The work was aimed at the development of a biosensor array for the simultaneous determination of six solutes (glutamate, glucose, choline, acetylcholine, lactate, and pyruvate) in aqueous solutions. ...Enzymes selective for these substrates were immobilized on the surface of amperometric platinum disc electrodes and served as bioselective elements of a biosensor array. Direct enzymatic analysis by the developed biosensors provided high sensitivity to the tested substrates (limits of detection were 1–5 μM). The linear ranges of the biosensors were from 0.001–0.01 mM to 0.2–2.5 mM. The influence of solution pH, ionic strength and buffer capacity on the biosensor responses was investigated; the conditions for simultaneous operation of all the bioselective elements were optimized. The absence of any cross-influence of the substrates of enzymatic systems used was shown as well as a high selectivity of the biosensors and the absence of any impact of interfering substances (ascorbic acid, dopamine, cysteine, paracetamol). The developed biosensor array had good response reproducibility and storage stability. The array is suitable for rapid (0.5–1 min) and simple simultaneous determination of glutamate, glucose, choline, acetylcholine, lactate, and pyruvate in aqueous (biological) samples; furthermore, the creation of a single chip with six sensitive elements is possible as well as the addition of other biosensors.
•A biosensor array for neurotransmitter and metabolite determination was created.•It is based on enzymes immobilized on platinum disc electrodes.•Quick response, simplicity, and low cost are advantages of the biosensor array.•The biosensor array can be used for the analysis of aqueous sample composition.
Electrochemical enzyme-based biosensors are one of the largest and commercially successful groups of biosensors. Integration of nanomaterials in the biosensors results in significant improvement of ...biosensor sensitivity, limit of detection, stability, response rate and other analytical characteristics. Thus, new functional nanomaterials are key components of numerous biosensors. However, due to the great variety of available nanomaterials, they should be carefully selected according to the desired effects. The present review covers the recent applications of various types of nanomaterials in electrochemical enzyme-based biosensors for the detection of small biomolecules, environmental pollutants, food contaminants, and clinical biomarkers. Benefits and limitations of using nanomaterials for analytical purposes are discussed. Furthermore, we highlight specific properties of different nanomaterials, which are relevant to electrochemical biosensors. The review is structured according to the types of nanomaterials. We describe the application of inorganic nanomaterials, such as gold nanoparticles (AuNPs), platinum nanoparticles (PtNPs), silver nanoparticles (AgNPs), and palladium nanoparticles (PdNPs), zeolites, inorganic quantum dots, and organic nanomaterials, such as single-walled carbon nanotubes (SWCNTs), multi-walled carbon nanotubes (MWCNTs), carbon and graphene quantum dots, graphene, fullerenes, and calixarenes. Usage of composite nanomaterials is also presented.
Application of nanomaterials greatly improves performance of electrochemical enzyme-based biosensors.
The paper presents a simple and inexpensive reusable biosensor for determination of the concentration of adenosine-5′-triphosphate (ATP) in aqueous samples. The biosensor is based on a conductometric ...transducer which contains two pairs of gold interdigitated electrodes. An enzyme hexokinase was immobilized onto one pair of electrodes, and bovine serum albumin-onto another pair (thus, a differential mode of measurement was used). Conditions of hexokinase immobilization on the transducer by cross-linking via glutaraldehyde were optimized. Influence of experimental conditions (concentration of magnesium ions, ionic strength and concentration of the working buffer) on the biosensor work was studied. The reproducibility of biosensor responses and operational stability of the biosensor were checked during one week. Dry storage at −18°C was shown to be the best conditions to store the biosensor. The biosensor was successfully applied for measurements of ATP concentration in pharmaceutical samples. The proposed biosensor may be used in future for determination of ATP and/or glucose in water samples.
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•A conductometric biosensor for determination of adenosine triphosphate was created.•It is based on enzyme hexokinase immobilized on interdigitated planar electrodes.•Quick response, simplicity, and low cost are advantages of the biosensor.•The biosensor can be used in for determination of ATP in water samples.
In the review, the principles and main purposes of using multienzyme systems in electrochemical biosensors are analyzed. Coupling several enzymes allows an extension of the spectrum of detectable ...substances, an increase in the biosensor sensitivity (in some cases, by several orders of magnitude), and an improvement of the biosensor selectivity, as showed on the examples of amperometric, potentiometric, and conductometric biosensors. The biosensors based on cascade, cyclic and competitive enzyme systems are described alongside principles of function, advantages, disadvantages and practical use for real sample analyses in various application areas (food production and quality control, clinical diagnostics, environmental monitoring). The complications and restrictions regarding the development of multienzyme biosensors are evaluated. The recommendations on the reasonability of elaboration of novel multienzyme biosensors are given.
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•Biosensors based on cascade, cyclic and competitive enzyme systems are described.•Advantages and limitations of multienzyme electrochemical biosensors are analyzed.•Multienzyme systems allow an extension of the spectrum of detectable substances.•An improvement of the biosensor sensitivity and selectivity is possible.
In this work, we developed a new amperometric biosensor for glutamate detection using a typical method of glutamate oxidase (GlOx) immobilization via adsorption on silicalite particles. The disc ...platinum electrode (
d
= 0.4 mm) was used as the amperometric sensor. The procedure of biosensor preparation was optimized. The main parameters of modifying amperometric transducers with a silicalite layer were determined along with the procedure of GlOx adsorption on this layer. The biosensors based on GlOx adsorbed on silicalite demonstrated high sensitivity to glutamate. The linear range of detection was from 2.5 to 450 μM, and the limit of glutamate detection was 1 μM. It was shown that the proposed biosensors were characterized by good response reproducibility during hours of continuous work and operational stability for several days. The developed biosensors could be applied for determination of glutamate in real samples.
This review analyzes electrochemical biosensors for the determination of lactate (lactic acid) and pyruvate (pyruvic acid) concentrations in liquid samples, especially in the blood serum. The ...biosensor systems for the simultaneous determination of both substances and commercial variants of the biosensors are presented, and the biosensors for medical diagnostics are highlighted. The information concerning the necessity of separate and simultaneous determination of lactate and pyruvate, as well as lactate to pyruvate ratio, is given; the traditional methods for the determination of these substances are briefly described. Lactate dehydrogenase and lactate oxidase are shown to be most commonly used in the biosensors for lactate detection. Pyruvate oxidase and living cells are used in the biosensors for pyruvate detection. Different methods of the enzymes immobilization are presented, as well as strategies for enhancement of the biosensor sensitivity. An additional requirement for practical applications is the biosensor resistance to electroactive interferents, inhibitors, biofouling, and electrode passivation; thus, the variants of solving these problems in the biosensors for lactate and pyruvate detection are analyzed.
•Necessity of the detection of lactate, pyruvate and their ratio in blood is shown.•Electrochemical biosensors for the lactate and pyruvate determination are compared.•The biosensors contain lactate dehydrogenase, lactate oxidase, or pyruvate oxidase.•Biosensor systems (arrays) and commercial variants of the biosensors are presented.•The importance of further development of such biosensors is discussed.
The aim of this work was to develop an array of biosensors for simultaneous determination of four carbohydrates in solution. Several enzyme systems selective to lactose, maltose, sucrose and glucose ...were immobilised on the surface of four conductometric transducers and served as bio-recognition elements of the biosensor array. Direct enzyme analysis carried out by the developed biosensors was highly sensitive to the corresponding substrates. The analysis lasted 2min. The dynamic range of substrate determination extended from 0.001mM to 1.0–3.0mM, and strongly depended on the enzyme system used. An effect of the solution pH, ionic strength and buffer capacity on the biosensors responses was investigated; the conditions of simultaneous operation of all biosensors were optimised. The data on cross-impact of the substrates of all biosensors were obtained; the biosensor selectivity towards possible interfering carbohydrates was tested. The developed biosensor array showed good signal reproducibility and storage stability. The biosensor array is suited for simultaneous, quick, simple, and selective determination of maltose, lactose, sucrose and glucose.
•We developed an array of 4 conductometric biosensors based on hydrolytic enzymes.•Conditions for simultaneous operation of all biosensors were selected.•Biosensor array showed good signal reproducibility and storage stability.•The possibility of simultaneous selective determination of carbohydrates was shown.
Creatine kinase (CK: adenosine-5-triphosphate–creatine phosphotransferase) is an important enzyme of muscle cells; the presence of a large amount of the enzyme in blood serum is a biomarker of ...muscular injuries, such as acute myocardial infarction. This work describes a bi-enzyme (glucose oxidase and hexokinase based) biosensor for rapid and convenient determination of CK activity by measuring the rate of ATP production by this enzyme. Simultaneously the biosensor determines glucose concentration in the sample. Platinum disk electrodes were used as amperometric transducers. Glucose oxidase and hexokinase were co-immobilized via cross-linking with BSA by glutaraldehyde and served as a biorecognition element of the biosensor. The biosensor work at different concentrations of CK substrates (ADP and creatine phosphate) was investigated; optimal concentration of ADP was 1mM, and creatine phosphate – 10mM. The reproducibility of the biosensor responses to glucose, ATP and CK during a day was tested (relative standard deviation of 15 responses to glucose was 2%, to ATP – 6%, to CK – 7–18% depending on concentration of the CK). Total time of CK analysis was 10min. The measurements of creatine kinase in blood serum samples were carried out (at 20-fold sample dilution). Twentyfold dilution of serum samples was chosen as optimal for CK determination. The biosensor could distinguish healthy and ill people and evaluate the level of CK increase. Thus, the biosensor can be used as a test-system for CK analysis in blood serum or serve as a component of multibiosensors for determination of important blood substances. Determination of activity of other kinases by the developed biosensor is also possible for research purposes.
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•Reusable amperometric enzyme biosensor for creatine kinase detection was developed.•Optimal concentrations of creatine phosphate and ADP were studied.•Conditions for measurements of real samples were determined.•Different concentrations of creatine kinase in blood serum were measured.
Potentiometric biosensor based on two identical pH-sensitive field-effect transistors for urea determination was developed. Recombinant urease with low affinity to urea (Km=200mM) was immobilized via ...entrapment in PVA/SbQ photopolymer on one transistor and served as a biorecognition element of the biosensor, while bovine serum albumin in PVA/SbQ photopolymer placed on the second transistor was used for reference. Biosensor was characterized by a wide range of urea determination: 0.5–15mM linear range (operational detection range – 0.5–40mM) and quick response time (1–2min). Samples of blood serum and hemodialysate without urea caused no biosensor response. All this allowed analysis of blood serum samples that were diluted 10 times, what led to smaller measurement error in comparison with 100–500 times dilution in case of biosensors based on non-modified urease from soy beans. Urea concentrations in 10 samples of serum were determined; biosensor results correlated well with two control methods of urea measurement. Furthermore, kinetics of decreasing urea concentration in dialysate during hemodialysis was demonstrated. Biosensor measurements of dialysate samples were verified by traditional colorimetric determination of urea. Proposed biosensor can be effectively used for analysis of samples with different concentrations of urea and for hemodialysis control. What is more, characteristics of the biosensor make possible real-time measurements of urea concentration during hemodialysis by pumping dialysis fluid through the working cell. Biosensor showed no significant decrease of responses during 5 month of storage.
Dopamine is a biologically active chemical that performs a number of vital functions as a hormone and neurotransmitter. Therefore, the determination of dopamine concentration in the human body is ...important for biomedical research. The content of dopamine in the blood varies depending on the age of a healthy person and can serve as a prognostic marker of many diseases. The aim of this work was to develop a new enzyme conductometric biosensor for the determination of dopamine in aqueous samples and to study the biosensor's analytical characteristics. The conductometric method of analysis with differential measurement mode was used in the work. Two pairs of gold interdigitated electrodes deposited on a sitall substrate were used as a conductometric transducer. The biorecognition element of the biosensor was based on laccase immobilized by glutaraldehyde cross‐linking. The optimal conditions of laccase immobilization were selected. The influence of solution parameters (ionic strength, pH, buffer capacity) on the biosensor work was investigated. The biosensors demonstrated high sensitivity to dopamine (minimum limit of detection −7.8 μM) with the linear range up to 1 mM. The biosensor was highly selective and reusable. The proposed biosensor was tested regarding the possibility of its long‐term storage under different conditions. The developed conductometric biosensor was proven to be suitable for measuring dopamine concentration in biological and pharmaceutical samples.
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