Biosensors coated with hydrogels exhibit high performance by providing structural and functional stability to the bioreceptors mounted on the sensing element. However, the volatility of the gel solvent (water) limits stable measurements. In this study, a non-volatile poly(vinyl alcohol) gel consisting of a biocompatible and non-volatile deep eutectic solvent and bound water (water-in-eutectogel) was prepared and used as the reaction medium for an enzyme sensor. To the best of our knowledge, this is the first proof-of-concept study worldwide. The water-in-eutectogel did not volatilize for more than a week at room temperature under atmospheric pressure and exhibited high ionic conductivity and mechanical strength. Moreover, a lactate oxidase-modified electrode coated with the water-in-eutectogel exhibited a lactate concentration-dependent current response with a sensitivity of 3.52 μA μM-1 cm-2 (linear range 0-1.31 μM, R2 = 0.996) and a limit of detection of 0.0673 μM. Overall, this work represents a first step toward the realization of electrochemical biosensors capable of operating in non-volatile water-in-eutectogels for biochemical analysis.
Cable bacteria are filamentous microorganisms with the unique ability to conduct electrons over centimeter-scale distances, thereby coupling spatially separated sulfide oxidation and oxygen reduction in sediments. Recent research confirms that these organisms not only perform extracellular electron transfer (EET) but also act as “biological conduits”, mediating electromicrobial interactions with other microorganisms and thus forming complex networks of electroactive microbial communities. In light of these findings, this review systematically synthesizes the core mechanisms of cable bacteria-mediated electromicrobial interactions, including the structural basis for electrical conductivity, interaction modes with flocking bacteria, the regulatory role of electron shuttles, and the synergistic effects of conductive materials. The adaptive strategies of cable bacteria and their associated communities under environmental stresses, including oxygen fluctuation, sulfide limitation, salinity variation, and physical disturbance, are summarized. We further explore the ecological effects driven by these interactions, such as the coupled cycling of sulfur, carbon, iron, and phosphorus, as well as plant-microbe symbiosis. Finally, we discuss prospects for their application in bioelectrosynthesis, particularly in pollutant degradation and optimization of microbial fuel cells. This review aims to elucidate core function of cable bacteria as “electron hubs” in ecosystems, thereby providing novel perspectives for field of electromicrobiology.
Interfaces that convert digitally defined signals into biological analog functions (D/A biointerfaces) remain underdeveloped compared with biosensors that digitize biological analog information (A/D biointerfaces). Here, we report direct electrochemical control of insulin secretion through membrane-potential modulation using a stable tetraethyl orthosilicate (TEOS)-incorporated PEDOT:PSS electrode that supports long-term culture of pancreatic β-cells as a model endocrine system. β-cells expressing luminescent insulin (iGL cells) were cultured on the electrode, and secretion dynamics were monitored by luminescence imaging during potential application. Application of +500 mV relative to the resting electrode potential (REST) rapidly reduced luminescence, indicating insulin release within seconds. Following this potential application, cells remained viable after additional culture for 3 days, retaining insulin synthesis and the ability to respond to subsequent induction. Fluorescence imaging with the membrane-potential dye FluoVolt™ suggested that the application of REST +200 mV induced depolarization comparable to that generally reported for activation of voltage-gated Ca2+ channels. Following a brief induction period, reapplication of the REST potential halted secretion. Alternating induction and REST pulses enabled stepwise modulation of cumulative insulin release. These results provide a basic operational principle for D/A biointerfaces that translate digitally programmed electrochemical inputs into analog, graded hormonal outputs.
Calcified cell walls impose structural limitations on the bioelectrochemical use of Pleurochrysis carterae (P.carterae), despite its high lipid content and CaCO₃ biomineralization capacity. In this study, P.carterae biomass was pretreated with 1-3% (v/v) H₂SO₄ for 30 min and fed to the anode of a membrane-less microbial fuel cell. Acid pretreatment increased the maximum power density from 420 to 1130 mW m-2, corresponding to approximately a 2.7-fold increase. Electrochemical analyses showed that this improvement was associated with a decrease in internal resistance, with ohmic and charge transfer resistances reduced by 78% and 90%, respectively. CV and EIS results supported enhanced electron transfer after acid pretreatment. Microbial community analysis revealed that electroactive genera such as Shewanella sp. and Desulfovibrio sp. became more abundant under high-performance conditions. Overall, these findings indicate that acid pretreatment alleviates charge-transfer limitations, improves bioelectrochemical performance, and highlight calcified microalgae as a promising biomass source for energy production and carbon management.
Electrochemical aptamer-based biosensors (E-ABs) have emerged as powerful tools for biomolecular detection, yet limited insight into binding-induced conformational dynamics has constrained their development to more efficient E-ABs. Here, we present a strategy that integrates in-silico docking with electrochemical nanoarchitecture engineering to identify optimal aptamer-target binding sites, thereby guiding the rational placement of redox labels to enhance analytical performance. Three E-AB electrodes were fabricated, each with a methylene blue placed at distinct sites within the aptamer. Electrochemical analysis revealed that the spatial positioning of redox labels critically governs the biosensing performance by modulating both binding affinity and signal transduction efficiency. Circular dichroism (CD) spectroscopy was further employed to investigate conformational changes in the engineered aptamers upon interaction with CD63, an exosomal biomarker. Notably, the configuration with a redox label positioned at the distal end achieved the lowest detection limit, the highest binding affinity, and robust performance in proof-of-concept biological models.
Understanding nanoparticle-membrane interactions is important for assessing nanotoxicity and drug delivery mechanisms. This work uses electrochemical analysis to investigate how curcumin-coated silver nanoparticles influence the biophysical properties of a gold-supported sparsely tethered Bilayer Lipid Membrane (stBLM). By monitoring gramicidin-mediated ion flux, we show that the addition of curcumin and its curcumin-coated silver nanoparticles increases the membrane ionic conductivity. A key finding is the chloride-dependent translocation of silver: at high chloride concentrations, the appearance of an Ag+/Ag redox signal indicates that silver species or derived electroactive ions penetrate the phospholipid bilayer. This process is likely driven either by the formation of neutral, passive, permeating sub-nanometer AgCl nanocrystals or by localised passive diffusion of free silver ions interacting with transient membrane boundary faults, leading to localised membrane disruption. This result provides new insights into the mechanical stability of phospholipid bilayers in the presence of metallic nanomaterials.
Sensitive electrochemical immunosensors are important for addressing global health challenges, particularly for the rapid and affordable diagnosis of infectious diseases such as dengue fever. This work reports the preparation and characterization of molybdenum disulphide/carbon nanotubes (MoS2/CNT) thin films, obtained through the liquid-liquid interfacial route, and their application as active materials in an electrochemical immunosensor for the detection of dengue virus nonstructural protein 1 (NS1), a key biomarker for early diagnosis. The nanocomposites were prepared starting from two different MoS2 samples (laboratory-synthesized or commercial) and characterized by scanning electron microscopy (SEM), X-ray diffractometry (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The film based on laboratory-synthesized MoS₂ exhibited smaller flakes, higher surface area and superior electrochemical performance compared to the commercial ones. For the immunosensor assembly, a stencil-printed, lab-made electrode was coated with the MoS₂/CNT film, followed by antibody/BSA immobilization. A label-free detection mode was adopted, and under EIS conditions, a log-linear dynamic range of 4-1000 ng mL-1 and a low detection limit of 8 ng mL-1 were achieved. High selectivity was confirmed against other arboviruses (Chikungunya and Yellow Fever), and reliable performance was achieved in diluted human serum. The proposed MoS2/CNT thin-film is a promising platform for the future development of low-cost, miniaturized, and sensitive point-of-care diagnostic devices for dengue and related infectious diseases.
Microneedle electroporation holds promise for enhancing dermal gene and drug delivery, yet the biophysical consequences of millisecond exponential-decay pulses remain incompletely characterized. We employed mid-wave infrared temperature mapping, three-dimensional electromagnetic modeling, cell viability staining, and histological analysis to systematically characterize the thermal, electrical, and biological responses of skin during microneedle electroporation. Millisecond pulsed electric fields induced pronounced, spatially heterogeneous Joule heating, with peak temperatures governed by pulse voltage and duration. A consistent voltage- and pulse-duration dependent thermal asymmetry was observed, with the anode hotter than the cathode; the anode-cathode temperature difference reached a maximum ΔT of 37.8 °C at 200 V (∼40 ms). Numerical simulations indicated that localized electric field enhancement at microneedle tips and edges contributes to these thermal effects. Biologically, anode-focused heating caused thermal charring, coagulative necrosis, and sustained inflammation, whereas electroporation-induced acute cell death remained symmetric around both electrodes. High-voltage microneedle electroporation (≥100 V) thus produces substantial localized thermal injury, particularly at the anode. These findings establish a link between transient electro-thermal dynamics and tissue injury, delineating the distinct spatial contributions of electroporation-mediated and thermal damage, and provide a biophysical basis for understanding localized Joule heating and tissue responses during millisecond-scale microneedle electroporation.
Hyaluronic acid (HA) is widely used for intra-articular injection to improve joint lubrication and mobility, but its influence on microbiologically influenced corrosion of joint implants remains unclear. Here, we investigated how HA affects the corrosion behavior of TiZr alloy in simulated body fluid (SBF) under sterile and Staphylococcus aureus (S. aureus) biofilm conditions. Surface observations and chemical analysis indicated that HA-related surface coverage was formed on the TiZr surface and reduced surface damage under sterile conditions, suggesting a protective role of HA. However, in the presence of S. aureus biofilm, HA showed contrasting effects at different immersion stages, slightly reducing corrosion at the early stage compared with the S. aureus group but aggravating biofilm-associated localized damage after prolonged exposure. Contact angle analysis showed decreases of 68.1% and 57.1% within 1 min in the S. aureus + HA group on days 7 and 14, respectively, indicating that HA promoted rapid surface wetting and altered the interfacial wetting behavior in the biofilm environment. At these time points, electrochemical tests further confirmed corrosion acceleration, with the S. aureus + HA group showing the highest corrosion current densities among all groups, reaching 7.972 × 10-6 A cm-2 and 2.715 × 10-6 A cm-2, respectively. These results demonstrate that the effect of HA on TiZr alloy corrosion shifts from protection under sterile conditions to corrosion aggravation during prolonged S. aureus biofilm exposure. This finding suggests that HA-related effects on biofilm formation and implant corrosion should be considered when assessing the corrosion risk of TiZr joint implants under infection-related conditions.
The contamination of the environment with the sulfadiazine (SDZ) antibiotic poses a significant risk to human and animal health and contributes to the emergence of drug-resistant bacteria. Conventional detection methods are often time-consuming and require sophisticated instrumentation. Herein, we developed a sensitive SDZ detection method based on a high-performance photoelectrochemical (PEC) aptasensor. Using an iron oxide (Fe3O4) functionalized three-dimensional graphitic carbon nitride (3DCN) nanocomposite. The 3DCN substrate was initially prepared through supramolecular self-assembly employing an ionic liquid as a template, followed by thermal polycondensation. Then, Fe3O4 nanoparticles bearing abundant hydroxyl groups were covalently anchored onto the 3DCN matrix via a solvothermal method. The incorporation of Fe3O4 broadened the visible-light absorption, facilitating charge separation and transport, and acting as an effective electron donor. Operating in a "signal-on" mode, the proposed aptasensor exhibited excellent analytical performance with a broad linear range (0.1 nM-1000 nM), a low detection limit (215 pM), and outstanding selectivity, stability, and reproducibility. The practical applicability was successfully validated by detecting SDZ in river water and milk with recoveries of 98.1-99.8%. Overall, the Fe3O4/3DCN-based PEC aptasensor is a robust, sensitive, cost-effective with good potential for food safety, environmental monitoring, and public health protection.
Electroporation has birthed two massive parallel universes of applications: medicine and food processing. Despite operating on the same fundamental physics, these fields fail to crosspollinate, limiting their advancement. The classical “aqueous pore” model and threshold-based definitions fail to explain the highly complex, multiparameter realities of molecular transport, cell death mechanisms, and tissue-level physiological responses. The fields often struggle to translate in vitro findings—where even varying cell lines yield conflicting results—into predictive clinical and industrial outcomes.Upscaling from small animals to humans, as well as from laboratory to industrial scale, often fails due to increasing biological complexity and variability. This translational chasm is exacerbated by a lack of multiscale and multiphysics modeling that couples electric fields with thermodynamics, fluid dynamics, and electrochemistry and most of all downstream effects of electroporation like cell death and changes in mass transport. Emerging clinical applications like Pulsed Field Ablation and therapies based on gene delivery represents a perplexing, multiparameter optimization problem that must balance electrical, thermal, and electrochemical constraints. This paper highlights critical deficiencies, explores the sharp boundary between reversible and irreversible electroporation, and calls for better reporting, standardized nomenclature, and interdisciplinary collaboration to elevate electroporation from an empirical to a universally predictive, robust science.
Therapeutic drug monitoring (TDM) of monoclonal antibodies (mAbs) is critical for realizing personalized dosing and optimizing the benefit-to-risk ratio for patients. In this work, a novel competitive electrochemiluminescence resonance energy transfer (ECL-RET) immunosensor was developed for ultra-sensitive rituximab (RTX) detection. A Zr-based metal-organic framework (Zr-MOF) was synthesized via a rapid, facile route using Zr4+ as the metal node and 9,10-di(p-carboxyphenyl)-anthracene (DPA) as the organic luminescent ligand. The as-prepared Zr-MOF exhibited durable and intense ECL output in 4-(2-Hydroxyethyl)-1-piperazineethanesulfonic acid buffer with advantages of facile synthesis, remarkable operational stability and outstanding luminescence efficiency. The CD20 epitope mimetic peptide CN-14 was selected as the recognition element for its specific binding affinity to RTX, rendering it ideal for detecting low-concentration analytes in complex biological matrices. By integrating Zr-MOF (as ECL donor) and CN-14 (as affinity ligand) with CoOOH (as ECL acceptor), the constructed ECL-RET immunosensor achieved ultra-sensitive RTX detection with a wide linear range of 1.00 × 10-4-1.00 × 102 pg mL-1 and an ultra-low limit of detection of 1.44 × 10-5 pg mL-1. This strategy provides a novel platform for advancing the detection of RTX and other therapeutic mAbs, opening new avenues for clinical TDM applications.
Pulsed-Field Ablation (PFA) is a non-thermal technique for the treatment of cardiac arrhythmias. Predictive numerical models capable of reliably predicting lesion size and shape remain limited. We introduce a biophysics-grounded and inherently anisotropic model for cardiac PFA, derived by homogenization of a microscopic electroporation model. Unlike standard approaches relying on nonlinear tissue conductivities and macroscopic electric-field-based ablation criteria, our framework naturally incorporates cellular geometry and orientation through the local transmembrane voltage, which provides a biologically meaningful criterion to predict lesion sizes. Using this transmembrane voltage-based criterion, we demonstrate that fiber-induced anisotropy strongly influences lesion morphology, leading to markedly different lesion shapes along and across the myocardial fibers. In particular, the proposed approach improves the prediction of lesion width-to-depth ratios, which are poorly captured by standard criteria. Furthermore, we propose a simple static model to account for two or more consecutive pulses. Preliminary numerical results show that the computed lesion depths are consistent with epicardial ventricular experimental observations. This work provides a mechanistic modeling framework for PFA that links cell-scale and tissue scales and highlights the importance of local tissue anisotropy.
Understanding the response of sensory neurons involved in pain perception to external stimuli is crucial for developing chronic pain treatments and determining pain thresholds. In the field of drug discovery, cultured neurons derived from human induced pluripotent stem cells (hiPSCs) are used to evaluate pain perception. Recently, three-dimensional axonal tissues derived from hiPSC-derived sensory neural spheroids have been constructed. These three-dimensional axonal tissues can mimic axon fascicles (AFs) found in the peripheral nervous system, making these tissues promising for cellular experiments aimed at overcoming interspecies differences. However, evaluations of physical and pharmacological stimulus responses, focusing on AF function, are insufficient. Here, we develop a multi-well axon array (MAA) device for hiPSC-derived sensory neural spheroids, which has four AFs, and simultaneously evaluate various stimulus responses in these fascicles. Using the MAA device, we assess temporal changes in spontaneous activity during the functional development of axonal fascicles and the responses to thermal and pharmacological stimuli targeting nociceptors. We also confirm that the MAA device allows for electrical stimulation of localized regions within AFs and detection of stimulation-evoked responses. These findings indicate that the MAA device is useful for evaluating the properties of stimulus-evoked responses of AFs.
Protein kinase A (PKA) is a key cellular signaling enzyme that transfers phosphate groups from adenosine triphosphate (ATP) to serine or threonine residues to regulate activity and downstream processes. This work presents a highly sensitive and selective electrochemical biosensor for PKA activity detection. Peptide and DNA are self-assembled on Au nanoparticles (Au NPs) via AuS bonds to form DNA-Au NPs-peptide complexes. The peptide is phosphorylated in the presence of PKA. Moreover, zirconium-metal organic framework (Zr-MOF) acts as an electrode substrate to facilitate charge transfer and molecular capture. Critically, phosphorylation allows complex immobilization on the electrode through ZrOP bonds between phosphorylated peptide and Zr-MOF. [Ru(NH3)6]3+ is electrostatically bound to DNA as an electroactive species for signal amplification. PKA activity regulates the amount of immobilized DNA, which determines the loading amount of [Ru(NH3)6]3+, and quantitative analysis is achieved by monitoring signal changes. The response signal of the biosensor exhibits a linear relationship with the logarithm of PKA concentration in the range of 0.05 to 100 U mL-1, and the limit of detection is 0.016 U mL-1. This biosensor can discriminate PKA from interferents, and allow inhibitor screening and cellular sample detection, providing a promising approach for PKA determination and inhibitor research.
Polyextremophilic microorganisms offer a promising route to overcoming the biofilm acidification and cooling costs that limit microbial electrolysis cells (MECs), yet their use is frequently hindered by electrode passivation in sulfur-rich environments. Here we investigate whether the thermophilic, acid-tolerant bacterium Desulfurella amilsii TR1ᵀ can sustain anodic current through a sulfur-mediated mechanism. We report the first description of soluble iron reduction within the class Desulfurellia; however, physiological and electrochemical analyses revealed no evidence of a significant direct electron transfer (DET) contribution under our conditions. Instead, current generation relied on a functional S0/H₂S redox shuttle. By operating the poised bioanode under sulfur-depleted conditions, the system shifted from a low-efficiency regime to a balanced state in which the coulombic efficiency increased from <5% to >42%. These results demonstrate that the typically passivating sulfur layer can be exploited as a self-regenerating, solid-phase mediator, enabling sustained energy recovery at low anode potential (+0.1 to +0.5 V vs SHE) without requiring direct electrode respiration. This work therefore establishes the anodic basis for a future sulfur-mediated MEC, while hydrogen production at a dedicated cathode remains to be demonstrated.
Cardiac troponin I (cTnI) is widely recognized as a critical biomarker for the early diagnosis of acute myocardial infarction (AMI). Consequently, the precise and sensitive detection of cTnI during the initial phases of AMI is vital. In this study, we propose the development of an advanced bipolar electrochemiluminescence (ECL)-based miniaturized, cost-effective, and optimized biosensor incorporating novel nanostructures such as MXene (Ti₃C₂Tx-TiO2) and Ce-MOF without using luminol's co-reactant (H2O2). The conjugation of Ce-MOF with MXene enhances ECL intensity due to increase in surface area and electron conductivity, respectively. Using a camera as the detection device, cTnI can be quantified within a wide range of 0.01 to 100 ng/mL. The proposed approach integrates principles of biotechnology and nanotechnology, enabling rapid and accurate quantification of this biomarker even at low concentrations and can be used for clinical diagnostics.
Accurate detection of hydrogen peroxide (H2O2), a key regulator in cellular signaling and disease progression, remains challenging due to its low concentration and high reactivity. In this study, a photoelectrochemical (PEC) sensor based on defect-engineered, fluoride-free anodic TiO2 nanotube arrays was developed for sensitive H2O2 detection. Ordered TiO2 nanotubes were prepared via electrochemical anodization and annealing, followed by electrochemical reduction to introduce oxygen vacancies and Ti3+ defects. Characterization confirmed that the nanotube structure and anatase phase were retained, while defect density increased with reduction time, leading to enhanced conductivity, charge separation, and PEC activity. The optimized sample (TiO2-600-r150) exhibited the highest photocurrent response, indicating an optimal defect concentration. It demonstrated a linear detection range up to 0.7 mM, with a sensitivity of 76.49 μA mM-1 cm-2 and a detection limit of 14.0 μM. Additionally, the sensor showed excellent selectivity and maintained stable performance in diluted cell culture media. These results highlight the critical role of defect engineering in improving PEC performance and demonstrate the potential of TiO2-based sensors for reliable H2O2 detection in biological systems.
In the gas field, steel corrosion issues induced by sulfate-reducing bacteria (SRB) are a crucial factor in pipeline service failure. The effect of condensate oil on SRB corrosion in CO2-containing gas field environments at high temperatures remains unknown. In this work, the inhibition behavior of SRB corrosion at 60 °C induced by condensate oil in the CO2-saturated artificially tight gas produced water was investigated in-depth. The experimental results indicated that SRB can maintain a certain level of bioactivity in the test solution at 60 °C, although the cell concentrations appear to decrease. The uniform and localized corrosion of steel in the CO2-saturated solution containing SRB shows an acceleration, but the addition of condensate oil mitigates it. In the environments containing SRB, the density of corrosion pits with a value of (5.56 ± 0.38) × 102 pits·cm-2 and the corresponding maximum localized corrosion rate of (0.143 ± 0.018) mm/y are found, but these values decrease to (3.78 ± 0.38) × 102 pits·cm-2 and (0.091 ± 0.018) mm/y after the addition of condensate oil. A new insight into the understanding of steel corrosion in the gas condensate reservoirs containing CO2, condensate oil, and SRB at high temperatures is presented in this study.
Photobioelectrochemistry couples light-harvesting and electrochemical materials with biological catalysts to convert solar energy into fuels, chemicals, and recoverable resources. A central premise is that photobioelectrochemical performance depends on how biological catalysts, photoactive materials, interfacial charge-transfer pathways, and operating environments are coupled, rather than on any component in isolation. The biotic-abiotic interface and reactor context provide the basis for comparing recent advances in biological catalysts, engineered photoactive interfaces, and reactor configurations. These advances are discussed with particular focus on solar fuel generation, CO₂ conversion and upgrading, and the use of waste and wastewater streams for value recovery, nutrient capture, bioproduction, and bioremediation. Across these systems, the review examines how interface design, electrode architecture, and reactor conditions control the delivery of photogenerated charge to biological catalysts, thereby influencing activity, selectivity, and stability. By linking interfacial charge transfer with biological function and reactor-level constraints, this review aims to identify design considerations that can support the transition of photobioelectrochemical systems from isolated demonstrations to practical sustainable biotechnology applications.
