Study of zeolite influence on analytical characteristics of urea biosensor based on ion-selective field-effect transistors

A possibility of the creation of potentiometric biosensor by adsorption of enzyme urease on zeolite was investigated. Several variants of zeolites (nano beta, calcinated nano beta, silicalite, and nano L) were chosen for experiments. The surface of pH-sensitive field-effect transistors was modified with particles of zeolites, and then the enzyme was adsorbed. As a control, we used the method of enzyme immobilization in glutaraldehyde vapour (without zeolites). It was shown that all used zeolites can serve as adsorbents (with different effectiveness). The biosensors obtained by urease adsorption on zeolites were characterized by good analytical parameters (signal reproducibility, linear range, detection limit and the minimal drift factor of a baseline). In this work, it was shown that modification of the surface of pH-sensitive field-effect transistors with zeolites can improve some characteristics of biosensors

Elaboration of Urease Adsorption on Silicalite for Biosensor Creation

A possibility of efficient urease adsorption on silicalite for the purpose of biosensor creation was investigated. The procedure of urease adsorption on silicalite is notable for such advantages as simple and fast performance and non-use of toxic or auxiliary compounds. Optimal conditions for modifying transducer surfaces with silicalite and subsequent urease adsorption on these surfaces were selected. The working parameters of the created biosensor were optimized. The developed biosensor with adsorbed urease was characterized by good intra-reproducibility (RSD 4.5?%), improved inter-reproducibility (RSD of urea determination is 9?%) and operational stability (less than 10?% loss of activity after 10 days). Besides, the developed method for enzyme adsorption on silicalite was compared with the traditional methods of urease immobilization in biosensorics. Working conditions of the produced biosensor (pH and ionic strength) were shown to be close to those of the biosensor based on urease immobilized in GA vapor. For these reasons, it was concluded that the method of enzyme adsorption on silicalite is well-suited for biosensor standardization aimed at its further manufacture

Influence of Composition of Zeolite/Enzyme Nanobiocomposites on Analytical Characteristics of Urea Biosensor Based on Ion-Selective Field-Effect Transistors

Zeolite/enzyme nanobiocomposites of different compositions were tested in this work for the improvement of biosensor analytical characteristics. The bioselective element based on urease immobilized by cross-linking with glutaraldehyde was used as a model. The working characteristics of biosensors based on various zeolite/enzyme nanocomposites were examined and compared with those of urease-based biosensors. An optimal concentration of zeolytes beta (BEA) in bioselective elements is determined to be 1.5%. It ensures as wide linear range of measurement without remarkable loss in biosensor sensitivity to urea. The BEA zeolite-based biosensors were shown to have better working parameters in comparison with those based on zeolites A (LTA). A decrease in biosensor sensitivity to heavy metal ions was demonstrated for all zeolites used, which testifies to probable increase in stability of urea measurement in real environmental samples

Development of novel enzyme potentiometric biosensor based on pH-sensitive field-effect transistors for aflatoxin B1 analysis in real samples

International audienceThis study aimed at the development and optimization of a potentiometric biosensor based on pH-sensitive field-effect transistors and acetylcholinesterase for aflatoxin B1 determination in real samples. Optimal conditions for bioselective elements operation were defined and analytical characteristics of the proposed biosensor were studied. The proposed biosensor characterized high operational stability and reproducibility of signal. Selectivity of acetylcholinesterase-biosensor to aflatoxins in relation to other groups of toxic substances was analyzed. The developed biosensor was applied to the determination of aflatoxin B1 in real samples (sesame, walnut and pea)

Determination of total creatine kinase activity in blood serum using an amperometric biosensor based on glucose oxidase and hexokinase

International audienceCreatine 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 1 mM, and creatine phosphate - 10 mM. 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 CM - 7-18% depending on concentration of the CK). Total time of CM analysis was 10 min. 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 CM determination. The biosensor could distinguish healthy and ill people and evaluate the level of CM increase. Thus, the biosensor can be used as a test-system for CM 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 purpose

Development of Silicalite/Glucose Oxidase-Based Biosensor and Its Application for Glucose Determination in Juices and Nectars

The application of silicalite for improvement of enzyme adsorption on new stainless steel electrodes is reported. Glucose oxidase (GOx) was immobilized by two methods: cross-linking by glutaraldehyde (GOx-GA) and cross-linking by glutaraldehyde along with GOx adsorption on silicalite-modified electrode (SME) (GOx-SME-GA). The GOx-SME-GA biosensors were characterized by a four- to fivefold higher sensitivity than GOx-GA biosensor. It was concluded that silicalite together with GA sufficiently enhances enzyme adhesion on stainless steel electrodes. The developed GOx-SME-GA biosensors were characterized by good reproducibility of biosensor preparation (relative standard deviation (RSD)—18 %), improved signal reproducibility (RSD of glucose determination was 7 %), and good storage stability (29 % loss of activity after 18-day storage). A series of fruit juices and nectars was analyzed using GOx-SME-GA biosensor for determination of glucose concentration. The obtained results showed good correlation with the data of high-performance liquid chromatography (HPLC) (R = 0.99)