Ballast water (BW) is a major pathway for the spread of invasive microorganisms and pathogens, posing significant ecological and public health risks. The International Maritime Organization (IMO) has established strict discharge standards, yet routine monitoring remains limited, and no reliable onboard test is currently available to assist crews in verifying BW quality before discharge. This study presents the development of a rapid, portable method for onboard microbiological assessment of BW, based on potentiometric detection and biosensors engineered with the Bioelectric Recognition Assay (BERA). Two complementary approaches were evaluated: (i) direct potentiometric measurements of contaminated and non-contaminated samples, which confirmed the feasibility of detecting microbial presence but were restricted by high detection limits, and (ii) development of biosensors specifically engineered for Escherichia coli and Enterococcus spp. to improve specificity and lower the limit of detection (LOD). Results demonstrated successful detection of both microorganisms, with performance characteristics of 83.3% sensitivity and 81.9% accuracy for Enterococcus spp. (LOD: 102 CFU 100 mL−1), and 89.8% sensitivity and 85.1% accuracy for Escherichia coli (LOD: 250 CFU 100 mL−1). These findings underscore the potential of biosensor-based systems as practical, crew-operated tools for early warning and real-time monitoring of ballast water quality, supporting compliance with IMO standards and contributing to safer, more sustainable maritime operations.

Design and development of ISFET-based portable microalgal biosensor using Chlorella sp. for the detection of organophosphorus pesticide.

Exploration of a polymer responsive potentiometric biosensor for the detection of flagella and whole cell of Proteus mirabilis: proof-of-concept

The paper investigates the possibility of application of potentiometric biosensor based on creatinine deiminase for non-invasive analysis of creatinine in urine, sweat and saliva. The effect on the signal of various substances that can potentially affect the biosensor response and are contained in the urine of healthy people or patients with kidney diseases has been studied. It was shown that the contribution of these components to the total signal is minimal and will not significantly affect the accuracy of biosensor measurements. The stability during storage of the biosensor was more than 120 days. The principle possibility of creatinine determination by using a biosensor based on creatinine deiminase in saliva and sweat was shown, while the lowest creatinine concentration that can be determined was 50 μM. The developed biosensor demonstrates certain advantages in determining creatinine concentration in urine samples compared to the traditional colorimetric Jaffe method, which requires expensive equipment and careful control of reaction parameters to reduce the influence of interfering substances, as well as a complex measurement procedure.

In vivo electrochemical biosensors (IVEBs) have emerged as pivotal tools in advancing personalized healthcare paradigms, particularly due to their exceptional capability for real-time tracking of dynamic physiological biomarkers. Their seamless integration into next-generation health monitoring platforms has not only revolutionized clinical diagnostics but also propelled the innovation of implantable sensing architectures, thereby redefining precision medicine strategies through continuous in situ bioanalytical measurements. This review highlights the latest advancements of IVEBs, including potentiometric, amperometric, and impedance biosensors, emphasizing their high sensitivity, specificity, and capability to function in complex biological environments. Additionally, this review discusses the limitations of current IVEBs, such as sensitivity, miniaturization, and applications of biodiversity. In future, researchers should use novel biocompatible nanomaterials and artificial intelligence algorithms to promote the development of IVEBs.

The work presents a simulation of the kinetics of the responses of a potentiometric biosensor based on a differential pH-sensitive field-effect transistor (pH-FET) for the determination of creatinine using a bioselective element – the enzyme creatine deiminase. The modeling took into account such characteristics of the pH-FET as the threshold voltage and steepness of the transient I-V characteristic of the transistor, the composition and density of functional groups on the surface of the two-layer gate dielectric silicon oxide-nitride. The evolution of the change in the pH value of the solution near the transistor surface in response to the introduction of creatinine and the corresponding kinetics of the biosensor response are shown. The effect of enzyme immobilization in the PVA-SbQ photopolymer matrix on the enzyme concentration in the bioselective membrane is considered and the effect of the ionic strength of the buffer solution on the biosensor response is theoretically investigated. The obtained model results were compared with the experimental responses of the pH-FET of the creatinine biosensor in the range of substrate concentrations of 1-10 mM and their good correspondence was shown. The average modeling error was no more than 2% of the response value to the addition of 1 mM creatinine. It was shown that the calculated sensitivity values of the considered pH-FETs are in the range of 35-40 mV/pH for the working pH values of the solution, which corresponds to real sensor samples.

Next-generation electrochemical biosensors for acrylamide: Progress, challenges, and opportunities.

Preparation of a Nonenzymatic Potentiometric Lactic Acid Biosensor Modified by g-C₃N₄/ZnS Composite Materials on a SnO₂-Coated Flexible Printed Circuit Board

Development of a Nonenzymatic Potentiometric or Amperometric Lactate Biosensor Enhanced by Silver Phosphate/Titanium Dioxide on Flexible Printed Circuit Board

A kinetic framework is introduced for a pseudocapacitive potentiometric biosensor. Mathematical derivation and kinetic modeling demonstrate that experimentally observed linearity in analyte-OCP response arises from a dynamic equilibrium between competing redox reactions on a single electrode. This system can be expanded to develop a new generation of biosensors.

The spectrum pattern analysis of the urease enzyme immobilization technique in PVA, a PVA polymer that is soluble in warm water, has been carried out. There are differences in the spectrum patterns of PVA, PVA-KTpClPB and PVAEnzyme-KTpClPB solutions, respectively UVA, UVB and UVC. The purpose of this study was to create a cholesterol sensor whose analyte cholesterol on the indicator electrode was coated with a PVA-Enzyme cholesterol (ChOx)/GA 2.9%/PANI-p-toluenesulfonic acid/PVC-KTpClPB-o-NPOE 61% membrane. The method used is the potentiometric biosensor method of ChOx enzyme immobilization technique in PVA, which is symbolized by (PVA-E ChOx). This study was conducted by comparing the indicator electrode membrane coated with PVA- variation of Enzyme cholesterol (ChOx)/GA 2.9%/PANI-benzenesulfonic acid/PVC-KTpClPB-o-NPOE 61%. ChOx enzyme was varied at 1:1 and 1:3. The results of the UV-Vis analysis of ChOx enzyme immobilization in PVA obtained a spectrum pattern that was the same as the ChOx spectrum pattern on the ChOx enzyme 1:1. After obtaining the best results from the PVA-E ChOx membrane at 1:1. Continued coating of the first indicator electrode GA 2.9% / PANI-ptoluenesulfonic acid / PVC-KTpClPB-o-NPOE 61%. The second electrode GA 2.9% / PANI-benzenesulfonic acid / PVC-KTpClPB-o-NPOE 61%. Both membranes were analyzed by EDX, XRD, and FTIR, each placed on a tungsten wire and glass preparation, to determine the best membrane. The best membrane is PVA-E1 ChOx / GA 2.9% / PANIp-toluenesulfonic acid / PVC-KTpClPB-o-NPOE 61%.

The development of ultrasensitive electronic sensors for in vitro diagnostics is essential for the reliable monitoring of asymptomatic individuals before illness proliferation or progression. These platforms are increasingly valued for their potential to enable timely diagnosis and swift prognosis of infectious or progressive diseases. Typically, the responses from these analytical tools are recorded as digital signals, with electronic data offering simpler processing compared to spectral and optical data. However, preprocessing electronic data from potentiometric biosensor arrays is still in its infancy compared to more established optical technologies. This study utilized the Single-Molecule with a Large Transistor (SiMoT) array, which has achieved a Technology Readiness Level of 5, to explore the impact of data preprocessing on electronic biosensor outcomes. A dataset consisting of plasma and cyst fluid samples from 37 patients with pancreatic precursor cyst lesions was analyzed. The findings revealed that standard signal preprocessing can produce misleading conclusions due to artifacts introduced by mathematical transformations. The study offers strategies to mitigate these effects, ensuring that data interpretation remains accurate and reflective of the underlying biochemical information in the samples.

Nowadays, using a potentiometric ion sensor to achieve detection of biological analytes is still a big challenge, since these analytes usually do not yield a measurable ion signal. To address this challenge, a simple and robust potentiometric sensing protocol based on a delayed Nernstian response is proposed for the label-free detection of biological analytes. The proposed sensor platform is composed of two layers: the surface recognition layer and the indicator-ion-selective electrode (ISE) membrane layer. It is based on a surface blocking mechanism in which the surface recognition interactions between the surface recognition element and the target can impede the diffusion of the indicator ion from the aqueous phase to the sensing membrane phase to reach the final Nernstian-response equilibrium, thus resulting in a delayed potential change. Such a potential change could be used to measure the concentration of a biological target in the sample. Thus, a sensing system was designed by using phage MS2, its host bacterium Escherichia coli ATCC 15597(abbreviated as E. coli H), and a solid-contact butyrylcholine ISE as a surface recognition element, a target, and an indicator electrode, respectively. This new concept offers a simple, sensitive, and extremely selective potentiometric method for detection of E. coli H with a detection limit of 100 CFU mL-1. It can be expected that the present approach may pave the way to using ISEs to detect various important nonionic biological targets in clinical and environmental applications.

Nonlinear effects of partitioning and diffusion limitation on the efficiency of three-layer enzyme bioreactors and potentiometric biosensors

The main analytical characteristics of the potentiometric biosensor based on creatinine deiminase were investigated when working with model samples, and comparison for various enzyme immobilization methods was made. It was found that all sensors are characterized by a similar operating range, response time and high operational stability. At the same time, the sensitivity of the biosensor to creatinine was 2 times higher for the option of immobilization in a drop of glutaraldehyde. Storage stability was high for all immobilization methods, with the exception of immobilization in glutaraldehyde vapors, when the value of the sensor response dropped by 50% after 100 days of storage. The dependences on the experimental conditions were typical for enzyme biosensors and did not depend on the enzyme immobilization method. The linear range of creatinine determination is quite suitable for further work with real blood samples and dialysis fluid when diluted 10 times.

Enzyme-based amperometric biosensors have become popular for healthcare applications. However, they have been under constant pressure for technological innovation to improve their sensitivity and usability. An ideal biosensor has high sensitivity and calibration-free characteristics. This study aims to report enzyme-based glucose and lactate sensors that utilize a proposed "time-derivative of potential (dOCP/dt)" method, with a further aim being to prove theoretically and experimentally that dOCP/dt values are proportional to substrate concentration. High sensitivity is obtained regardless of the electrode size because the electrode potential is independent of the electrode area in the biosensor. Importantly, because the substrate diffusion determines the enzyme reaction rate on the sensors, the dOCP/dt biosensors can essentially eliminate external influences such as temperature and pH. The result is the successful realization of a biosensor that is calibration-free, making it a much more practical option.

Cardiovascular diseases are the number one cause of death worldwide, with Heart Failure (HF) accounting for a third of these fatalities. Therefore, there is a growing need for a point-of-care (POC) device capable of providing timely and accurate information on HF to minimize its impact on patients. N-terminal pro-B-type natriuretic peptide (NT-proBNP), released by myocardial cells in the blood in response to stress or strain, is regarded as the gold standard biomarker for HF management given its superior clinical relevance in diagnosis, prognosis, and therapy. Electrochemical potentiometric biosensors are promising alternatives to traditional analytical methods for biomarker detection. In particular, organic electrochemical transistors (OECTs) have garnered increased attention due to their ability to interface bodily fluids by simply operating inside an ionic environment. Additionally, they possess inherent transistor-specific amplification capabilities represented by the transconductance (gm), shown to scale with the thickness of the semiconducting channel, yielding values that are orders of magnitudes higher than those of field effect transistors (FETs). This feature enables OECTs to detect and amplify the presence of the target molecule without relying on complementary methodologies.HF patients lack self-operated and reliable POC devices that can provide immediate information about their health ensuring clinical accuracy for diagnosis and intervention. While several methods have been proposed, they fail to combine self-operation, speed, low-cost, and clinical accuracy. In this work, we aim to develop a POC HF sensor that can detect and quantify NT-proBNP levels in a finger prick blood volume, all while being cheap to fabricate, easy to operate, and rapid in providing results.OECTs were fabricated using inkjet-printing. First, the source, drain, and gate (2.5x2.5 mm) were patterned using a conductive gold nanoparticle ink. Subsequently the leads were insulated with polyimide, after which PEDOT:PSS was deposited to form the semi-conducting channel (15x400µm). Antibody immobilization for NT-proBNP detection was achieved by chemical functionalization of either the channel or the gate. To functionalize the channel, the PEDOT:PSS surface was treated with oxygen plasma to introduce hydroxyl groups. The following steps included silanization, then streptavidin grafting by immersion, and finally, antibody immobilization using biotinylated anti-NT-proBNP antibodies. To functionalize the gate, a quick three step protocol was adapted by employing thiolated-biotinylated-Polyethylene Glycol followed by streptavidin and then biotinylated antibodies. Surface functionalization, in both cases, was verified using electrochemical impedance spectroscopy (EIS). To detect the presence and quantify the levels of NT-proBNP using the realized OECT, several concentrations of NT-proBNP were prepared in PBS and tris-base buffer (pH=8.5) and introduced into the device sensing area. The different concentrations were distinguished through scanning of the transfer characteristic at drain-source voltages (VDS)=-0.05V or -0.5V and gate-source voltages (VGS)=0 to 0.8V.The developed biosensor has a miniaturized active recording area, enabling the use of minimal volumes to operate and detect NT-proBNP. The functionalization of either the in-plane gold gate or the PEDOT:PSS channel was validated by an increase in the electric impedance of the system at every step. Repetitive transfer characteristics scans revealed better stability at -0.05 VDS compared to -0.5 VDS, which is attributed to decreased channel current, and subsequently, preserved channel integrity in solution at the lower bias. The latter increases channel stability, but decreases gm, yet remains sufficiently high to successfully detect NT-proBNP at clinically relevant concentrations (0 to 1000 pg/ml). Functionalizing the gate led to a linearity of 95%, and a decrease in variability across trials compared to functionalizing the channel which can be attributed to the smaller detection area and better reactivity. The sensor also demonstrated selectivity by exhibiting a stronger response to NT-proBNP compared to BSA (a non-specific protein) proving the effectiveness of the chemical functionalization, which is particularly important when using the sensor with a complex solution like blood.In this work, we have developed an electrochemical potentiometric solution towards HF POC applications, capable of quantifying NT-proBNP in microvolumes at clinically relevant concentrations with high sensitivity, specificity, and repeatability. The adapted microfabrication methodology provides a cheap and quick approach for producing high performing sensors, rendered sensitive to HF biomarkers by chemical modification. The functionalization was found to be efficient and faster when applied at the gate instead of the channel given the versatile nature of the in-plane gate and the size-dependent performance limitations of the channel. The successful bedside integration of such technology holds promise in reducing HF mortality by enabling early diagnosis and immediate intervention, improving disease progression and management, and facilitating personalized strategies for prognosis, therapy, and prevention.

Potentiometry based on ion-selective electrodes (ISEs) has undergone a renaissance with improvements in the detection limits and selectivities of ISEs, the introduction of new materials, new sensing concepts (from conventional potentiometry to dynamic electrochemistry approaches), and deeper theoretical understanding and modelling of the potentiometric responses of ISEs. The most recent innovations support improvements in software for ion sensing and biosensing. Additionally, adaptable sensing techniques have been created for a wide range of various target molecules, including enzymes, antibodies, aptamers, and peptides, in response to the introduction of new receptors by using ISEs as powerful transducers. Current potentiometric biosensor trends are examined in this paper. Their applications in the biosensing of metal ions, small molecules, DNA, proteins, microorganisms, and poisons have been discussed. This review provides a forecast for potentiometric biosensing based on the integration of potentiometric ISEs with innovative materials and cutting-edge techniques.

Charged antimicrobial peptides can be used for direct potentiometric biosensing, but have never been explored. We report here a galvanostatically-controlled potentiometric sensor for antimicrobial peptide-based biosensing. Solid-state pulsed galvanostatic sensors that showed excellent stability under continuous galvanostatic polarization were prepared by utilizing reduced graphene oxide/poly (3,4-ethylenedioxythiophene): poly (4-styrenesulfonate) (rGO/PEDOT: PSS) as a solid contact. More importantly, the chronopotentiometric sensor can be made sensitive to antimicrobial peptides with intrinsic charge on demand via a current pulse. In this study, a positively charged antimicrobial peptide that can bind to Staphylococcus aureus with high affinity and good selectivity was designed as a model. Two arginine residues with positive charges were linked to the C-terminal of the peptide sequence to increase its potentiometric responses on the electrode. The bacteria binding-induced charge or charge density change of the antimicrobial peptide enables the direct chronopotentiometric detection of the target. Under the optimized conditions, the concentration of Staphylococcus aureus can be determined in the linear range 10-1.0×105 CFU mL-1 with a detection limit of 10 CFU mL-1. It is anticipated that such a chronopotentiometric sensing platform is readily adaptable to detect other bacteria by choosing the peptides.

The influence of charge on the translation of the sandwich ELISA approach to electronic biosensors