Potentiality of application of the conductometric L-arginine biosensors for the real sample analysis

Aim. To determine an influence of serum components on the L-arginine biosensor sensitivity and to formulate practical recommendations for its reliable analysis. Methods. The L-arginine biosensor comprised arginase and urease co-immobilized by cross-linking. Results. The biosensor specificity was investigated based on a series of representative studies (namely, through urea determination in the serum; inhibitory effect studies of mercury ions; high temperature treatment of sensors; studying the biosensor sensitivity to the serum treated by enzymes, and selectivity studies). It was found that the response of the biosensor to the serum injections was determined by high sensitivity of the L-arginine biosensor toward not only to L-arginine but also toward two other basic amino acids (L-lysine and L-histidine). Conclusions. A detailed procedure of optimization of the conductometric biosensor for L-arginine determination in blood serum has been proposed. Keywords: L-arginine, conductometric biosensors, serum, optimization procedure.Мета. Визначити вплив компонентів сироватки крові на чутливість біосенсора при виявленні L-аргініну та сформулювати практичні рекомендації для забезпечення її надійного аналізу. Методи. Біосенсор для визначення L-аргініну містить аргіназу і уреазу, коіммобілізовані методом поперечного зшивання. Результати. Специфічність біосенсора вивчали на основі низки показників – вмісту сечовини у сироватці; інгібувального впливу іонів ртуті; високотемпературної обробки біосенсорів; чутливості біосенсора до сироватки крові, обробленої ліофілізованими препаратами ферментів, та селективності біосенсора. Встановлено, що відгук біосенсора на внесення сироватки зумовлений високою чутливістю біосенсора ще до двох, крім L-аргініну, основних амінокислот (L-лізину та L-гістидину). Висновки. Запропоновано детальну процедуру оптимізації кондуктометричного біосенсора для визначення L-аргініну у сироватці крові. Ключові слова: L-аргінін, кондуктометричні біосенсори, сироватка крові, процедура оптимізації.Цель. Определить влияние компонентов сыворотки крови на чувствительность биосенсора для выявления L-аргинина и сформулировать практические рекомендации для обеспечения ее надежного анализа. Методы. Биосенсор для определения L-аргинина содержит аргиназу и уреазу, ко-иммобилизованные методом поперечной сшивки. Результаты. Специфичность биосенсора изучали на основе серии показателей – содержания мочевины в сыворотке; ингибирующего эффекта ионов ртути; высокотемпературной обработки биосенсоров; чувствительности биосенсора к сыворотке крови, обработанной лиофилизованными препаратами ферментов, и селективности биосенсора. Установлено, что отклик биосенсора на внесение сыворотки обусловлен высокой чувствительностью биосенсора еще к двум, кроме L-аргинина, основным аминокислотам (L-лизину и L-гистидину). Выводы. Предложена детальная процедура оптимизации кондуктометрического биосенсора для определения L-аргинина в сыворотке крови. Ключевые слова: L-аргинин, кондуктометрические биосенсоры, сыворотка крови, процедура оптимизации

Measurement of Electromagnetic Activity of Yeast Cells at 42 GHz

This paper discusses the possibility of using a device composed of a resonant cavity, preamplifiers, and a spectrum analyzer to detect electromagnetic emission of yeast cells at a frequency of about 42 GHz. Measurement in this frequency range is based on the Frohlich\'s postulate of coherent polar oscillations as a fundamental biophysical property of biological systems and on the experiments of Grundler and Keilmann who disclosed effects of exposure to the electromagnetic field at 42 GHz on the growth rate of yeast cells. This article includes a detailed description of the laboratory equipment and the methods used to evaluate the obtained results

A Fully Integrated Electrochemical BioMEMS Fabrication Process for Cytokine Detection: Application for Heart Failure

AbstractIn this present study, a fully integrated BioMEMS was developed using silicon technology to simultaneously detect varying cytokine biomarkers: interleukin-1 (IL-1), interleukin-10 (IL-10), and interleukin-6 (IL-6) using eight gold working microelectrodes (WE). The biomarkers are one of many antigens that are secreted in acute stages of inflammation after left ventricle assisted device (LVAD) implantation for patients suffering from heart failure (HF). The monoclonal antibodies (mAb): anti-human IL-1, IL-10, and IL-6 were immobilized onto gold microelectrodes through functionalization with carboxyl diazonium, respectively. Cyclic voltammetry (CV) was applied during the microelectrode functionalization process to characterize the gold microelectrode surface properties, while electrochemical impedance spectroscopy (EIS) was used to characterize the modified gold microelectrodes. The BioMEMS was highly sensitive towards the three cytokines in a range of 1 pg/mL to 15 pg/mL, which is the window where acute inflammations were observed

Characterization of different DLC and DLN electrodes for biosensor design

International audienceDiamond-Like Carbon and Carbon-Like Nanocomposite electrodes, novel materials in the field of biosensors, made with different ratio of sp3/sp2 carbon hybridization or doped with elements such as Ni, Si and W, were characterized electrochemically by cyclic voltammetry and by amperometric measurements towards hydrogen peroxide. SiCAr1 and SiCNi5% were chosen as sensitive transducers for elaboration of amperometric glucose biosensors. Immobilization of glucose oxidase was carried out by cross-linking with glutareldehyde. Measurements were made at a fixed potential + 1.0 V in 40 mM phosphate buffer pH 7.4. SiCAr1 seems to be more sensitive for glucose (0.6875 µA/mM) then SiCNi5% (0.3654 µA/mM). Detections limits were respectively 20 µM and 30 µM. Michaelis-Menten constants for the two electrodes were found around 3 mM. 48% and 79% of the original response for 0.5 mM glucose remained respectively for both electrodes after 10 days

Structure, electrochemical properties and functionalization of amorphous CN films deposited by femtosecond pulsed laser ablation

Amorphous carbon nitride (a-C:N) material has attracted much attention in research and development. Recently, it has become a more promising electrode material than conventional carbon based electrodes in electrochemical and biosensor applications. Nitrogen containing amorphous carbon (a-C:N) thin films have been synthesized by femtosecond pulsed laser deposition (fs-PLD) coupled with plasma assistance through Direct Current (DC) bias power supply. During the deposition process, various nitrogen pressures (0 to 10 Pa) and DC bias (0 to ¿ 350 V) were used in order to explore a wide range of nitrogen content into the films. The structure and chemical composition of the films have been studied by using Raman spectroscopy, electron energy-loss spectroscopy (EELS) and high-resolution transmission electron microscopy (HRTEM). Increasing the nitrogen pressure or adding a DC bias induced an increase of the N content, up to 21 at.%. Nitrogen content increase induces a higher sp2 character of the film. However DC bias has been found to increase the film structural disorder, which was detrimental to the electrochemical properties. Indeed the electrochemical measurements, investigated by cyclic voltammetry (CV), demonstrated that a-C:N film with moderate nitrogen content (10 at.%) exhibited the best behavior, in terms of reversibility and electron transfer kinetics. Electrochemical grafting from diazonium salts was successfully achieved on this film, with a surface coverage of covalently bonded molecules close to the dense packed monolayer of ferrocene molecules. Such a film may be a promising electrode material in electrochemical detection of electroactive pollutants on bare film, and of biopathogen molecules after surface grafting of the specific affinity receptor.This work is produced with the financial support of the Future Program Lyon Saint-Etienne (PALSE) from the University of Lyon (ANR-11-IDEX-0007), under the “Investissements d'Avenir” program managed by the National Agency Research (ANR)

Microcapteurs électrochimiques pour des mesures durables en Environnement-Santé et Agroalimentaire

National audienc