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

Human olfactory receptor 17-40 as active part of a nanobiosensor: A microscopic investigation of its electrical properties

Increasing attention has been recently devoted to protein-based nanobiosensors. The main reason is the huge number of possible technological applications, going from drug detection to cancer early diagnosis. Their operating model is based on the protein activation and the corresponding conformational change, due to the capture of an external molecule, the so-called ligand. Recent measurements, performed with different techniques on human 17-40 olfactory receptor, evidenced a very narrow window of response in respect of the odour concentration. This is a crucial point for understanding whether the use of this olfactory receptor as sensitive part of a nanobiosensor is a good choice. In this paper we investigate the topological and electrical properties of the human olfactory receptor 17-40 with the objective of providing a microscopic interpretation of available experiments. To this purpose, we model the protein by means of a graph able to capture the mean features of the 3D backbone structure. The graph is then associated with an equivalent impedance network, able to evaluate the impedance spectra of the olfactory receptor, in its native and activated state. We assume a topological origin of the different protein electrical responses to different ligand concentrations: In this perspective all the experimental data are collected and interpreted satisfactorily within a unified scheme, also useful for application to other proteins.Comment: 6 pages, 6 figures, DOI:10.1039/c1ra0002

Novel molecularly imprinted impedimetric biosensor based on polypyrrole and decorated graphene oxide for the routine monitoring of Lysozyme

In this work, a novel molecularly imprinted polymer based on polypyrrole (PPy) and decorated graphene oxide (GO@Fe3O4) was developed for the sensitive detection of lysozyme (LYS). The synthesized material (MIPPy/GO@Fe3O4) was electrodeposited with LYS as a template on gold microelectrodes. Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) were used to confirm the adequate preparation of GO@Fe3O4, and the characterization of the resulting microsensors was carried out with the following analytical techniques: electrochemical impedance spectrometry (EIS), FT-IR analysis and scanning electron microscopy (SEM). An equivalent circuit was suggested to quantitatively analyse each component of the sensor system. EIS was also used for the determination of LYS in a wide linear range from 1 to 1 105 pg/mL, presenting good precision (RSD ≈ 10%, n = 5) and low limits of detection and quantification (LOD = 0.009 pg/mL and LOQ = 0.9 pg/mL, respectively). Meanwhile, the microsensor showed a high sensitivity, a good selectivity and reproducibility. The construction process was relatively simple, and provided a rapid and economical method for the routine monitoring of LYS. The microsensor was successfully applied for the detection of this protein in fresh chicken-egg white sample and commercial drug.Campus de Excelencia Internacional Andalucía Tech. Beca FPU18/05371 Proyecto de la Junta de Andalucía UMA18FEDERJA06

Los mundos [teóricos] de Coraline: Psicoanálisis, Postfeminismo y Postmodernismo en el cine de animación

[ES] Este artículo contribuye al estudio de diferentes metodologías como modo de aproximación al estudio teórico sobre la animación, utilizando como caso de estudio la película de animación Los Mundos de Coraline (Henry Selick, 2009), que incorpora a su complejo hilo argumental ideas procedentes de diversos movimientos histórico-sociales y filosóficos. Además, esta investigación justifica la necesidad de integrar en el actual cine de animación una fuerte inspiración teórica en la narrativa, además de las innovaciones tecnológicas que se desarrollan paralelamente. A través de la revisión de esta producción animada, se alega que los personajes animados pueden y deben ser protagonistas de narrativas tan profundas como las que aquí se tratan, ya que la animación tiene la potencialidad de incidir profundamente en cuestiones como la confirmación de la identidad o el desarrollo cognitivo del personaje protagonista, a través de la simbólica visualización de sus experiencias, miedos y frustraciones en el camino hacia su madurez.Martínez González, E. (2011). Los mundos [teóricos] de Coraline: Psicoanálisis, Postfeminismo y Postmodernismo en el cine de animación. Con A de Animación. (1):79-96. doi:10.4995/caa.2011.8627996

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