Electron Transfer Mediator Research Articles

Fabrication and characterization of electrically conducting electrochemically synthesized polypyrrole-based enzymatic biofuel cell anode with biocompatible redox mediator vitamin K3

Enzymatic biofuel cells (EBFCs) hold tremendous potential to power biomedical devices, biosensors, and bioelectronics. Unlike conventional toxic batteries, these electrochemical devices are biocompatible, harnessing energy from physiological fluids and producing usable electrical energy. But the commercialization of EBFCs is limited by the low operational stability, limited power output and poor electron transport efficiency of the enzymatic electrodes. In this study, a novel bioanode exhibiting a high electron transfer ability and long-term stability was fabricated. For the preparation of the anode, surfactant-assisted polypyrrole (PPy) was electrochemically co-deposited on a platinum wire with the simultaneous entrapment of vitamin K3 (VK3) and GOx (glucose oxidase) in the PPy matrix. Herein, conducting PPy acts as an electron transfer enhancer and provides appropriate electrical communication between the active site of the enzyme glucose oxidase (GOx) and the electrode surface. Biocompatible redox mediator vitamin K3 was employed as an electron transfer mediator to shuttle electrons between the oxidized fuel glucose and surface of the electrode in the electrochemical cell. The electrical conductivity of PPy was measured using the four-probe technique of conductivity measurement of semiconductors. The morphological characterization of as-synthesized anode (PPy/CTAB/VK3/GOx) was performed by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The electrochemical characterization was studied by cyclic voltammetry (CV), linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) techniques. It was observed that the room-temperature conductivity of PPy lies in the semiconducting range and it also shows good stability on exposure to laboratory air, making it a promising material to provide electrical contact. The study developed a bioanode producing a modest current density of 6.35 mA cm–2 in 20 mM glucose solution. The stability, current output and ease of manufacturing process of the electrode make it particularly suitable for employment in biofuel cell applications.

Fe(III) oxyhydroxides mediated electron transfer from thiols to O2 for hydroxyl radical production

Thiols serve as important electron reservoirs in subsurface environments, playing an important role in biogeochemical cycling of redox-sensitive elements. Nevertheless, due to the kinetic constraint on thiol oxidation by O2, hydroxyl radical (•OH) production during thiol oxygenation had long been disregarded. •OH is the most powerful oxidant in natural environment, capable of oxidizing most of inorganic and organic pollutants. This study revealed that Fe(III) oxyhydroxides could mediate electron transfer from thiols to O2, thereby facilitating •OH production within a pH range of 3 to 9. For instance, at pH 7, the presence of 1 g/L ferrihydrite increased •OH accumulation from <0.2 to 15.3 μM within 10 h during the oxygenation of 6 mM cysteine. This enhancement resulted from Fe(III) oxyhydroxides altering the •OH production pathway from the direct oxidation of thiols by O2 to the oxidation of adsorbed Fe(II) by O2. In natural soils, Fe(III) oxyhydroxides were estimated to contribute to 69–81% of thiol removal and to 56–82% of •OH production. Furthermore, the •OH produced during thiol oxygenation also exhibited the capability to degrade phenol. This study highlights the previously overlooked catalytic role of Fe(III) oxyhydroxides in facilitating thiol oxidation and •OH production.

A genetic engineering strategy to enhance outer membrane vesicle-mediated extracellular electron transfer of Geobacter sulfurreducens

Bioelectrochemical systems (BESs) are unique devices that harness the metabolic activity of electroactive microorganisms (EAMs) to convert chemical energy stored in organic substrates into electrical energy. Enhancing electron transfer efficiency between EAMs and electrodes is the key to practical implementation of BESs. Considering the role of outer membrane vesicles (OMVs) in mediating electron transfer of EAMs, a genetic engineering strategy to achieve OMVs overproduction was explored to enhance electron transfer efficiency and the underlying mechanisms were investigated. This study constructed a mutant strain of Geobacter sulfurreducens that lacked the ompA gene encoding an outer membrane protein. Experimental results showed that the mutant strain produced more OMVs and possessed higher electron transfer efficiency in Fe(III) reduction, dye degradation and current generation in BESs than the wild-type strain. More cargoes such as c-type cytochromes, functional proteins, eDNA, polysaccharides and signaling molecules that might be favorable for electron transfer and biofilm formation were found in OMVs produced by ompA-deficient anodic biofilm, which possibly contributed to the improved electron transfer efficiency of ompA-deficient biofilm. The results indicate that overproduction of OMVs in EAMs might be a potential strategy to enhance BESs performance.

Pseudocapacitance behavior enables efficient and stable electrochemical energy conversion and storage in glucose/air enzymatic biofuel cells

Constructing an integrated system with high-efficiency and stable energy conversion and storage (ECS) is of great significance but remains challenges. Herein, we report a biodevice consisting of a bioanode of tetrathiafulvalene/glucose oxidase (TTF/GOx) immobilized on asphalt-derived porous carbon (APC) for catalyzing glucose oxidation and a biocathode of 2,2’-azinobis(3-ethylbenzothiazoline-6-sulfonate)/bilirubin oxidase (ABTS/BOD) immobilized on APC for catalyzing oxygen reduction, to achieve ECS with high-efficiency and excellent stability. The redox mediators, TTF and ABTS, used at the bioanode and biocathode, respectively, simultaneously mediate electron transfer to release electric current on discharging and serve as pseudocapacitors to achieve charge storage at open-circuit conditions, enabling high power density and self-charge capability. The biodevice of the above configuration delivers a peak power output of 5.01 mW cm−2 in the pulse discharge mode with cell voltage remaining 93.7 % of its initial value after 100 pulse discharge/self-charge cycles. This work provides a highly efficient solution to address the low power density and poor stability of the conventional enzymatic biofuel cells, showing great implications for small, implantable and wearable electronics.

Overlooked Hydrogen Bond in a Blue Copper Protein Uncovered by Neutron and Sub-Ångström Resolution X-ray Crystallography.

Metalloproteins play fundamental roles in organisms and are utilized as starting points for the directed evolution of artificial enzymes. Knowing the strategies of metalloproteins, by which they exquisitely tune their activities, will not only lead to an understanding of biochemical phenomena but also contribute to various applications. The blue copper protein (BCP) has been a renowned model system to understand the biology, chemistry, and physics of metalloproteins. Pseudoazurin (Paz), a blue copper protein, mediates electron transfer in the bacterial anaerobic respiratory chain. Its redox potential is finely tuned by hydrogen (H) bond networks; however, difficulty in visualizing H atom positions in the protein hinders the detailed understanding of the protein's structure-function relationship. We here used neutron and sub-ångström resolution X-ray crystallography to directly observe H atoms in Paz. The 0.86-Å-resolution X-ray structure shows that the peptide bond between Pro80 and the His81 Cu ligand deviates from the ideal planar structure. The 1.9-Å-resolution neutron structure confirms a long-overlooked H bond formed by the amide of His81 and the S atom of another Cu ligand Cys78. Quantum mechanics/molecular mechanics calculations show that this H bond increases the redox potential of the Cu site and explains the experimental results well. Our study demonstrates the potential of neutron and sub-ångström resolution X-ray crystallography to understand the chemistry of metalloproteins at atomic and quantum levels.

Efficient hydroxyl radical production and sulfanilamide degradation during oxygenation of microbially reduced metal–organic frameworks

Incubation of iron-reducing bacteria with Fe(III) could generate •OH to decompose organic pollutants under redox fluctuation conditions. However, the Fe(III)/Fe(II) transformation efficiency and therefore yields of •OH production in systems using Fe(III)-bearing minerals as respiration substrate of bacteria is unsatisfying. Here, we showed that different iron- and iron-copper-based metal–organic frameworks (Fe-MOFs and FeCu-MOFs) can mediate electron transfer from Shewanella oneidensis MR-1 to O2 through their Fe(III)/Fe(II) cycling during anoxic–oxic transition, resulting in generation of reactive oxygen species including •O2–, H2O2 and •OH. While 3 g/L of MIL-101(Fe) demonstrated faster Fe(III)/Fe(II) cycling, better yields of •OH production (69.0 μmol/mmol Fe(II) oxidation) and sulfanilamide removal (81.5 % in 24 h) than iron-bearing minerals and the rest two Fe-MOFs (MIL-53(Fe) and MIL-88B(Fe)), Fe0.75Cu0.25-B surpassed the performance of MIL-101(Fe) and other FeCu-MOFs with different Fe/Cu ratios, which might be attributed to its larger surface area, higher amounts of associated Fe(II), and synergistic effects between Fe and Cu species. Moreover, both MIL-101(Fe) and Fe0.75Cu0.25-B maintained structure stability and persistent catalytic activity during four continuous redox cycles in 48 h, the •OH production and sulfanilamide degradation of which exceeded those of one-time operation in the same duration. This study revealed the efficacy of combining bacteria and MOFs for •OH production, and provided promising alternatives for oxidative degradation of contaminants.

Mediated electron transfer in a photo-bioreactor: continuous flow hydroxylation using cytochrome P450 BM3 in NADPH-free conditions

We designed a proof-of-concept photo-bioreactor enabling continuous flow NADPH-free activation of cytochrome P450 BM3 via mediated electron transfer.

Nano silver oxide-modified activated carbon as a novel catalyst for efficient removal of bacteria and micropollutants in aquatic environment.

Heterogeneous Fenton process is a promising water treatment technology for sterilization and degradation of organic pollutants, due to the strong oxidation of hydroxyl radicals (OH˙) generated. However, the low H2O2 activation efficiency and the instability of catalyst leading to low OH˙ production restricted development of this technology. Herein, we synthesized a novel porous activated carbon-loaded nano silver oxide (nAg2O/AC) catalyst to enhance the activation of H2O2 for removing bacteria (E. coli) and micropollutants (Tetracycline, TC) from water. In the nAg2O/AC Fenton system, reductive hydroxyl groups on AC accelerated Ag(i)/Ag cycle through mediated electron transfer, which markedly increased H2O2 activation efficiency to 73.7% (About 2.9 times that of traditional Fenton). Hence, nAg2O/AC Fenton achieved up to 6.0 log and 100% removal efficiency for E. coli and TC, respectively. The OH˙ as the major oxidizing species in nAg2O/AC Fenton system was detected and verified by radical scavenging tests and electron spin resonance (ESR) measurement. After 4 and 5 cycles of experiments, the removal of E. coli and TC still reached 5.2 log and 96%, respectively, confirming good stability of nAg2O/AC for considerable application prospects. This study concluded that nAg2O/AC is a promising H2O2 catalyst for simultaneous removal of bacteria and micropollutants in aqueous environment.

Re-assessing viologens for modern bio-electrocatalysis.

Viologens, 1,1'-disubstituted-4,4'-bipyridinium salts, are organic redox species that can be used in place of NADPH as mediators for redox enzymes. In this study, using the reduction of oxidized glutathione by glutathione reductase as a model system, a rationally designed library of viologens covering a range of polarities and functional groups were explored as electron transfer mediators for bio-electrocatalysis. Through a series of electrochemical investigations, the reduction potential was found to be the primary determining factor for electron transfer between the viologen and enzyme. Through enhancing the solubility of viologen such that the fully reduced state remained soluble, we demonstrate a much-widened window of useable viologen potentials. In doing so, we describe for the first time a highly efficient electron transfer to a flavoenzyme promoting the catalytic reaction in the absence of co-factors. As such, our study provides a platform for broadening the scope for using viologens as mediating agents for electrochemically-driven enzymatic processes.

A dye sensitized photosynthesis cell for stable water oxidation mediated by photo-generated bromine.

The critical step of a dye-sensitized photoelectrochemical cell (DSPEC) is water oxidation. The photoanodes suffer rapid surface carrier recombination due to slow water oxidation kinetics and this results in low solar conversion efficiency and poor stability. Here, we design a novel sensitization-oxidation photo-anode, where the [Ru(4,4'-PO3H2-bpy)(bpy)2]2+ (RuP2+, bpy = 2,2'-bipyridine) chromophore and [Ru(bda)(pic)2] (pic = picoline, bda = 2,2'-bipyridine-6,6'-dicarboxylate) water oxidation catalyst (WOC) are immobilized separately on the surface of a mesoporous semiconductor thin film. The electrode creates a mobile and strong Br3- oxidant generated by the dye-sensitized electrode, which initiates water oxidation at a remote catalytic site. Under 100 mW cm-2 illumination in pH 4.65 in 0.1 M acetate buffer solution, the photoanode could perform a stable photoelectrochemical water oxidation for 6 hours with a photocurrent density of around 0.25 mA cm-2. This dual electrode could open a new door by utilizing an electron transfer mediator to design highly stable photoelectrochemical cells.

Main extracellular electron carrier between Desulfovibrio sp. Huiquan2017 and low alloy steels

Desulfovibrio species have been proposed to be able to accept electrons from Fe0 via a mediated electron transfer (MET) process. Electron shuttles that mediate MET were investigated by using dialysis bags to separate the low alloy steel EH40 from the bacterium D. sp. Huiquan2017 in the same liquid system. The weight losses of coupons immersed in the bacteria-free side were found to be significantly higher than those in the abiotic media, whereas they were similar when the molecular weight cutoff of the dialysis bags was between 30,000 D and 100 D. In the bacterial culture high consumption of H2 was found, however, riboflavin and flavin mononucleotides were not detected. Furthermore, expressions of genes encoding periplasmic hydrogenases in the biofilms on the EH40 steel were clearly upregulated. These results suggest that the bacterium D. sp. Huiquan2017 may receive electrons from Fe0 via H2 as the main electron shuttle and the periplasmic hydrogenases may be involved in the oxidation of the extracellular-derived H2.

Magnetite-equipped algal-rich sediments for microbial fuel cells: Remediation of sediment organic matter pollution and mechanisms of remote electron transfer

Using the bio-electrochemical methods for the restoration of high algae sediments is full of potential and challenges. How to promote extracellular electron transfer (EET) process in microbial fuel cells (MFC) is the key bottleneck. The study had explored the potential application of magnetite on accelerating electron transfer for improving the output of MFC and sediment pollution remediation. The results indicated that the organic matter degradation rate showed a remarkable increase of 27.45 %, and the voltage output was approximately 1.68 times higher compared to the MFC configured with regular sediment. Abundant electroactive bacteria (EABs), such as Geobacter and Burkholderiaceae, and fermentative bacteria were responsible for these results, accompanied by the enhanced fluorescence of humic substances (HS), increased concentration and activity of cytochrome C (25.05 % and 21.12 %), as well as elevated extracellular polymeric substance content. Moreover, the intrinsic EET mechanisms among Fe-oxides, HS, and EABs were explored. According to the electrochemical analysis and substance transformation, the EET process involved four stages: magnetite-enhanced direct electron transfer via strong conductivity, iron respiration mediating electron transfer to the electrode, the model quinone substance acting as an electron shuttle facilitating EET and iron reduction, and iron cycling mediating electron transfer. This study provides an effective strategy for pollution remediation in algal-rich sediment, which was beneficial for the harmless treatment and resource utilization of both algae and sediment, simultaneously.

Ultrathin CuNi2Al-LDH nanosheets with enhanced electron transfer for visible-light-driven photo-fenton-like water decontamination

The Cu-based photo-Fenton-like process stands out as a promising technology for water decontamination, but its catalytic efficiency for refractory organic pollutants removal still suffers from shortage of Cu(I) supply in the activation of H2O2. Herein, we, for the first time, developed ultrathin nanosheets of Cu(I)-enrich CuNi2Al layered double hydroxides (CuNi2Al-LDH) with fast electron transfer rate to achieve superior visible-light-driven photo-Fenton catalytic performance. In the brucite-like sheets of LDH, the electron donation effect of Ni enabled the electron transfer from Ni to Cu, resulting in generation of 62.9 % Cu(I) content, which provided abundant Cu(I) active sites for Fenton-like reaction. Notably, the coexistence of Ni and Cu ions in the nanosheets significantly enhanced the visible-light harvesting ability by d-d transitions, thereby boosting the production of photogenerated carriers. More importantly, the Ni sites with excellent electroactivity served as electron-transfer mediators to remarkably promote the photogenerated carriers charge separation and photogenerated electrons transfer, leading to nearly 20 times improvement in the photocurrent density of CuNi2Al-LDH in comparison to the Ni-free LDH, which greatly expedited the Cu(II)/Cu(I) cycle and promoted H2O2 activation. Benefiting from these advantages, CuNi2Al-LDH could degrade 100 % of phenol, tetracycline (TC) and dyes within 30 min at room temperature through the synergy effect of photocatalysis and Fenton oxidation, and the reactive oxygen species •OH, •O2− and 1O2 contributed 44.2 %, 12.9 % and 37.7 % to the degradation of pollutants, respectively. This study provides an ingenious strategy to the rational design of on-demand multifunctional catalysts for advanced water remediation.

Avoiding Potential Pitfalls in Designing Wired Glucose Biosensors.

Glucose sensing has been studied for more than half a century, leading many to believe that further progress comes mainly from engineering efforts. Our society requires robust, reliable, compact, and easy-to-use sensing solutions for decentralized applications such as wearables, and engineering solutions are essential. However, true progress is only possible by understanding and improving the underlying working principles and fundamental limitations. This Perspective discusses the delicate relationship between the observed current and glucose concentration when using wired enzyme biosensors. Some of the potential pitfalls often encountered in the recent literature are discussed. These include the need to suppress the influence of enzyme turnover kinetics on the sensor signal and the undesired faradaic charging of the electron transfer mediator that gives a continuously decaying baseline signal. These fundamental issues must be carefully evaluated and resolved for the realization of continuously operating enzyme biosensor systems.

Nitric Oxide As a Signaling Molecule for Biofilm Formation and Dispersal in Mediated Electron Transfer Microbial Electrochemical Systems

With applications in bioremediation, biosensing, and bioenergy, microbial electrochemical systems are a rapidly growing, multidisciplinary field within biological, chemical, and materials science. Since these systems use living microorganisms as biocatalysts, it is important to understand how microbial physiology, namely biofilm formation, affects these electrochemical systems. Specifically, the literature lacks research that assesses the effects of biofilm on metabolic current output in mediated electron transfer systems. In this study, Rhodobacter capsulatus and Pseudomonas putida GPo1 were used as model, nonpathogenic strains that facilitate electron transfer via diffusible redox mediators. Nitric oxide has gained attention in biomedicine as a gaseous signaling molecule, which at sublethal concentrations may either augment or inhibit biofilm formation depending on the bacterial species. In R. capsulatus, nitric oxide treatment was associated with increased current yield and improved biofilm formation. However, in P. putida GPo1, nitric oxide treatment corresponded to significantly reduced current output, as well as biofilm dispersal. In addition to highlighting the use of electrochemical tools to assess the effects of nitric oxide in biofilm formation, these findings demonstrate that biofilm-based mediated electron transfer systems benefit from the increased electrochemical output and enhanced cell adhesion, which is promising for more robust applications compared to their planktonic counterparts. Figure 1

Parallel Amperometric and Potentiometric Multianalyte Detection in a Microfluidic System

The adoption of microfluidic technologies in electrochemical biosensor development has enabled quantitative biomarker monitoring that use significantly lower volumes of reagents and samples, miniaturized electrodes, and inexpensive fabrication techniques, while presenting opportunities for multianalyte detection. We describe the fabrication of amperometric and potentiometric biosensors on a multichannel, platinum screen-printed electrode (SPE) and demonstrate their operation in parallel on a microfluidic multianalyte electrochemical sensor array (µMESA) platform.Working electrodes (WEs) of an SPE were were modified with either enzymes or ion selective membranes (ISMs) for amperometric or potentiometric measurements respectively. Oxidase enzymes were dissolved in an osmium (II) bis(2,2'-bipyridine)chloride-poly(vinylimidazole-allylamine) redox polymer and immobilized on four WEs. The use of this osmium-based electron transfer mediator has been previously reported to lower the oxidation potential of analytes and to improve overall sensor performance. The remaining four WEs were modified by electrodeposition of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), an intrinsically conductive polymer. Solid contact ISMs were prepared by combining ionophores, lipophilic ion exchangers, and a fluorosilicone polymer, and drop casting the mixtures on PEDOT:PSS-coated WEs. Plasticizer-free ISMs improve sensor lifetime by lowering the glass transition temperature and eliminating leaching of plasticizers from the ISM. By utilizing these strategies, we fabricated amperometric sensors for glucose and lactate, and potentiometric sensors for K+ and Ca2+ ions. Glucose is a primary substrate for energy metabolism while lactate is a major metabolite and signaling molecule. K+ ions maintain cell membrane physiology and homeostasis whereas Ca2+ ions serve as messengers during muscle activity and neurotransmission.Sensor characteristics like sensitivity, selectivity, linear range, and operational longevity for each biosensor were assessed using chronoamperometry or chronopotentiometry techniques on a potentiostat/potentiometer instrument. The results indicate that the sensor fabrication strategies described, in combination with our µMESA platform, can be used to measure changes in metabolite concentrations under laminar flow. Ultimately, this versatile technology may provide novel insights into complex physiological and pathological processes in biological systems.

Recent Investigations on the Use of Copper Complexes as Molecular Materials for Dye-Sensitized Solar Cells.

Three decades ago, dye-sensitized solar cells (DSSCs) emerged as a route for harnessing the sun's energy and converting it into electricity. Since then, an impressive amount of work has been devoted to improving the global photovoltaic efficiency of DSSCs, trying to optimize all components of the device. Up to now, the best efficiencies have usually been reached with ruthenium(II) photosensitizers, even if in the last few years many classes of organic compounds have shown record efficiencies. However, the future of DSSCs is stringently connected to the research and development of cheaper materials; in particular, the replacement of rare metals with abundant ones is an important topic in view of the long-term sustainability of DSSCs intended to replace the consolidated fossil-based technology. In this context, copper is a valid candidate, being both an alternative to ruthenium in the fabrication of photosensitizers and a material able to replace the common triiodide/iodide redox couple. Thus, recently, some research papers have confirmed the great potential of copper(I) coordination complexes as a cheap and convenient alternative to ruthenium dyes. Similarly, the use of copper compounds as electron transfer mediators for DSSCs can be an excellent way to solve the problems related to the more common I3-/I- redox couple. The goal of this mini-review is to report on the latest research devoted to the use of versatile copper complexes as photosensitizers and electron shuttles in DSSCs. The coverage, from 2022 up to now, illustrates the most recent studies on dye-sensitized solar cells based on copper complexes as molecular materials.

Electrochemical microfluidic paper-based analytical device for label-free detection of SARS-CoV-2 antigen by LDH redox probe

In the offered study, the proposed sensor combined the innovative disposable microfluidic paper-based immunosensor and cost-effective plant-based anti-SARS-CoV-2 monoclonal antibody CR3022, expressed in Nicotiana benthamiana. An electrochemical microfluidic paper-based analytical device (µPAD) was introduced for quantitative detection of the SARS-CoV-2 antigen employing electrocatalytic activity of the Ni Fe layered double hydroxide (NiFe LDH). Its electrocatalytic activity asthe platform of proposed the analytical device enhanced the signal output via redox-recycling of the species the ferri/ferrocyanide [Fe(CN)6]3-/4- in solution and is applied to µPAD response signal. Layered NiFe double hydroxide (LDH) nanosheets with a suitable redox potential were prepared by incorporating Fe into the Ni-based LDH. With the help of Fe, the charge-transfer kinetics for the reduction of Ni3+ to Ni2+ was improved and the formation of unwanted Ni components with higher oxidation state was suppressed. The incorporated Fe as the electron transfer mediator enhanced the process of Ni(OH)2/NiOOH redox cycle. Under the optimum conditions, the dependency of impedance signal and SARS-CoV-2 concentration showed a linear region from 10 fg/mL-5 ng/mL with a detection limit of 0.23 fg/mL. This Paper-based immunosensor device also showed long stability and good reproducibility, which can be used for the quantitative assay of the SARS-CoV-2. The results of nasal samples analysis revealed the applicability of the resulting biosensor.

Corrosion of Pseudomonas aeruginosa toward a Cu-Zn-Ni alloy inhibited by the simulative tidal region.

The corrosion of marine engineering equipment not only threatens human security and ecological environment but also increases energy consumption, restricting the sustainable development of marine economies and industries. The tidal region is a complex and challenging environment that can cause severe corrosion of facilities and affect microbial activities. However, the current understanding of the mechanisms underlying microbiologically influenced corrosion (MIC) of tidal region is insufficient. To address this issue, the effect of Pseudomonas aeruginosa on a Cu-Zn-Ni alloy in the simulative tidal region was investigated by chemical and molecular biological analysis in this study. The results demonstrated that P. aeruginosa formed thicker biofilms on the Cu-Zn-Ni alloy samples under the full exposure, accelerating corrosion compared to sterile controls. Interestingly, the corrosion of P. aeruginosa toward the Cu-Zn-Ni alloy was inhibited in the simulative tidal region. This inhibition behavior was relevant to the reduction in the quantity of sessile cells and cell activities. The expression down-regulation of genes encoding phenazines induced the decrease in electron transfer mediators and weakened the MIC of P. aeruginosa on alloy samples in the simulative tidal region. The research sheds light on the characteristics of P. aeruginosa and corrosion products on the Cu-Zn-Ni alloy, as well as their interaction mechanisms underlying corrosion in the simulative tidal region. The study will facilitate the evaluation and control of MIC in the tidal region, contributing to the development of sustainable strategies for preserving the integrity and safety of marine facilities.

Development of novel Ce doped ZnO/graphene based sensor for electrochemical investigation of potassium-competitive acid blocker: Vonoprazan

The present study reports the synthesis of a Ce-doped ZnO/r-GO nanocomposite via a conventional hydrothermal route. The synthesized nanocomposites were utilized for the purpose of sensitive and selective detection of vonoprazan (VPN). The composite’s morphological, structural, and electrochemical properties were thoroughly characterized. This study focuses on the utilization of a glassy carbon electrode that has been modified with Ce-doped ZnO/r-GO for the purpose of detecting the potassium-competitive acid blocker VPN, which is commonly used in the treatment of peptic ulcer. The detection methods employed in this study include voltammetric and square wave techniques. The composite material exhibited exceptional efficacy as an electron (e−) transfer mediator during the oxidation of VPN. The modified electrode exhibited a discernible reaction for SWV assessments in relation to VPN identification, achieving a minimal detection threshold of 1.8 × 10−8M and an extensive range of linearity spanning from 2.0 × 10−7 M to 8.0 × 10−6 M, given ideal circumstances. The rate constant for charge transfer (ks) was determined to be 1.17 × 10−6 cm s−1, and an estimation of the electrochemical active surface area yielded a value of 0.081 cm2. The sensor that was artificially created demonstrated favorable selectivity, enduring stability, and notable reproducibility. The sensor has been utilized for the purpose of analyzing human serum and urine samples, yielding favorable recovery outcomes.