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 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.
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 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.
The aim of the work were the optimization of an amperometric glutamate-sensitive biosensor and its utilization for the determination of the glutamate concentrations in food samples. Amperometric ...method of measurements was used. The biosensor was based on immobilized glutamate oxidase and platinum disc electrode. The biosensor was connected to the working cell with auxiliary (platinum wire) and reference (Ag/AgCl) electrodes. The biosensor exhibited high sensitivity to glutamate, duration of one analysis was about 5 min. An influence of the ionic strength, pH, and buffer capacity on the biosensor operation was investigated. The sensitivity of biosensor to various possible interfering substances, including amino acids, was studied; high selectivity to glutamate was shown. The reproducibility of analysis of food samples and an impact of sample dilution was evaluated. Glutamate concentrations in different sauces and seasonings were measured by the developed biosensor; the results correlated well with those obtained by the spectrophotometric method (R2 = 0,988). Thus, the amperometric biosensor for glutamate determination was successfully optimized and used for measurement of glutamate concentrations in sauces and seasonings.
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.
Today, one of the main causes of disability and mortality in the world's population is the disease of the cardiovascular and central nervous systems. Therefore, the development of new highly ...effective drugs for their treatment becomes an urgent task of modern medicine and pharmacy. Promising in this direction is the creation of a new medicinal product, which combines the active donor NO – neurotransmitter amino acid L-arginine, as well as the famous domestic antioxidant – thiotriazoline. A rational dosage form – pills was chosen to create a new combined drug. Therefore, the actual and timely task is to develop methods for standardizing the active substances in the model mixture, which in future can become the basis for the analysis of the finished dosage forms of the new drug. The purpose of the work is to develop a method for standardizing the model mixture of L-arginine and thiotriazoline in the ratio of 4:1 by HPLC method. Materials and methods. During the research, certified substances L-arginine (manufacturer: Sigma-Aldrich, USA) and thiotriazolin (manufacturer State Enterprise “Chemical Reagents Plant” of the Scientific-Technological Complex “Institute of Single Crystals” of the National Academy of Sciences of Ukraine) were used. The research was carried out using LC-20 Prominence Shimadzu Chromatograph. Results. First, in the laboratory, six series of model mixture of L-arginine and thiotriazoline were produced in an optimum ratio of 4:1. Continuously, the test solution and the solution of the working standard sample, were chromatographed obtaining at least three chromatograms for each solution. It is established that the content of L-arginine in the model mixture ranges from 198.38 mg to 200.66 mg, and thiotriazoline is from 50.82 mg to 51.61 mg. According to the content of the active substances, the studied series of model mixture of L-arginine and thiotriazoline in a ratio of 4:1 correspond to the requirements of the SPF. Conclusions. In the course of the conducted researches the method of standardization of active substances of the model mixture of L-arginine and thiotriazoline in a ratio of 4:1 by the HPLC method, which is reproducible, accurate and can be used later in the quality control of the established tablet formulation, has been developed.
Introduction. An actual task of modern medicine is the development of treatment methods of the central nervous system diseases. The solution of this problem was the creation of new, more effective ...neuropsychotropic drug that shows pronounced antidepressant, nootropic, neuroprotective and antioxidant effects based on the fixed combination of L-tryptophan with thiotriazoline. One of the steps in creating a new drug is the standardization of active ingredients. Today, much attention is being paid to new physical-chemical methods of drugs study, including high-performance liquid chromatography (HPLC). Increasingly, the HPLC method is used for the determination of active ingredients of organic nature, both in mono-preparations and in combined dosage forms. Therefore, we have proposed the HPLC method for new combined L-tryptophan and thiotriazoline drug in order to determine active substances based on their effects. The purpose of our study is to develop a method for the simultaneous standardization of L-tryptophan and thiotriazoline in an artificial compound by high-performance liquid chromatography, in particular the selection of the mobile and stationary phase. Materials and methods. In the first stage of our work, a selection of phase and eluents was carried out for L-tryptophan and thiotriazoline model compound in a ratio of 1:1. The analysis method of thiotriazoline in the reverse phase (C 18) using the eluents, which are water-methanol compounds, was taken as a basis. Results. In the course of study, it was found that the retention volume of both tryptophan and thiotriazoline decreased, and the peak distribution coefficient increased with the number of theoretical plates with increasing content of methanol in phosphate buffer compound. Therefore, as an eluent, attention was drawn to a solution of 20% methanol with 80 % phosphate buffer. Under these conditions, the tryptophan retention volume was 15.11 ml, thiotriazoline – about 6.05 ml, the efficacy of the chromatographic column, calculated on the tryptophan peak of about 3300 theoretical plates. Findings: A highly sensitive technic was developed as part of the study for the simultaneous determination of L-tryptophan and thiotriazoline in a model mixture by HPLC (high performance liquid chromatography method, that is planned to be used in further study, was developed as a part of the study. The method is developed not only for L-tryptophan and thiotriazoline standardization in the combined drug, but also for their determination in biological fluids.
Aim. Development of an amperometric biosensor for measuring choline concentration in water samples. Methods. A bioselective element of the biosensor was created using choline oxidase which was ...covalently immobilized by glutaraldehyde crosslinking with bovine serum albumin on the surface of an amperometric platinum disk electrode. Results. The conditions of the bioselective element formation (the enzyme and glutaraldehyde concentrations, time of procedure) were optimized. The biosensor developed was characterized by good response reproducibility over hours of continuous operation. The linear range of substrate determination ranged from 10 µM to 1000 µM, a limit of choline detection – 1–3 µM, the biosensor sensitivity was 25–30 nA/mM. An effect of interfering substances was significantly reduced by the application of an additional semipermeable poly-m-phenylenediamine (PPD) membrane. Conclusions. The developed biosensor is well-suited for choline determination in water samples.