light microscope. It seems that as microscope make big images from microbes for us, produce small pictures of macro-objects for microbes such as they could diagnose them and interact with them. This property could be used in controlling microbes. 3. Another way for controlling microbes is using of virtual shapes which are induced by a special light source. For example, using a multi-gonal lamp, one can induce multi-gonal shape within the micro-bubbles. Also, this special lamp could force microbes and micro-bubbles to build multi-gonal colonies on a metal-glass slide. Maybe, by using this property, one can build a light source with the shape of anti-microbial matter and induce anti-microbial property within micro-bubbles. 4. Another main way for quantum teleportation is using of gravitational holes which may be emerged by increasing concentration of microbes and heavy cells in some points. These holes absorb microbes and micro-bubbles and conduct them to the heavy cells. Usually, there are some white holes near these dark holes which as a proposal, one can assume that these white holes are another end of gravitational holes and emit photons which are entered from dark end. 5. And finally, a very main mechanism for quantum information teleportation with microbes and controlling them is using of a holography and inducing virtual microbes and biological molecules in biological systems. For example, by a combinations of two lights with different colors under a light microscope in a dark room, one may induce some non-virtual microbes in biological systems such as each microbe interacts with a virtual microbe. This is because that light waves take photos of microbes, collide with lenses of microscopes and return to the slide and form virtual microbes or biological molecules. This technique could be used in curing diseases. Although, results of our experiments show the correctness of these mechanisms and theories, however, for the moment, we propose them only as a proposal and hypothesis and hope that other scientists do similar experiments. Also, some of our experiments may be at preliminary stages; however they could be used as a hypothesis, proposal and guidance.

Harnessing Ionic Power from Equilibrium Electrolyte Solution via Photoinduced Active Ion Transport through van-der-Waals-Like Heterostructures

Nanofluidic ion transport through van der Waals heterostructures, composed of two or more types of reconstructed 2D nanomaterials, gives rise to fascinating opportunities for light-energy harvesting, due to coupling between the optoelectronic properties of the layered constituents and ion transport in between the atomic layers. Here, a photoinduced active ion transport phenomenon through transition metal dichalcogenides (TMDs)-based van-der-Waals-like multilayer heterostructures is reported for harnessing ionic power from equilibrium electrolyte solution. The binary heterostructure comprises sequentially stacked 2D-WS₂ and 2D-MoS₂ multilayers with sub-1 nm interlayer spacing. Upon visible-light illumination, a net ionic flow is initiated through the Janus membrane, suggesting a directional cationic transport from WS₂ to MoS₂ part. The transport mechanism is explained in terms of a photovoltaic effect due to type II band alignment of WS₂ /MoS₂ heterostructures. The driving mechanism can be generally applied to a variety of heterogeneous TMD membranes with type II semiconductor heterojunctions. In equilibrium ionic solutions, the maximum ionic photoresponse approaches ≈21 µA cm^-2 and ≈45 mV under one sun equivalent excitation. Under optimized conditions, the harvested power density reaches 2 mW m^-2 . The proof-of-concept demonstration of photonic-to-ionic power generation within angstrom-scale confinement anticipates potential for light-controlled ionic circuits, artificial photosynthesis, and biomimetic energy conversion.

Bioengineering Clinically Relevant Cardiomyocytes and Cardiac Tissues from Pluripotent Stem Cells

The regenerative capacity of cardiomyocytes is insufficient to functionally recover damaged tissue, and as such, ischaemic heart disease forms the largest proportion of cardiovascular associated deaths. Human-induced pluripotent stem cells (hiPSCs) have enormous potential for developing patient specific cardiomyocytes for modelling heart disease, patient-based cardiac toxicity testing and potentially replacement therapy. However, traditional protocols for hiPSC-derived cardiomyocytes yield mixed populations of atrial, ventricular and nodal-like cells with immature cardiac properties. New insights gleaned from embryonic heart development have progressed the precise production of subtype-specific hiPSC-derived cardiomyocytes; however, their physiological immaturity severely limits their utility as model systems and their use for drug screening and cell therapy. The long-entrenched challenges in this field are being addressed by innovative bioengingeering technologies that incorporate biophysical, biochemical and more recently biomimetic electrical cues, with the latter having the potential to be used to both direct hiPSC differentiation and augment maturation and the function of derived cardiomyocytes and cardiac tissues by mimicking endogenous electric fields.

Network Thermodynamical Modeling of Bioelectrical Systems: A Bond Graph Approach

Interactions among biomolecules, electrons, and protons are essential to many fundamental processes sustaining life. It is therefore of interest to build mathematical models of these bioelectrical processes not only to enhance understanding but also to enable computer models to complement in vitro and in vivo experiments. Such models can never be entirely accurate; it is nevertheless important that the models are compatible with physical principles. Network Thermodynamics, as implemented with bond graphs, provide one approach to creating physically compatible mathematical models of bioelectrical systems. This is illustrated using simple models of ion channels, redox reactions, proton pumps, and electrogenic membrane transporters thus demonstrating that the approach can be used to build mathematical and computer models of a wide range of bioelectrical systems.

Sensing the future of bio-informational engineering

The practices of synthetic biology are being integrated into 'multiscale' designs enabling two-way communication across organic and inorganic information substrates in biological, digital and cyber-physical system integrations. Novel applications of 'bio-informational' engineering will arise in environmental monitoring, precision agriculture, precision medicine and next-generation biomanufacturing. Potential developments include sentinel plants for environmental monitoring and autonomous bioreactors that respond to biosensor signaling. As bio-informational understanding progresses, both natural and engineered biological systems will need to be reimagined as cyber-physical architectures. We propose that a multiple length scale taxonomy will assist in rationalizing and enabling this transformative development in engineering biology.

Biofilm and swarming emergent behaviours controlled through the aid of biophysical understanding and tools

Bacteria can organise themselves into communities in the forms of biofilms and swarms. Through chemical and physical interactions between cells, these communities exhibit emergent properties that individual cells alone do not have. While bacterial communities have been mainly studied in the context of biochemistry and molecular biology, recent years have seen rapid advancements in the biophysical understanding of emergent phenomena through physical interactions in biofilms and swarms. Moreover, new technologies to control bacterial emergent behaviours by physical means are emerging in synthetic biology. Such technologies are particularly promising for developing engineered living materials (ELM) and devices and controlling contamination and biofouling. In this minireview, we overview recent studies unveiling physical and mechanical cues that trigger and affect swarming and biofilm development. In particular, we focus on cell shape, motion and density as the key parameters for mechanical cell-cell interactions within a community. We then showcase recent studies that use physical stimuli for patterning bacterial communities, altering collective behaviours and preventing biofilm formation. Finally, we discuss the future potential extension of biophysical and bioengineering research on microbial communities through computational modelling and deeper investigation of mechano-electrophysiological coupling.

Scanning Ion Conductance Microscopy Reveals Differences in the Ionic Environments of Gram-Positive and Negative Bacteria

This paper reports on the use of scanning ion conductance microscopy (SICM) to locally map the ionic properties and charge environment of two live bacterial strains: the Gram-negative Escherichia coli and the Gram-positive Bacillus subtilis. SICM results find heterogeneities across the bacterial surface and significant differences among the Gram-positive and Gram-negative bacteria. The bioelectrical environment of the B. subtilis was found to be considerably more negatively charged compared to E. coli. SICM measurements, fitted to a simplified finite element method (FEM) model, revealed surface charge values of -80 to -140 mC m^-2 for the Gram-negative E. coli. The Gram-positive B. subtilis show a much higher conductivity around the cell wall, and surface charge values between -350 and -450 mC m^-2 were found using the same simplified model. SICM was also able to detect regions of high negative charge near B. subtilis, not detected in the topographical SICM response and attributed to the extracellular polymeric substance. To further explore how the B. subtilis cell wall structure can influence the SICM current response, a more comprehensive FEM model, accounting for the physical properties of the Gram-positive cell wall, was developed. The new model provides a more realistic description of the cell wall and allows investigation of the relation between its key properties and SICM currents, building foundations to further investigate and improve understanding of the Gram-positive cellular microenvironment.

100th Anniversary of Macromolecular Science Viewpoint: Soft Materials for Microbial Bioelectronics

Bioelectronics brings together the fields of biology and microelectronics to create multifunctional devices with the potential to address longstanding technological challenges and change our way of life. Microbial electrochemical devices are a growing subset of bioelectronic devices that incorporate naturally occurring or synthetically engineered microbes into electronic devices and have broad applications including energy harvesting, chemical production, water remediation, and environmental and health monitoring. The goal of this Viewpoint is to highlight recent advances and ongoing challenges in the rapidly developing field of microbial bioelectronic devices, with an emphasis on materials challenges. We provide an overview of microbial bioelectronic devices, discuss the biotic-abiotic interface in these devices, and then present recent advances and ongoing challenges in materials related to electron transfer across the abiotic-biotic interface, microbial adhesion, redox signaling, electronic amplification, and device miniaturization. We conclude with a summary and perspective of the field of microbial bioelectronics.