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Bacterial pathogens are responsible for a variety of human diseases, necessitating their prompt detection for effective diagnosis and treatment of infectious diseases. Over recent years, electrochemical methods have gained significant attention owing to their exceptional sensitivity and rapidity. This review outlines the current landscape of electrochemical biosensors employed in clinical diagnostics for the detection of bacterial pathogens. We categorize these biosensors into four types: amperometry, potentiometry, electrochemical impedance spectroscopy, and conductometry, targeting various bacterial components, including toxins, virulence factors, metabolic activity, and events related to bacterial adhesion and invasion. We discuss the merits and challenges associated with electrochemical methods, underscoring their rapid response, high sensitivity, and specificity, while acknowledging the necessity for skilled operators and potential interference from biological and environmental factors. Furthermore, we examine future prospects and potential applications of electrochemical biosensors in clinical diagnostics. While electrochemical biosensors offer a promising avenue for detecting bacterial pathogens, further research in optimizing the robustness and surmounting the challenges hindering their seamless integration into clinical practice is imperative. [ABSTRACT FROM AUTHOR]

This article explores the advancements and future prospects of biosensors, which are devices used for monitoring healthcare, environmental safety, and food quality. It discusses the history and evolution of biosensors, emphasizing the need for sustainable and environmentally friendly options. The article also mentions the potential of additive manufacturing techniques and the integration of biosensors with IoT technology and machine learning. It provides valuable insights into the current state and future directions of biosensor technology. Additionally, the document includes references to scientific articles and books on related topics, such as achieving net-zero emissions in global food systems and wearable sensors for personalized predictions of clinical laboratory measurements. [Extracted from the article]

A wearable bioelectronic ion sensing device has been proposed based on the mixed electronic-ionic conductors of tungsten bronzes. The sensor features no requirement of organic ion selective membranes (ISM) for the ion recognition. This ISM-free characteristic offers the possibility for the next generation of solid ion sensor for biological applications. [Display omitted] Noninvasive and continuous monitoring of electrolytes in biofluids based on wearable biotechnology provides extensive health-related physiological information. The state-of-the-art wearable bioelectronic ion sensors depend on the organic ionophore-based solid-contact structure of potentiometric ion-selective electrodes. This structure contains two functional sensing layers, i.e., a solid contact (ion-to-electron signal transduction) and an ionophore-containing ion-selective membrane (ISM, ion recognition). However, the potential drift, biotoxicity, and expensive organic ionophores complicate practical wearable applications. These challenges intrinsically originate from the ISM. Herein, an ISM-free wearable ion sensor based on mixed electronic-ionic conductors of tungsten bronzes is reported. These materials can serve as a bifunctional sensing layer for simultaneous ion-to-electron transduction through the redox reaction of W6+/5+ and ion recognition through crystal ion exchange. The K- and Na-adjusted WO 3 disclosed Nernstian responses toward NH 4 + and H+, respectively. The selectivity is comparable to or even better than organic ionophores, such as ammonia ionophore of nonactin. Further, the on-body monitoring of sweat ammonia and pH was realized using an integrated ISM-free flexible sensor. Therefore, this work offers an ISM-free concept and emphasizes the importance of developing next-generation ISM-free wearable bioelectronic ion sensors. [ABSTRACT FROM AUTHOR]

A bioselective membrane of the potentiometric sensor based on butyrylcholinesterase and pH-sensitive field-effect transistors (FETs) modified with gold nanoparticles (GNPs) have been developed. In the present investigation, we focused on the study and adjustment of the potentiometric biosensor just for the case of using gold nanoparticles because butyrylcholinesterase has been already used to create the sensors for determination of organophosphorus/carbamate pesticides, heavy metals and glycoalkaloids. The composition of a butyrylcholinesterase-based bioselective membrane with gold nanoparticles was optimized. An influence of the parameters of a work solution on analytical characteristics of biosensor was comprehensively investigated and thoroughly analyzed. An increase of biosensor responses and sensitivity as a result of using GNPs was shown. A highly sensitive, selective biosensor based on immobilized butyrylcholinesterase was developed; its laboratory prototype has linear range of 0.025–0.2 mM, minimum limit of detection of 0.018 mM; response time of 1.4 min. Thus, application of the bioselective membrane modified with gold nanoparticles opens new possibilities to create a new electrochemical biosensors with high sensitivity and stability. [ABSTRACT FROM AUTHOR]

A potentiometric sensor as a selective, straightforward, and sensitive device was prepared based on a carbon paste electrode (CPE) as an indicator electrode for determining manganese (II) ions in environmental water and biological samples. A novel and synthetic ligand, 5,5'-((2E,2'E)-2,2'-(1,2-diphenylethane-1,2-diylidene)bis(hydrazin-1-yl-2-ylidene))bis (4-amino-4H-1,2,4-triazole-3-thiol) (called BBP), which has a selective interaction with Mn2+ ion, was chosen as an ionophore in the CPE composite. An optimal mixture design was generated to optimize the CPE components' percentages, including BBP, MWCNTs, an ionic liquid, and graphite powder, and to investigate binary interactions between the component amounts. Effects of several modifier agents, such as MWCNTs, NH2-MWCNTs, and COOHMWCNTs, were evaluated in the CPE composite. The ability of two binders (Paraffin oil and an ionic liquid ([Bmim][BF4])) in the CPE composite was compared, indicating that ionic liquid has a better response than paraffin oil due to an increase in electrical conductivity and flexibility of CPE. Under the CPE components optimization, the sensor displayed a wide pH range from 2.8 to 8.2, a short response time (5 s), and a long lifetime (11 weeks) for the Mn2+ ion determination. The sensor also has a wide linear range from 1.0×10-7-1.0×10-1 M with a LOD of 3.1×10-8 M and an R-squared of 0.998 without significant interfering effects of other ions for the Mn2+ ion measurement. The sensor performance was studied by analyzing river water, well water, and human urine samples, and the results were compared with flame atomic absorption spectrometry. [ABSTRACT FROM AUTHOR]

The amalgamation of flexible electronics in biological systems has shaped the way health and medicine are administered. The growing field of flexible electrochemical bioelectronics enables the in situ quantification of a variety of chemical constituents present in the human body and holds great promise for personalized health monitoring owing to its unique advantages such as inherent wearability, high sensitivity, high selectivity, and low cost. It represents a promising alternative to probe biomarkers in the human body in a simpler method compared to conventional instrumental analytical techniques. Various bioanalytical technologies are employed in flexible electrochemical bioelectronics, including ion-selective potentiometry, enzymatic amperometry, potential sweep voltammetry, field-effect transistors, affinity-based biosensing, as well as biofuel cells. Recent key innovations in flexible electrochemical bioelectronics from electrochemical sensing modalities, materials, systems, fabrication, to applications are summarized and highlighted. The challenges and opportunities in this field moving forward toward future preventive and personalized medicine devices are also discussed.

Nanowire or nanobelt sensors based on silicon-on-insulator field-effect transistors (SOI-FETs) are one of the leading directions of label-free biosensors. An essential issue in this device construction type is obtaining reproducible results from electrochemical measurements. It is affected by many factors, including the measuring solution and the design parameters of the sensor. The biosensor surface should be charged minimally for the highest sensitivity and maximum effect from interaction with other charged molecules. Therefore, the pH value should be chosen so that the surface has a minimum charge. Here, we studied the SOI-FET sensor containing 12 nanobelt elements concatenated on a single substrate. Two types of sensing elements of similar design and different widths (0.2 or 3 μm) were located in the chips. The drain-gate measurements of wires with a width of 3 µm are sufficiently reproducible for the entire chip to obtain measurement statistics in air and deionized water. For the pH values from 3 to 12, we found significant changes in source-drain characteristics of nanobelts, which reach the plateau at pH values of 7 and higher. High pH sensitivity (ca. 1500 and 970 mV/pH) was observed in sensors of 3 μm and 0.2 μm in width in the range of pH values from 3 to 7. We found a higher "on" current to "off" current ratio for wide wires. At all studied pH values, Ion/Ioff was up to 4600 and 30,800 for 0.2 and 3 μm wires, respectively. In the scheme on the source-drain current measurements at fixed gate voltages, the highest sensitivity to the pH changes reaches a gate voltage of 13 and 19 V for 0.2 μm and 3 μm sensors, respectively. In summary, the most suitable is 3 μm nanobelt sensing elements for the reliable analysis of biomolecules and measurements at pH over 7. [ABSTRACT FROM AUTHOR]

Epilepsy is a chronic neurological disease and its treatment requires the use of anti-epileptic drugs. The determination of anti-epileptic drugs in pharmaceutical and biological samples is carried out using various analytical methods. Potentiometric methods, which have a very important place in electroanalytical chemistry, are used extensively in the determination of various drugs in biological and pharmaceutical samples. In this study, we reviewed potentiometry-based sensors developed for the determination of anti-epileptic drug molecules in biological and pharmaceutical samples. [ABSTRACT FROM AUTHOR]

Due to their effect on human health, rapid, sensitive, and accurate methods for detecting foodborne bacterial pathogens are becoming increasingly important. There are more than 250 types of bacterial foodborne disease, including more than 90% of outbreaks of foodborne illness worldwide, which is considered to be one of the greatest threats to public health. Among the diagnostic methods, electrochemical biosensors have features that make them very efficient in designing and manufacturing biosensors. Potentiometric biosensors have been recognized for their effectiveness in detecting analytes with low cost, ease of use, and simple instrumentation. This article reviews key advances in potentiometric biosensors of foodborne bacterial pathogens. The categorization of different potentiometric biosensors is done on the basis of various foodborne bacterial pathogens involving Escherichia coli, Staphylococcus aureus, Listeria monocytogenes, and Salmonella typhimurium. [ABSTRACT FROM AUTHOR]

Redox reactions in live cells are generated by involving various redox biomolecules for maintaining cell viability and functions. These qualities have been exploited in the development of clinical monitoring, diagnostic approaches, and numerous types of biosensors. Particularly, electrochemical biosensor-based live-cell detection technologies, such as electric cell–substrate impedance (ECIS), field-effect transistors (FETs), and potentiometric-based biosensors, are used for the electrochemical-based sensing of extracellular changes, genetic alterations, and redox reactions. In addition to the electrochemical biosensors for live-cell detection, cancer and stem cells may be immobilized on an electrode surface and evaluated electrochemically. Various nanomaterials and cell-friendly ligands are used to enhance the sensitivity of electrochemical biosensors. Here, we discuss recent advances in the use of electrochemical sensors for determining cell viability and function, which are essential for the practical application of these sensors as tools for pharmaceutical analysis and toxicity testing. We believe that this review will motivate researchers to enhance their efforts devoted to accelerating the development of electrochemical biosensors for future applications in the pharmaceutical industry and stem cell therapeutics. [ABSTRACT FROM AUTHOR]

• An overview of the potentiometric biosensors to determine urea in clinical samples. • Potentiometric urea biosensors were developed with various materials, methodologies. • We investigated and compared the performance characteristics of these biosensors. Excess nitrogen in the body is converted to urea in the liver, and urea is disposed as a waste product in urine. Urea concentration can change in body fluids such as blood due to the presence of certain disorders. Therefore, the determination of urea is of high importance in various areas including medical diagnosis, as well as food quality control and environmental monitoring. Potentiometric sensors have certain advantages over their alternatives, such as rapidity, portability, cost effectiveness, high sensitivity, easy operation and simple apparatus. Potentiometric urea biosensors based on enzyme urease have been developed using various materials including nanoparticles and films, and also using different methodologies. In this review, we covered potentiometric urea biosensors reported in the literature, and touched upon their certain structure characteristics and performance parameters including detection limit, working concentration range, response time and lifetime, all of which are of practical importance. Each potentiometric urea biosensor has its own advantages and drawbacks, thus the selection of appropriate method depends on the sample to be analyzed, its urea concentration range and other requirements of the particular application. Further research is needed in order to optimize the performance of these devices and to broaden their applicability. [ABSTRACT FROM AUTHOR]

Stability is one of the most important characteristics of the potentiometric urea biosensors; however, it has rarely been discussed in previous literature. In this article, the stability of the potentiometric urea biosensor based on the urease-Ag NPs/RuO2 sensing film was studied. Using the voltage–time ($V$ – $T$) measurement system, the stability was verified by analyzing the biosensor’s reproducibility, repeatability, long-term measurement, and effect of temperature. Based on the results of this study, the proposed potentiometric urea biosensor had good reproducibility [relative standard deviation (RSD) was 2.23%] and repeatability (RSD was 1.16%). The urease-Ag NPs/RuO2 sensing film still has 90% initial sensitivity after 15 days of storage at room temperature. Moreover, the proposed urea biosensor was integrated into the microfluidic system and the remote measurement system. The sensing characteristics of the potentiometric urea biosensor under different flow rates (1.4–7.0 $\mu \text{L}$ /min, 0–30 $\mu \text{L}$ /min) were studied. In the remote measurement, the average sensitivity was 45.75 mV/decade and the linearity was 0.986. [ABSTRACT FROM AUTHOR]

Thanks to rapid technological innovation over the last decade, a wide range of wearable devices have emerged, playing an inspiring role in healthcare, diagnostics, and sports monitoring. This review summarizes recent progress in the development and application of electrochemical (EC) sweat sensors and self-powered systems for wearable applications. Presented here are the most common types of EC sweat sensors, namely potentiometric ion-selective electrodes, amperometric enzymatic and non-enzymatic sensors, as well as differential pulse voltammetric sensors. The sensing principle and novel functional nanomaterials that are used to enhance the performance of wearable sweat sensors and their applications are summarized. The recent advancement of battery-free wearable devices is presented, including self-powered biofuel cells (BFC), energy harvesting from novel materials and its strategy, are also discussed. The challenges in, and opportunities for, the development of sweat sensor-based wearable systems moving forward are reviewed, with the aim of shedding some light on future directions. [ABSTRACT FROM AUTHOR]

The quick progress in health care technology as a recurrent measurement of biochemical factors such as blood components leads to advance development and growth in biosensor technology necessary for effectual patient concern. The review wok of authors present a concise information and brief discussion on the development made in the progress of potentiometric, field effect transistor, graphene, electrochemical, optical, polymeric, nanoparticles and nanocomposites based urea biosensors in the past two decades. The work of authors is also centred on different procedures/methods for detection of urea by using amperometric, potentiometric, conductometric and optical processes, where graphene, polymer etc. are utilised as an immobilised material for the fabrication of biosensors. Further, a comparative revision has been accomplished on various procedures of urea analysis using different materials‐based biosensors, and it discloses that electrochemical and potentiometric biosensor is the most promise one among all, in terms of rapid response time, extensive shelf life and resourceful design. [ABSTRACT FROM AUTHOR]

This paper reports on the electrochemical behavior of an ATP biosensor that utilizes glucose oxidase (GOx) and hexokinase (Hex) immobilized within the electroactive polymer, polyethylenedioxythiophene (PEDOT). This biosensor design detects ATP indirectly at 0.85 V vs. Ag/AgCl based on the oxidation current for enzymatically generated H2O2, and at −0.20 V; a potential at which improved analyte selectivity is achieved. The detection figures of merit at both detection potentials are a response time of 15±1 s, an experimental detection limit of 10.0±0.2 μmol L−1 (S/N=3), and a sensitivity in the range of 100–500 mA M−1cm−2. [ABSTRACT FROM AUTHOR]

We report here the concept of a magnetically controlled extraction of hydrophilic bioreceptors into polymeric membranes for bioassays. The potentiometric assay relies on the intrinsic charges of an antimicrobial peptide and its unique recognition abilities, which can eliminate the probe labeling and indicator addition. The target binding event could effectively prevent the extraction of the peptide into the polymeric membrane doped with an ion exchanger, thus resulting in a potential change. The potentiometric response properties of the peptide assembled on magnetic beads can be dynamically controlled and modulated by applying a magnetic field. Staphylococcus aureus, as a model of food‐borne pathogens, was measured at levels down to 10 CFU mL−1. Based on this sensing strategy, a potentiometric array was developed for the pattern recognition of bacteria. The proposed general platform can be used for potentiometric biosensing using other hydrophilic bioreceptors. [ABSTRACT FROM AUTHOR]

A filter paper sputtered with a layer of Pt and subsequently coated with a Nafion® membrane is used as working electrode. The mixed potential of the Pt electrode allows the detection of H2O2 generated by the oxidation of galactose in the presence of the galactose oxidase enzyme. This provides a simple and mediator‐free approach method. The system shows sensitivity values of −62.8±9.4 mV/decade of galactose in the range from 0.3 to 31.6 mM, well within the clinical relevant range. MnO2 nanoparticles were added to decrease the interference from ascorbic acid so that validation of the sensor in whole blood samples was performed with good recovery. [ABSTRACT FROM AUTHOR]

In this work, we used radio frequency (RF) system and screen printing technology to fabricate urea biosensor based on urease-maghemite nanoparticles (γ-Fe2O3 NPs)/graphene oxide (GO)/nickel oxide (NiO) sensing membrane on silver conductive wire printed polyethylene terephthalate (PET) substrate. The V – T measurement system was used to investigate the sensing characteristics of urea biosensors based on GO/NiO sensing membrane modified by γ-Fe2O3 NPs. The sensing membrane was modified by adding different contents of γ-Fe2O3 NPs. The concentration of γ-Fe2O3 NPs was 1 mg/mL. When the volume ratio of urease/γ-Fe2O3 NPs was 1/1, it had the best sensitivity. The average sensitivity, the linearity, and the limit of detection of (LOD) of the best urea biosensor in this work were 52.36 mV/decade ± 0.22 mV/decade, 0.996, and $7.91~μM, respectively. The effect of temperature on the urea biosensor was investigated from 25 °C to 65 °C. The stability of urea biosensors was evaluated by the effect of hysteresis and long-term storage stability. After 29 days, the average sensitivity remained 80.62% of the initial value. Compared with other urea biosensors, our urea biosensor based on urease-γ-Fe2O3 NPs/GO/NiO sensing membrane has better average sensitivity. [ABSTRACT FROM AUTHOR]

Cucurbiturils are macrocyclic molecules and have been used with promising results in the development of electrochemical sensors and biosensors due to their main properties such as shape, selectivity, binding interactions and solubility. However, its application for the development of ion selective electrodes has been scarce. In this work, cucurbit[6]uril was used as molecular‐recognition compound for etilefrine sensing membrane with potentiometric transduction. The etilefrine selective electrode was evaluated and proposed as an alternative methodology for pharmaceutical quality control. Different membranes composition were evaluated, considering the use of different solvent mediators and the presence of anionic additives. The best membrane comprises 9.24 mmol.Kg−1 of cucurbit[6]uril, 68.90 % (w/w) of dibutylsebacate and 30.18 % (w/w) of carboxylated polyvinyl chloride. The electrode exhibited selective cationic response toward the etilefrine in a concentration interval of more than four decades, with an slope of 57.4±0.5 mV dec−1, a practical detection limit of (8±1)×10−7 mol L−1 and a low limit of linear range of (1.25±0.28)×10−6 mol L−1. The selectivity of the electrode towards different interfering was high. A comparative evaluation of the accuracy and precision of both procedures was done using the t‐student test (t4,12=1.135) and the Fischer test (F12,4=2.42) and compared with the tabulated ones (t4,12=1.135, F11,3=5.91) for the level of confidence of 95 %. [ABSTRACT FROM AUTHOR]

Determination of Varicella vaccine's potency; containing live attenuated strain (Oka) of Varicella Zoster virus, has been limited to in vitro cell culture methods. In this study, a label free potentiometric biosensor has been developed for the first time and optimized to determine the content of varicella zoster virus. A passive ion-flux sensing platform has been developed using an anti-varicella monoclonal antibody and tetrabutyl ammonium bromide as a marker ion. The immunosensor has been optimized with respect to membrane diameter and concentration of the immobilized antibody. Linearity was achieved over a concentration range of 2.5–3.2 log PFU/dose with a LOD of 1.9 log PFU/dose. Potentiometric results were compared to the plaque-forming assay using the cell culture technique. The developed immunosensor was superior with respect to analysis time and cost without affecting critical analytical performance characteristics. Furthermore, in order to evaluate the stability indicating ability of the immunosensor, the effect of pH and temperature was investigated. Vaccine samples were subjected to forced degradation conditions; pH and elevated temperatures. Stability results showed the ability of immunosensor to differentiate between intact and degraded viral content. This would demonstrate the reliability of the immunosensor for evaluating the efficacy and stability of the vaccine. [Display omitted] • A label free potentiometric immunosensor was optimized to determine varicella zoster virus applying ion-flux approach. • Potentiometric results were found comparable to the results of the compendial cell based method. • The critical performance parameters of the biosensor were validated according to FDA guidelines. • Stability study demonstrated the ability of the immunosensor to differentiate between intact and degraded virus content. • The performed study illustrated the applicability of the immunosensor for quality control and batch release purposes. [ABSTRACT FROM AUTHOR]

We present a portable multiplexed biosensor platform based on the extended gate field-effect transistor and demonstrate its amplified response thanks to gold nanoparticle-based bioconjugates introduced as a part of the immunoassay. The platform comprises a disposable chip hosting an array of 32 extended gate electrodes, a readout module based on a single transistor operating in constant charge mode, and a multiplexer to scan sensing electrodes one-by-one. Although employing only off-the-shelf electronic components, our platform achieves sensitivities comparable to fully customized nanofabricated potentiometric sensors. In particular, it reaches a detection limit of 0.2 fM for the pure molecular assay when sensing horseradish peroxidase-linked secondary antibody (∼0.4 nM reached by standard microplate methods). Furthermore, with the gold nanoparticle bioconjugation format, we demonstrate ca. 5-fold amplification of the potentiometric response compared to a pure molecular assay, at the detection limit of 13.3 fM. Finally, we elaborate on the mechanism of this amplification and propose that nanoparticle-mediated disruption of the diffusion barrier layer is the main contributor to the potentiometric signal enhancement. These results show the great potential of our portable, sensitive, and cost-efficient biosensor for multidimensional diagnostics in the clinical and laboratory settings, including e.g., serological tests or pathogen screening. [Display omitted] • Electronic immunosensor platform constructed using only off-the-shelf components. • Platform enables highly reproducible spatially multiplexed biosensing. • Significantly lower limit of detection compared to the standard ELISA method. • Potentiometric signal amplification caused by gold nanoparticle/antibody conjugates. • Analysis of potentiometric signal amplification mechanism by impedance spectroscopy. [ABSTRACT FROM AUTHOR]

• Hemoglobin-I was covalently grafted to transparent mesoporous GLAD-ITO electrodes. • Covalent attachment leads to stable high surface area bio-functionalized electrodes. • Hb-I/GLAD-ITO allows fast, selective and reversible optical detection of H 2 S. • This versatile strategy paves the way to innovative opto-electrochemical (bio)sensors. Sensitive and selective detection of analytes in complex biological fluids can be an extremely challenging issue. The constructive association of biomolecules and transparent mesoporous electrodes is of interest in this area, as it can lead to innovative biosensors combining optical and electrochemical detection modes. This concept, however, requires the development of appropriate surface functionalization methodologies that are robust enough for long-term operation in physiological environments. In the present work, the high-surface area of 3D transparent mesoporous indium-tin oxide (ITO) electrodes (prepared by glancing angle deposition or GLAD) has been chemically functionalized with recombinant hemoglobin I from Lucina pectinata according to a versatile 2-step process. First, 4-diazoniumbenzoic acid salt is covalently electrografted onto the ITO surface, followed by amide coupling of the protein. The resulting electrodes were quantitatively characterized by cyclic voltammetry and UV–vis absorption spectroscopy, demonstrating high surface coverages (up to 45% of a closed-packed monolayer for Hemoglobin-I) and homogeneous distribution across the entire thickness of the GLAD mesoporous structure. Good stability is also observed when the modified electrodes are immersed for prolonged times in a high ionic strength saline buffer. We also show that the hemoglobin I-modified electrode can be used as an optical biosensor for the selective, reversible, and fast detection of H 2 S in aqueous solutions over a ∼two-decade concentration range (i.e. up to 10 μM) and with a limit of detection of 0.35 μM. Good analytical performance was also achieved in human plasma without significant interference from the biological matrix. [ABSTRACT FROM AUTHOR]

Abstract Nowadays, development of highly efficient potentiometric sensors attracts the attention of many researchers over the world; due to the great expansion of portable analytical devices. This study aims to apply a current development to the construction and sense of carbon paste sensors based on flowered-like Mg-Al layered double hydroxides/multiwalled carbon nanotubes (FLLDH/MWCNTs) (sensor І), FLLDH/titanate nanotubes (TNTs) (sensor ІІ) and MWCNTs/TNTs (sensor ІІІ) nanocomposites for bambuterol hydrochloride analysis; to enhance the potentiometric response towards determination of the drug. The sensors exhibited excellent Nernstian slopes 58.8 ± 0.5, 58.5 ± 0.8 and 57.4 ± 0.7 mV/decade with linear working ranges of 1.0 × 10−7–1.0 × 10−2, 1.0 × 10−6–1.0 × 10−2 and 1.0 × 10−7–1.0 × 10−2 mol L−1, detection limits 2.3 × 10−8, 2.5 × 10−7and 7.5 × 10−8 mol L−1 and quantification limits of 7.6 × 10−8, 8.3 × 10−7and 2.5 × 10−7 mol L−1 for sensor І, ІІ and ІІІ, respectively. The selectivity behaviour of the investigated sensors was tested against biologically important blood electrolytes (Na+, K+, Mg2+, Ca2+). The proposed analytical method was successfully applied for BAM determination in pure drug, pharmaceutical products, surface water, human plasma and urine samples with excellent recovery data (99.62, 99.10 and 98.95%) for the three sensors, respectively. Graphical abstract Unlabelled Image Highlights • Novel potentiometric sensors are fabricated based on FLLDH/MWCNTs, FLLDH/TNTs, MWCNTs/TNTs nanocomposites. • The selectivity behaviour of investigated sensors was examined and discussed. • The morphology and surface properties of sensors were characterized by FESEM, HRTEM and EIS. • Successful BAM determination in real water, plasma and human urine samples. [ABSTRACT FROM AUTHOR]

In this study, we showed proof-of-principle experiments to demonstrate a printed organic inverter-circuit-based enzyme sensor with an extended-gate electrode with a lactate oxidase (LOx) and Prussian Blue carbon-graphite ink active area for the first time to inform users of an L-lactate overlimit concentration via a simple integrated electrophoretic display. The twostage organic inverter circuit exhibited an abrupt shift in output voltage depending on the potentiometric sensor signal imposed on the constant input voltage of the inverter circuit, resulting in a distinct color change of the display connected to the output line of the inverter circuit. The L-lactate concentration limit was tuned by changing the input voltage of the inverter circuit. This new type of wearable biosensor, notifying the user of an overlimit condition, can arbitrarily be tuned by professionals such as medical doctors or sports trainers and would be helpful for users who do not have sufficient knowledge about the detected biomarkers. [ABSTRACT FROM AUTHOR]

A new wearable potentiometric tattoo biosensor for real-time on-body monitoring of G-type nerve agents simulant is described. The skin-worn flexible biosensor responds rapidly and selectively to the fluorine-containing organophosphates (OP) nerve agent simulant diisopropyl fluorophosphate (DFP, a model OP analyte) in both liquid and vapor phases. The epidermal potentiometric OP biosensor relies on the pH-sensitive polyaniline (PANi) coating on a flexible printed transducer for monitoring the proton release during the enzymatic hydrolysis of DFP by enzyme organophosphate hydrolase (OPH). The sensing electrodes are screen printed on a temporary tattoo paper and are interfaced to a conformal electronic interface that provides wireless data transmission. The skin-worn OP potentiometric sensor can withstand severe mechanical strains without compromising its analytical performance. The biosensor displays a wide dynamic range, fast response and high selectivity towards DFP (including efficient discrimination against organophosphate pesticides), and good reproducibility. The attractive performance of the new wearable biosensor indicates considerable promise for on-body threat detection towards rapid warning regarding potential exposure to G-series nerve agents. [ABSTRACT FROM AUTHOR]

A new non‐enzymatic glucose sensor based gold nanoparticle (AuNp)‐chitosan (Ch/AuNp) was developed in this study. Gold nanoparticles were synthesized by using the green synthesis method, in which chitosan is used as both reducing and stabilizing agent. Gold nanoparticle surfaces were modified with different molecular agents (4‐mercaptophenyl boronic acid,MPB, and 1‐decanethiol,DT) being sensitive to glucose. Modified gold nanoparticles were immobilized to electrode surfaces and used for the glucose measurements by the potentiometric method. The best working conditions were determined for the glucose measurements. It was found that linear working range is 0.5–30 mM, while limit of detection is 0.3 mM for the glucose measurement of the prepared non‐enzymatic sensor. It was stated that the prepared sensor could be used at least 6 times and glucose response decreased approximately 10.97 % when it is waited for 30 days. Interference effect of some molecules for glucose measurement was investigated and usability of developed sensor was tested in human blood serum. [ABSTRACT FROM AUTHOR]

A new biosensor for monitoring glucose levels in beverages is presented. The measurements are performed using potentiometric detection. Working electrodes are made using platinised paper as support and a biocompatible polymeric membrane made of a mixture of polyvinyl alcohol and chitosan containing glucose oxidase as the recognition layer. The system is based on the detection of the hydrogen peroxide generated by an enzymatic reaction performed in a highly sensitive, selective and simple way. The biosensors display suitable analytical performance (sensitivity −119.6 ± 6.4 mV/dec in the 0.03–1.0 mM range with a limit of detection of 0.02 mM). Determination of glucose in commercial orange juices is presented. These results were validated against conventional standard methods, showing good accuracy and fast analytical response. The methodology presented herein does not require complex samples treatment, offering an alternative to conventional methods, particularly for determinations performed with minimal expertise and without a laboratory infrastructure. [ABSTRACT FROM AUTHOR]

Six different sensors were fabricated and compared for the potentiometric determination of a widely used serotonin receptor agonist zolmitriptan (ZT), which is mainly used for the treatment of acute migraine attacks. Owing to its five-membered lactone ring, ZT was found susceptible to alkaline hydrolysis. The composition of PVC-membrane was systematically optimized via comparing the responses of different membranes. Membranes 1 to 4 contained dioctyl sebacate (DOS) in addition to different ion exchangers, namely, sodium tetraphenylborate (sensor 1), sodium phosphotungstate (sensor 2), sodium phosphomolybdate (sensor 3), and ammonium reineckate (sensor 4). The third sensor demonstrated the best sensitivity with near-Nernstian slope and was selected for the next step. To assess the plasticizer effect, the relatively non-polar plasticizer DOS used in sensor 3 was compared to high dielectric constant plasticizer nitrophenyl octyl ether (NPOE) in sensor 5; it was observed that the latter possessed better sensitivity (LOQ = 6.66 × 10−6 mol L−1), slope (52.821 mV decade−1), and response time. The effect of ionophore on sensor performance was evaluated, where hydroxypropyl β-cyclodextrin was further incorporated as an ionophore (sensor 6), resulting in remarkably higher sensitivity (LOQ = 3.33 × 10−6 mol L−1), better near-Nernstian slope (59.915 mV decade−1), and faster response time. The pH and temperature effects as well as the selectivities of the ionophore-free membrane (sensor 5) and the ionophore-containing membrane (sensor 6) were compared to evaluate the effect of the ionophore on the sensor performance. The developed sensors (5 and 6) were found to be selective for ZT in the presence of different interfering ions as well as a ZT alkaline degradation product. The sensor performances were assessed as per IUPAC recommendations and used for the determination of ZT in the presence of its degradation product in the raw material, orodispersable tablets, and in spiked plasma samples. The stability of sensor response over a wide pH range (pH 2 to 8) enabled selective inline ZT release profile monitoring at different physiological pH values in the presence of its hydrolytic degradation product. [ABSTRACT FROM AUTHOR]

This paper presents a dual functional extracellular recording biosensor based on a light-addressable potentiometric sensor (LAPS). The design and fabrication of this biosensor make it possible to record both extracellular membrane potential changes and ATP release from a single taste bud cell for the first time. For detecting ATP release, LAPS chip was functionalized with ATP-sensitive DNA aptamer by covalent immobilization. Taste bud cells isolated from rat were cultured on LAPS surface. When the desired single taste bud cell was illuminated by modulated light, ATP release from single taste bud cells can be measured by recording the shifts of bias voltage-photocurrent curves ( I-V curves) when the LAPS chip is working in discrete mode. On the other hand, extracellular membrane potential changes can be monitored by recording the fluctuation of LAPS photocurrent when the LAPS chip is working in continuous mode. The results show this biosensor can effectively record the enhancive effect of the bitter substance and inhibitory effect of the carbenoxolone (CBX) on the extracellular membrane potential changes and ATP release of single taste bud cells. In addition, the inhibitory effect of CBX also confirms LAPS extracellular recordings are originated from bitter signal transduction. It is proved this biosensor is suitable for extracellular recording of ATP release and membrane potential changes of single taste bud cells. It is suggested this biosensor could be applied to investigating taste signal transduction at the single-cell level as well as applied to other types of cells which have similar functions to taste bud cells. [ABSTRACT FROM AUTHOR]

The light-addressable potentiometric sensor (LAPS) is a spatially resolved biochemical sensor based on a field-effect structure. Over the past three decades, it has gained significant attention for the detection of various ions, biomolecules (e.g. enzymes, antibodies, DNA, and biomarkers), cellular metabolic activities as well as neuronal action potentials. To improve the sensor function and performance, all of these applications rely on the physical or chemical modifications of LAPS with different transducer materials and/or bio(chemical) recognition elements. With the rapid development of biomaterials associated with new sensing and fabrication techniques, remarkable advances in LAPS design, fabrication and applications have been achieved. In this review, the features and fabrication technologies of different gate insulators of LAPS are illustrated. Especially, ultrathin insulators such as organic monolayers are highlighted. The state-of-the-art technologies for LAPS modification and construction as well as their consequent applications in chemical and biological fields are summarized and discussed. Finally, current research challenges and future prospectives, for instance the combination of LAPS with microfluidic chips, will be presented. [ABSTRACT FROM AUTHOR]

The design of protein conformational switches-or proteins that change conformations in response to a signal such as ligand binding-has great potential for developing novel biosensors, diagnostic tools, and therapeutic agents. Among the defining properties of such switches, the response time has been the most challenging to optimize. Here we apply a computational design strategy in synergistic combination with biophysical experiments to rationally improve the response time of an engineered protein-based Ca2+-sensor in which the switching process occurs via mutually exclusive folding of two alternate frames. Notably, our strategy identifies mutations that increase switching rates by as much as 32-fold, achieving response times on the order of fast physiological Ca2+ fluctuations. Our computational design strategy is general and may aid in optimizing the kinetics of other protein conformational switches. [ABSTRACT FROM AUTHOR]

A potentiometric biosensor based on agarose-guar gum (A-G) entrapped bio-nanoconjugate of urease with gold nanoparticles (AUNps), has been reported for the first time for glyphosate detection. The biosensor is based on inhibition of urease activity by glyphosate, which was measured by direct potentiometry using ammonium ion selective electrode covered with A-G-urease nanoconjugate membrane. TEM and FTIR analysis revealed nanoconjugate formation and its immobilization in A-G matrix respectively. The composite biopolymer employed for immobilization yields thin, transparent, flexible membrane having superior mechanical strength and stability. It retains the maximum activity (92%) of urease with negligible leaching. The conjugation of urease with AUNps allows improvement in response characteristics for potentiometric measurement. The biosensor shows a linear response in the glyphosate concentration range from 0.5 ppm–50 ppm, with limit of detection at 0.5 ppm, which covers maximum residual limit set by WHO for drinking water. The inhibition of catalytic activity of urease nanoconjugate by gyphosate was confirmed by FTIR analysis. The response of fabricated biosensor is selective towards glyphosate as against various other pesticides. The biosensor exhibits good performance in terms of reproducibility and prolonged storage stability of 180 days. Thus, the present biosensor provides an alternative method for simple, selective and cost effective detection of glyphosate based on urease inhibition. [ABSTRACT FROM AUTHOR]

The nanoparticles (NPs) aggregates of commercial urease from jack beans ( Canavalia ensiformis ) were prepared by desolvation and glutaraldehyde crosslinking and functionalized by cysteamine dihydrochloride. These enzyme nanoparticles (ENPs) were characterized by transmission electron microscopy (TEM), UV and Fourier transform infrared (FTIR) spectroscopy. The TEM images of urease NPs showed their size in the range, 18–100 nm with an average of 51.2 nm. The ENPs were more active and stable with a longer shelf life than native enzyme molecules. The ENPs were immobilized onto chitosan (CHIT) activated nitrocellulose (NC) membrane via glutaraldehyde coupling with 32.22% retention of initial activity of free ureaseNPs with a conjugation yield of 1.63 mg/cm 2 . This NC membrane was mounted at the lower/sensitive end of the ammonium ion selective electrode (AISE) with O-ring and then electrode was connected to a digital pH meter to construct a potentiometric urea biosensor. The biosensor exhibited optimum response within 10 s at pH 5.5and 40 °C. The biosensor was employed for measurement of potentiometric determination of urea in sera of apparently healthy and persons suffering from kidney disorders. The biosensor displayed a low detection limit of 1 µM/L with a wide working range of 2–80 µM/L (0.002–0.08 mM) and sensitivity of 23 mV/decade. The analytical recovery of added urea in serum was 106.33%. The within and between-batch coefficient of variations (CVs) of present biosensor were 0.18% and 0.32% respectively. There was a good correlation (r = 0.99) between sera urea values obtained by reference method (Enzymic colorimetric kit method) and the present biosensor. The biosensor had negligible interference from Na + ,K + ,NH +4 and Ca 2+ but Mg 2+ ,Cu 2+ and ascorbic acid but had slight interference, which was overcome by specific ion selective electrode. The ENPs bound NC membrane was used maximally 8–9 times per day over a period of 180 days, when stored in 0.01 M sodium acetate buffer pH 5.5 at 4 °C. [ABSTRACT FROM AUTHOR]

The results of studying characteristics of potentiometric DP-sensors (sensors with the Donnan potential as their analytical signal) are presented for alkaline solutions of a sulfur-containing amino acid with perfluorosulfonic cation exchange membranes subjected to thermal treatment and mechanical deformation at different relative humidity. Correlation between the distribution of sensitivity of DP-sensors towards cations and anions and diffusion permeability of membranes was found. A multisensor system including two DP-sensors based on membranes with optimized properties and a glass electrode for codetermination of potassium cations and amino acid anions and zwitterions in solutions at pH > 7 are developed. [ABSTRACT FROM AUTHOR]

In the scientific context of membrane sensors and improved experimentation, we devised an experimentally designed protocol for sensor optimization. Two-step strategy was implemented for Umeclidinium bromide (UMEC) analysis which is a novel quinuclidine-based muscarinic antagonist used for maintenance treatment of symptoms accompanied with chronic obstructive pulmonary disease. In the first place, membrane components were screened for ideal ion exchanger, ionophore and plasticizer using three categorical factors at three levels in Taguchi design. Secondly, experimentally designed optimization was followed in order to tune the sensor up for finest responses. Twelve experiments were randomly carried out in a continuous factor design. Nernstian response, detection limit and selectivity were assigned as responses in these designs. The optimized membrane sensor contained tetrakis-[3,5-bis(trifluoro- methyl)phenyl] borate (0.44 wt%) and calix[6]arene (0.43 wt%) in 50.00% PVC plasticized with 49.13 wt% 2-ni­tro­phenyl octylether. This sensor, along with an optimum concentration of inner filling solution (2×10 −4 mol L −1 UMEC) and 2 h of soaking time, attained the design objectives. Nernstian response approached 59.7 mV/decade and detection limit decreased by about two order of magnitude (8×10 −8 mol L −1 ) through this optimization protocol. The proposed sensor was validated for UMEC determination in its linear range (3.16×10 −7 −1×10 −3 mol L −1 ) and challenged for selective discrimination of other congeners and inorganic cations. Results of INCRUSE ELLIPTA ® inhalation powder analyses obtained from the proposed sensor and manufacturer's UPLC were statistically compared. Moreover the proposed sensor was successfully used for the determination of UMEC in plasma samples. [ABSTRACT FROM AUTHOR]

A fully integrated system that combines extended gate field-effect transistor (EGFET)-based potentiometric biosensors and electrochemical impedance spectroscopy (EIS)-based biosensors has been demonstrated. This integrated configuration enables the sequential measurement of the same immunological binding event on the same sensing surface and consequently sheds light on the fundamental origins of sensing signals produced by FET and EIS biosensors, as well as the correlation between the two. Detection of both the bovine serum albumin (BSA)/anti-BSA model system in buffer solution and bovine parainfluenza antibodies in complex blood plasma samples was demonstrated using the integrated biosensors. Comparison of the EGFET and EIS sensor responses reveals similar dynamic ranges, while equivalent circuit modeling of the EIS response shows that the commonly reported total impedance change (DZtotal) is dominated by the change in charge transfer resistance (Rct) rather than surface capacitance (Csurface). Using electrochemical kinetics and the Butler-Volmer equation, we unveil that the surface potential and charge transfer resistance, measured by potentiometric and impedance biosensors, respectively, are, in fact, intrinsically linked. This observation suggests that there is no significant gain in using the FET/EIS integrated system and leads to the demonstration that low-cost EGFET biosensors are sufficient as a detection tool to resolve the charge information of biomolecules for practical sensing applications. [ABSTRACT FROM AUTHOR]

Using sensors to quantify clinically relevant biological species has emerged as a fascinating research field due to their potential to revolutionize clinical diagnosis and therapeutic monitoring. Taking advantage of the wide utility in clinical analysis and low cost of potentiometric ion sensors, we demonstrate a method to use such ion sensors to quantify bioanalytes without chemical labels. This is achieved by combination of chronopotentiometry with a mussel-inspired surface imprinting technique. The biomimetic sensing method is based on a blocking mechanism by which the recognition reaction between the surface imprinted polymer and a bioanalyte can block the current-induced ion transfer of an indicator ion, thus causing a potential change. The present method offers high sensitivity and excellent selectivity for detection of biological analytes. As models, trypsin and yeast cells can be measured at levels down to 0.03 U mL−1 and 50 CFU mL−1, respectively. [ABSTRACT FROM AUTHOR]

The present review work is devoted to potentiometric sensors based on high-temperature proton-conducting ceramic materials. The technology developments and possible application of such sensors for the determination of concentration of hydrogen-containing components in gases, solids and melts are described and thoroughly discussed. A special attention is devoted to the analysis of experimental data already appeared in international literature and their adequacy to the basic operation principles. On the base of this analysis, the existing problems and future trends are revealed and discussed. [ABSTRACT FROM AUTHOR]

The LAPS (light-addressable potentiometric sensor) platform is one of the most attractive approaches for chemical and biological sensing with many applications ranging from pH and ion/analyte concentration measurements up to cell metabolism detection and chemical imaging. However, although it is generally accepted that LAPS measurements are spatially resolved, the light-addressability feature of LAPS devices has not been discussed in detail so far. In this work, an extended electrical equivalent-circuit model of the LAPS has been presented, which takes into account possible cross-talk effects due to the capacitive coupling of the non-illuminated region. A shunting effect of the non-illuminated area on the measured photocurrent and addressability of LAPS devices has been studied. It has been shown, that the measured photocurrent will be determined not only by the local interfacial potential in the illuminated region but also by possible interfacial potential changes in the non-illuminated region, yielding cross-talk effects. These findings were supported by the experimental investigations of a penicillin-sensitive multi-spot LAPS and a metal-insulator-semiconductor LAPS as model systems. [ABSTRACT FROM AUTHOR]

Strategies to facilitate detection enhancement in various methods of nitrate detection are presented in this paper. The main nitrate detection methods for the past 10 years will be reviewed according to their advantages and disadvantages, followed by a focus on the techniques on increasing detection capabilities. For each detection method, an investigation of the technique of improvement is carried out. The utilisation of advance material such as membranes, reduction agents etc. is also identified as the key aspect for system improvement. Many researchers in the field of potentiometry, electrochemical, and biosensors have focused on miniaturising their detection systems to enhance the capability of nitrate in-situ measurement. The performance of miniaturised sensor systems is comparable to that of conventional systems. [ABSTRACT FROM AUTHOR]

A UO22+-PVC membrane electrode was constructed using 2-thenoyltrifluoroacetone as ionophore and its electrochemical response performance was characterized. The effect of membrane composition on the electrode performance was studied and best results were obtained using dioctylsebacate as a mediator and potassium tetrakis(4-chlorophenyl)borate as anion excluder. The optimized UO22+-sensor exhibited a Nernstian response with a slope of 29.5±0.5 mV decade−1 over the concentration range 5.0×10−7−1.0×10−1 mol L−1 at 25 °C with a detection limit of 3.1×10−7 mol L−1. The optimized electrode showed very good selectivity towards UO22+ relative to a wide variety of other cations and fast response time. Surface morphology of the optimized membrane electrode at different stages of its development and use was investigated and discussed. Quantum chemical calculations for geometrical optimization of the ionophore were carried out to investigate the interaction between the ionophore and UO22+ using DFT B3LYP/6-31++G(d,p) level of theory and the obtained data confirmed the proposed response mechanism. The developed sensor was successfully applied for UO22+ selective determination in real water samples and the obtained results were compared to those obtained by spectrophotometric method indicating no significant difference. [ABSTRACT FROM AUTHOR]

Light-addressable potentiometric sensors (LAPS) and scanning photo-induced impedance microscopy (SPIM) use photocurrent measurements at electrolyte-insulator-semiconductor substrates for spatiotemporal imaging of electrical potentials and impedance. The techniques have been used for the interrogation of sensor arrays and the imaging of biological systems. Sensor applications range from the detection of different types of ions and the label-free detection of charged molecules such as DNA and proteins to enzyme-based biosensors. Imaging applications include the temporal imaging of extracellular potentials and dynamic concentration changes in microfluidic channels and the lateral imaging of cell surface charges and cell metabolism. This paper will investigate the current state of the art of the measurement technology with a focus on spatial and temporal resolution and review the biological applications, these techniques have been used for. An outlook on future developments in the field will be given. [ABSTRACT FROM AUTHOR]

We developed a label-free potentiometric biosensor using tyrosinase extracted from Musa acuminata and immobilized by covalent bond on a surface of a solid-contact transducer. The transducer was manufactured containing two layers. The first layer contained a blend of poly(vinyl) chloride carboxylated (PVC-COOH), graphite and potassium permanganate. On this layer, we deposited a second layer containing just a mixture of poly(vinyl chloride) carboxylated and graphite. On the last layer of the transducer, we immobilized the tyrosinase enzyme by reaction with N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride. The solid-contact potentiometric biosensor presented at low detection limit of 7.3×10 −7 M and a linear range to catechol concentration between 9.3×10 −7 M and 8.3×10 −2 M. This biosensor was applied to determine the amount of total phenols in different samples of honey and propolis. The results agreed with the Folin-Ciocalteu method. [ABSTRACT FROM AUTHOR]

A potentiometric enzyme biosensor is a convenient detector for quantification of urea concentrations in industrial processes, or for monitoring patients with diabetes, kidney damage or liver malfunction. In this work, poly(3-hexylthiophene-co-3-thiopheneacetic acid) (P(3HT-co-3TAA)) was chemically synthesized, characterized and spin-coated onto conductive indium tin oxide (ITO) glass electrodes. Urease (Urs) was covalently attached to the smooth surface of this copolymer via carbodiimide coupling. The electrochemical behavior and stability of the modified Urs/P(3HT-co-3TAA)/ITO glass electrode were investigated by cyclic voltammetry, and the bound enzyme activity was confirmed by spectrophotometry. Potentiometric response studies indicated that this electrode could determine the concentration of urea in aqueous solutions, with a quasi-Nernstian response up to about 5 mM. No attempt was made to optimize the response speed; full equilibration occurred after 10 min, but the half-time for response was typically <1 min. [ABSTRACT FROM AUTHOR]

The five basic tastes namely sweetness, bitterness, sourness, saltiness and umami have been qualitatively and quantitatively analyzed using biomimetic sensors and biosensors listed in this review. This review puts great emphasis on the sensing materials or elements used in these sensors. Biomimetic sensors consist of potentiometric, voltammetric and impedance spectrum sensors modified with specific and designated biomimetic materials. More importantly, biosensors based on taste cells, tissues, nerves and enzyme as the sensing elements have been developed, and nanotechnology and microfluidic chip have been utilized for the fabrication of biosensors. There are two main aspects of practical application for five basic tastes via biomimetic sensors and biosensors: one aspect is to clarify taste sensation and transduction mechanism; another aspect is to obtain taste sensing information of food and pharmaceutical. The future perspectives for improvement of biomimetic sensors or biosensors are discussed. [ABSTRACT FROM AUTHOR]

Considering the ever-increasing population and trends in industrialization, it is difficult to detect the toxins produced in food products using traditional techniques. In this study, a potentiometric nanobiosensor technique using selective patterns forStaphylococcus aureusexotoxin was thoroughly considered. A molecular framework and polymer were produced using methacrylic acid (MAA) monomers, which formed covalent bonds between MAA monomers to produce a white polymer. In addition, hydrogen bonds formed between the amino acids of the exotoxin and the MAA functional groups, which functioned as selective sites for the polymer. To evaluate the effect of pH on theS. aureusexotoxin nanobiosensor, diluted solutions of NaOH and HNO3were applied for the upper and lower pH levels, respectively. The effect of temperature was tested using distilled water at fixed temperatures. The results showed that the molecular framework polymer (MFP) in the designed biosensor was able to detect an exotoxin density up to 10–3 M at 68 nm of synthesized molecularly imprinted polymer (MIP) during the first 32 days of the experiment (from a total of 56 days). The potential differences remained constants at an optimum pH range of 5.0–8.5 and at an optimum temperature range of 15°C–25°C. Therefore, we concluded that the pH and temperature can affect the precision of a potentiometric nanobiosensor for detectingS. aureusexotoxin. [ABSTRACT FROM AUTHOR]