Investigating protein aggregation and determining the concentration of protein aggregates (PAs) is important in clinical studies and in the food industry. However, conventional fluorimetric methods that use amyloidophilic dyes are limited by comparatively high cost and interference from light scattering and other optically active contaminants, which can affect the reliability of measurements. This study presents an electrochemical approach to quantifying the concentration of a model PA, lysozyme aggregate (LA), by measuring the oxidation current of Thioflavin T (ThT), which LA molecules absorb. Results demonstrate that cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) provide linear detection ranges of ThT of 140 μM-1220 μM and 26 μM-170 μM, respectively. Additionally, CV studies in buffer solutions containing ThT and LA reveal that ThT-LA interaction diminishes the ThT oxidation current, enabling the detection of LA concentrations ranging from 3 μg mL to 1190 μg mL. The optimal ThT concentration for electrochemical LA detection is approximately 1 mM. These findings suggest that using ThT for electrochemical sensing of protein aggregates offers a promising alternative to fluorimetry.

Interleukin-6 (IL-6) is an important cytokine that plays a significant role in tumour growth and angiogenesis in various malignant tumours. Here, an integrated fluidic immunosensor capable of detecting the concentration of IL-6 protein in fetal bovine serum (FBS) samples using an electrochemical method in a fluidic biochip fabricated on screen-printed carbon electrodes (SPCEs) is presented. To improve the performance of the immunosensor, the SPCEs was modified with multi-walled carbon nanotubes-poly(allylamine hydrochloride)/gold nanoparticles (MWCNTs-PAH/AuNPs), which improves antibody IL-6 attachment and electron transfer efficiency. The morphological and structural properties of the nanocomposites were characterised by scanning electron microscopy (SEM) and Raman spectroscopy, while electrochemical properties were evaluated using cyclic voltammetry (CV) and square wave voltammetry (SWV). Under optimal conditions, the immunosensor exhibited a linear detection range for IL-6 protein from 0.001 to 0.1 ng mL, with a limit of detection 0.05 pg mL. Tests were performed to assess reproducibility, stability and selectivity for IL-6 in FBS samples. This immunosensor provides a sensitive, minimally invasive and simple method for the determination of clinical IL-6 protein levels. Compared to the traditional IL-6 protein batch sensor method, the approach provided by this integrated fluidic immunosensor higher sensitivity, reproducibility and faster detection.

The immobilization of enzymes is crucial for enhancing their catalytic activity and stability. Covalent organic frameworks (COF), with abundant active sites and tunable pore structures, enable effective immobilization of enzymes. Here, we designed carboxyl-functionalized COF (COF-COOH) to immobilize Cytochrome C (Cyt C), aiming to regulate the perfect pairing of the COF pore (3.67 nm) and the Cyt C dimension (2.6 nm × 3.2 nm × 3.3 nm). Meanwhile, the large amount of -COOH can increase the electrostatic and hydrogen bonding forces between COF-COOH and Cyt C. Thus, the Cyt C was efficiently loaded into COF-COOH through the post-modification method (loading efficiency = 62.37 %). The catalytic activity (k/K) of Cyt C@COF-COOH toward HO was significantly enhanced to 309.96 s M as compared to free Cyt C of 105.55 s M. The catalytic activity of Cyt C@COF-COOH toward HO still exceeds 80 % in some harsh environments (acetonitrile, dimethyl sulfoxide, tetrahydrofuran and 60 °C). The detection range of electrochemical HO biosensor based on Cyt C@COF-COOH is as wide as 2.0-80 μM, and the sensitivity is as high as 0.373 μA μM cm.

Acute kidney injury (AKI), a critical clinical syndrome marked by high incidence and mortality, is currently diagnosed mainly by serum creatinine (SCr) and blood urea nitrogen (BUN), which have high miss rates. This study innovatively proposes using urinary hydrogen peroxide (HO) concentration changes, caused by renal oxidative stress in AKI, as a new indicator for AKI risk assessment and treatment monitoring. Results from in vitro and AKI animal models show this indicator can quickly monitor AKI onset and drug effects in mice via electrochemical sensing technology based on BiS@Cu, offering a novel approach for AKI diagnosis and rehabilitation monitoring.

Nitroxoline (NXN) is an antibiotic of nitroquinoline family which is used for the treatment of urinary tract infections and as a biofilm eradicating agent. Since it shows potential antitumor activity, it is also considered a promising candidate for repurposing in cancer treatment. Present article reports on electrochemical investigations of nitroxoline, its interaction with ct-DNA using cyclic voltammetry, UV-visible spectroscopy, viscometry, molecular modelling, and thermodynamics as analytical tools. An irreversible reduction peak is observed at about -0.45 V at pH 4.0 which shifts to more negative potentials with increasing scan rate. With the addition of DNA, the signal intensity decreases indicating formation of an adduct which enabled calculation of binding constant K = (9.175±0.728) × 10 M and 2S = (0.925±0.150). Spectroscopic measurements yielded a value of (3.366±0.0.193) × 10 M. Viscosity measurements show intercalation binding mode for the drug which is supported by preliminary molecular docking studies. Thermodynamic studies reveal that ∆G° is negative and both ∆H° and ∆S° are positive, indicating spontaneity of the binding process and hydrophobic forces are dominant in binding of the drug. Electrochemical parameters, transfer coefficient (α), diffusion coefficient (D) and heterogeneous electron transfer rate (k) obtained for nitroxoline at pH 4.0 indicate mild electron transfer kinetics. Quinoline structure and nitro group are medicinally important. Present study reports for the first time qualitative and quantitative data on an important member of the quinoline family which would be of interest to researchers engaged in drug development.

This study presents an innovative and environmentally sustainable approach for treating pharmaceutical wastewater (PWW) using a dual-chamber microbial fuel cell (DMFC) that simultaneously generates bioelectricity. The DMFC system incorporates manganese cobalt oxide-coated carbon veil (MnCoO-CV) electrodes to optimize organic pollutant removal and enhance power production from PWW. The novel MnCoO-CV electrode coating represents a significant advancement, offering superior chemical stability, electrical conductivity, durability, large surface area, and enhanced absorption capacity. Following a systematic acclimatization, various organic loadings were investigated to identify optimal operating conditions. Results demonstrated peak performance at an organic loading of 2.0 g COD/L. Under these conditions, the system exhibited remarkable removal efficiencies for total chemical oxygen demand (TCOD), soluble chemical oxygen demand (SCOD), and total suspended solids (TSS), while generating electrical output. Performance evaluation encompassed maximum voltage, current density, power density, coulombic efficiency, and pollutant removal metrics. Microbial community analysis via 16S rRNA gene sequencing revealed a diverse bacterial community in the anodic biofilm that contributed to improved system performance.

Microbiologically influenced corrosion (MIC) caused by sulfate-reducing bacteria (SRB) poses a major threat to pipeline integrity in shale gas operations. Current industry standards set a control threshold of 25 cells/mL for SRB, but its scientific validity remains unclear. This study investigates the corrosion behavior of L245N steel under varying initial SRB concentrations (10 to 25 cells/mL) with 50 ppm THPS biocide presence. Results reveal a distinct threshold effect between 10 and 10 cells/mL, where corrosion severity, biofilm thickness, and sessile cell count drop sharply. Further reductions below 10 cells/mL produce negligible corrosion impact. However, there is no substantial difference between 100, 50, and 25 cells/mL, indicating a plateau effect. Sessile cell counts, biofilm morphology, electrochemical parameters, and corrosion rates all support this finding. Additionally, mixed microbial consortia enhanced SRB survival under biocidal conditions. These results suggest that the current standard may not be sufficient for MIC prevention and highlight the need for revised standards based on corrosion behavior rather than planktonic cell counts alone.

MicroRNAs (miRNAs) are crucial disease biomarkers, yet their short length, low abundance, and high sequence homology pose significant challenges for sensitive detection. Electrochemical biosensing presents a promising alternative, though effective signal amplification remains essential. This review summarizes recent advances in amplification strategies for electrochemical miRNA detection, covering nucleic acid-based techniques-such as hybridization chain reaction (HCR), rolling circle amplification (RCA), and catalytic hairpin assembly (CHA)-as well as nanomaterial-assisted approaches using metal-organic frameworks and transition metal dichalcogenides. Key mechanisms, advantages, and limitations of each method are discussed, along with performance metrics (e.g., detection limit and linear range) and emerging hybrid systems like RCA-CRISPR/Cas. Current challenges, including probe complexity and nanomaterial aggregation, are also addressed. Finally, the review highlights future directions involving multi-mechanism integration and clinical translation, offering insights for the development of highly sensitive and reliable electrochemical biosensors to advance precision medicine.

Osteosarcoma, a prevalent age-related condition, often goes undiagnosed due to expensive and invasive detection methods. This study presents a novel, cost-effective, non-invasive electrochemical sensor for Osteosarcoma detection, leveraging peptide probes to selectively recognize key biomarkers like iron ions and osteocalcin. Using a phospholipid monolayer and a conductive substrate, the sensor utilizes peptide probes containing a tripeptide iron-binding sequence and an osteocalcin sequence to detect ferroptosis-induced iron ions and elevated osteocalcin levels, both indicative of early-stage Osteosarcoma. Electrochemical modulation facilitates the covalent assembly of osteocalcin into nanoscale aggregates, significantly amplifying the sensor's signal. This design avoids the need for complex antibodies or nanomaterials, enhancing affordability and simplicity. By integrating everyday components like toothpaste to form a low baseline signal and utilizing saliva as the sample, the sensor offers high sensitivity and a low-cost alternative to traditional diagnostic methods. This innovative approach combines bioinspired materials and electrochemical techniques to provide a promising solution for early Osteosarcoma detection, addressing the pressing need for accessible diagnostics in aging populations.

In this study, we report a flexible and highly sensitive glucose sensor (CNTYs-MB/GOx) for the first time based on methylene blue (MB) and glucose oxidase (GOx) co-electrodeposited onto carbon nanotube yarns (CNTYs). Unlike conventional MB/GOx coatings on planar carbon electrodes, the three-dimensional CNTY network provides a large electroactive surface area and efficient electron transport pathways, enabling dense and uniform immobilization of the MB/GOx complex. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR) confirmed the effective capture and stabilization of GOx by MB and its homogeneous distribution on the CNTYs. This co-deposition strategy increased the active surface area 1.3-fold compared with physically adsorbed MB/GOx, resulting in significantly enhanced electrocatalytic activity. The sensor achieved a low detection limit of 25.2 μM, a wide linear range of 0.1-65 mM, excellent repeatability (RSD = 4.12 %), high selectivity (interference <5.4 %), and good long-term stability (86 % signal retention after 15 days). Moreover, it maintained a stable current response (RSD = 1.22 %) under repeated bending and mechanical deformation. In comparison of sequential electrodeposition and physical adsorption methods, this one-step co-electrodeposition enables MB and GOx to assemble synergistically on the CNTY surface, improving enzyme retention, increasing electroactive surface area, and facilitating efficient electron transfer. These results highlight the advantages of the CNTY-based co-electrodeposition approach and its potential for developing flexible, wearable glucose monitoring devices beyond traditional MB/GOx platforms.

Biofouling is significantly harmful to marine engineering equipment. Utilizing electric fields for biofouling prevention is a promising approach. Current research on electric field anti-biofouling mechanisms primarily focuses on high-voltage fields, while low-voltage alternating electric fields exhibit excellent anti-biofouling efficacy and potential. This study employs low-voltage alternating electric fields, characterized by low energy consumption, high controllability, and minimal environmental impact, to repel the typical fouling microorganisms (Phaeodactylum tricornutum). The parameters of electric field were optimized to achieve a repulsion efficiency of 97.2 %. With DCFH-DA fluorescent probes, the elevated intracellular reactive oxygen species (ROS) levels were observed after electric field treatment. Increased malondialdehyde (MDA) content confirmed the lipid peroxidation, revealing the induction of oxidative stress. Rhodamine 123 staining revealed the damage to the mitochondrial membrane in alternating electric field-treated cells, directly resulting in reduced adenosine triphosphate (ATP) levels. These results indicate that low-voltage alternating electric fields disrupts energy homeostasis via ROS-mediated mitochondrial damage, thereby inhibiting diatom adhesion. This study investigates the biological mechanism of an electric field-based anti-biofouling strategy from the perspective of cellular energy supply, highlighting the critical role of energy pathways in microbial adhesion. The findings provide theoretical support for developing next-generation anti-biofouling systems and advancing sustainable marine engineering.

Hepatitis B virus (HBV) infection remains a major global health challenge, necessitating the development of rapid, sensitive, and cost-effective diagnostics for disease and public health management. Herein, a high-performance electrochemical immunosensor for the ultratrace detection of hepatitis B surface antigen (HBsAg) is presented, leveraging laser-induced graphene (LIG) to address critical limitations of conventional diagnostics. A facile CO laser process fabricates a porous, three-electrode graphene sensor on polyimide, which is subsequently functionalized via electrochemical oxidation to introduce carboxylic groups for covalent antibody immobilization. The assay operates on the steric-hindrance principle, where immunocomplex formation impedes redox probe diffusion, quantifiable via square wave voltammetry. The platform demonstrates exceptional analytical performance: a wide linear range (1 × 10 to 1 × 10 ng mL), an ultra-low detection limit of 0.04 pg mL in buffer, and robust functionality in human serum with detection limit of 0.18 pg mL. It also exhibits outstanding selectivity against viral interferents and strong storage stability over 30 days. Combining laboratory-level sensitivity with point-of-care practicality, this biosensor offers a promising tool for early HBV screening, particularly in resource-limited settings.

This work reports the development and optimization of a tyrosinase-based amperometric biosensor for the detection of oxidizable phenols in tea infusions. The enzyme was immobilized within a hydrogel matrix composed of chitosan and mucin, crosslinked with diluted glutaraldehyde. Response Surface Methodology combined with the Desirability Function was employed to optimize the enzymatic matrix, maximizing sensitivity while minimizing response time. The optimal matrix composition corresponds to 50 % chitosan and 50 % mucin crosslinked with 5 % diluted glutaraldehyde. Different enzyme loadings were evaluated to improve the trade-off between sensitivity and linear range. Experimental and theoretical results indicated that high enzyme loadings enhanced sensitivity but restricted the linear range due to oxygen depletion and promoted phenolic polymerization near the active sites, affecting stability. Conversely, lower loadings provided extended linear ranges with only a minor effect on the detection limit. An enzymatic loading of 13 U/sensor was selected as the best compromise between sensitivity, stability, and cost. The optimized biosensor enabled rapid and reproducible quantification of oxidizable phenols in green tea, black tea, and yerba mate infusions, with analysis times below one hour. Results were consistent with literature values and highlighted the necessity of applying a standard addition method to account for matrix effects.

Microbial fuel cells (MFCs) utilize microbial metabolism to convert organic substrates into electrical energy. Saccharomyces cerevisiae presents a promising eukaryotic biocatalyst due to its fermentative capacity and non-pathogenic nature, yet its electron transfer efficiency remains a major bottleneck. This study evaluates the influence of nitrogen source variation, peptone, tryptone, and bovine serum albumin (BSA) at concentrations of 1, 2.5, and 5 mg.mL on the electrochemical performance of Saccharomyces cerevisiae-based MFCs. Half-cell analyses, including cyclic voltammetry and rate-determining step (RDS) assessments, revealed diffusion-controlled electron transfer via cytochromes. The highest electron transfer rate constant (K) was obtained with peptone 5 mg.mL (1.61 ± 0.285 s), followed by tryptone 1 mg.mL (1.53 ± 0.332 s) and BSA 1 mg.mL (0.95 ± 0.055 s). Full-cell experiments showed maximum voltage outputs of 0.132 V (peptone 5 mg.mL), 0.117 V (tryptone 1 mg.mL), and 0.039 V (BSA 1 mg.mL), and corresponding peak power densities of 46.6, 44.0, and 7.1 mW m. SEM confirmed enhanced biofilm formation with increased nitrogen concentration, supporting stronger electrochemical activity. These results highlight nitrogen source optimization as a strategic approach to enhance microbial electron transfer and energy yield in yeast-based MFC systems.

Schiff-base ligands are versatile coordination compounds with notable biological and electrochemical importance and understanding their interactions with DNA is essential for exploring their potential pharmacological and sensing applications. This study investigates the binding mechanisms between twelve structurally distinct Schiff-base ligands and calf thymus DNA (ct-DNA), emphasizing the influence of electronic and steric factors on binding affinity. Fluorescence spectroscopy, cyclic voltammetry (CV), and molecular docking were combined to evaluate binding constants, quenching behavior, and molecular interactions. Fluorescence titrations revealed moderate-to-strong binding affinities (K = 2.07-9.61 × 10 M) with predominantly static quenching. Ligands containing planar aromatic systems and electron-withdrawing substituents exhibited stronger binding, whereas bulky or methoxy-substituted analogues showed weaker interactions. These observations were further supported by CV studies, showing decreased redox currents accompanied by potential shifts upon formation of DNA-ligand complex. Molecular docking supported the experimental findings, highlighting hydrogen bonding, π-π stacking, and hydrophobic interactions as dominant stabilizing forces. Overall, the integrated spectroscopic, electrochemical, and computational analyses demonstrate a clear structure-activity relationship, establishing that ligand planarity and electronic properties are key determinants of DNA-binding strength and illustrating the potential of cyclic voltammetry as a complementary tool for studying biomolecular interactions.

In recent years, the constructed wetland-microbial fuel cell (CW-MFC) had emerged as a promising technology for antibiotic removal from water, with anode material playing a critical role in system performance. This study investigated the effects of three anode materials-activated carbon (ACCW-MFC), iron-based biochar (FCW-MFC), and pyrite (PCW-MFC)-on the removal of conventional pollutants and sulfamethoxazole (SMX), power generation, and microbial community composition. Results demonstrated that FCW-MFC achieved exceptional removal rates for COD (96.4 ± 0.68 %), TP (100 %), and SMX (100 %). FCW-MFC exhibited superior resilience to shock loads, while PCW-MFC displayed peak voltages of 402 and 399 mV before and after SMX addition, respectively. Pseudomonadota was the dominant bacterial phylum in all three MFCs (ACCW-MFC, FCW-MFC, and PCW-MFC), with relative abundances of 71.34 %, 67.26 %, and 63.35 %, respectively. Notably, FCW-MFC and PCW-MFC supported substantial populations of the denitrifying genus Thauera (27.96 % and 15.58 %, respectively). The study demonstrated that iron amendment in the anode significantly enriches the electroactive microbial community and enhanced the comprehensive performance of CW-MFCs, providing an effective strategy for simultaneous wastewater treatment and energy recovery.

The formation of Giant Unilamellar Vesicles (GUVs) is a critical technology with applications in drug delivery and the study of cellular membranes. This work presents optimized electrode designs and parameters for the electroformation of GUVs. Conventional indium tin oxide (ITO) electrodes are fragile and have limited lifespans. Meanwhile, stainless steel offers mechanical robustness, reusability, and chemical stability due to its chromium oxide layer, particularly in aqueous buffers at near-neutral pH. Here, stainless steel electrodes with different geometries were tested as a cost-effective alternative. The influence of electrode shape, alternating current (AC) frequency, and applied voltage on vesicle yield and size was systematically investigated. Four chamber configurations were evaluated and optimized for electrical resistance. Broad stainless steel mesh 30 electrodes produced the highest vesicle yield, associated with larger surface area and favorable voltage-frequency combinations. Results indicate that electrode shape and electroformation parameters significantly affect GUV characteristics. Stainless steel electrodes can replace ITO electrodes, enabling robust and scalable GUV production. This approach supports applications in biophysics, drug delivery, and biosensor development while reducing material costs and improving operational durability.

This study presents an electrochemical DNA biosensor designed for the direct, label-free, and sensitive detection of human immunodeficiency virus type 1 (HIV-1) DNA. The biosensor utilized pyrrolidinyl peptide nucleic acid (acpcPNA) probes immobilized on chitosan/glutaraldehyde-modified screen-printed carbon electrodes to facilitate the duplex invasion process with the target DNA. In the presence of the target DNA backbone, the formed duplex invasion triggered the electrostatic accumulation of a cationic hexaammineruthenium(III) redox indicator, resulting in an increased current response monitored by square wave voltammetry. The biosensor detected synthetic HIV-1 DNA within a linear range of 5-75 nM (limit of detection (LOD): 1.34 nM; limit of quantification (LOQ): 4.44 nM) and clinical HIV-1 cDNA within 10-10 copies/mL (LOD: 2.25 × 10 copies/mL; LOQ: 7.50 × 10 copies/mL), with correlation coefficients of 0.9988 and 0.9905, respectively. Importantly, the proposed platform eliminated the need for thermal denaturation and amplification while demonstrating strong selectivity against mismatched and non-target sequences, as confirmed by RT-PCR. In addition, this flexible platform enabled on-site analysis by integrating successfully with Bluetooth potentiostats and near-field communication reader chips. Given its advantages, this biosensor could serve as a promising prototype and a valuable tool for resource-limited settings requiring the detection of clinically relevant nucleic acid markers.

Most β-barrel channels exhibit voltage gating, transitioning from high- to low-conducting states under high transmembrane potentials. Unlike flexible alpha-helical channels in which a physical occlusion appears, these rigid structures lack a clear gating mechanism. Using the bacterial porin OmpF from E. coli as a model system, we reveal a non-linear dependence of gating kinetics on electrolyte concentration, explained by a model based on Debye screening with high-concentration adjustments. Also, we demonstrate a large variability in low-conducting state conductances and a striking inversion in ion selectivity, switching from cationic in the high-conducting states to anionic in the low-conducting ones. Based on this and previous data, like the lack of a defined closed-state structure with major structural changes or narrowing of the pore, we hypothesize that OmpF channel closure could be understood as an electrochemical gating process. We suggest a non-steric mechanism in which low-conducting states arise from the disruption of the electrochemical gradient occurring when the external voltage causes subtle, collective reorganizations of channel residues, leading to surface dewetting at diverse locations of the channel. This model brings ideas from solid state nanopores were gating occurs without structural movements, offering a fresh perspective on β-barrel channel closure.

Zn-InS has attracted much attention in electrochemiluminescence (ECL) due to its electronic properties, but severe carrier recombination and low content of sulfur vacancy (Sv) limit its electrocatalytic activity in the ECL process. In this study, the catalytic performance of Zn-InS for ECL process was enhanced by synthesizing Ag@Zn-InS-(3-MPA). The composite of Ag increased sulfur vacancies via electronic metal-support interaction (EMSI), which in turn enhanced the electrocatalytic activity of Zn-InS. Meanwhile the grafting of 3-mercaptopropionic acid (3-MPA) was to further enhance the electrocatalytic activity through bonding interaction and amorphization effect. All these improvements enhance the carrier separation efficiency and reduce their recombination, while facilitating the electron transfer during the generation of reactive oxygen species (ROS, e.g., *OH). This process further accelerates the electron transfer between luminol and ROS, which significantly enhances the ECL signal of luminol. A sensor for the detection of carcinoembryonic antigen (CEA) was successfully constructed using Ag@Zn-InS-(3-MPA)/luminol as a secondary antibody marker with a wide detection range and high sensitivity. The study solves the problem of low catalytic activity of Zn-InS and provides new ideas for the application of Zn-InS in the fields of electrocatalysis, photocatalysis and electrochemiluminescence.

Sediment resistivity limits the performance of sediment microbial fuel cells (SMFCs) by hindering mass electron transfer in the anodic region. This microcosm study evaluates the effect of bamboo biochar as a conductive additive at different dosages: SMFC-0 (0%), SMFC-0.1 (0.02%), SMFC-1 (0.2%), and SMFC-10 (2%). The study examines the current density, polarization behavior, redox activity, elemental composition, textural properties, anodic biofilm morphology and nutrient removal. The results show that 2% biochar (SMFC-10) increase sediment conductivity by 1.2-fold and reduces ohmic loss for mass electron transfer, achieving the highest power density (26.01 mW/m) and current output (171 mA/m). Field emission scanning electron microscopy (FESEM) analysis reveals dense anodic biofilm formation in SMFC-10, supporting higher bioelectricity generation. SMFC-10 improves pollutant removal and mitigates pollutant release into the overlying water, reducing ammonia‑nitrogen (NH-N) from 5 to 1 mg/L and chemical oxygen demand (COD) from 163 to 33 mg/L. High specific BET surface area (430.15 m/g), small pore size (1.62 nm) and high carbon content (79.46%) of biochar contribute to improve performance and long-term stability (165 days) without nutrient replenishment. These findings demonstrate that bamboo biochar is a promising sediment additive to enhance SMFC power generation and water quality.