Electrochemical detection of peroxynitrite using hemin-PEDOT functionalized boron-doped diamond microelectrode.

Peroxynitrite is a potent nitroxidation agent and highly reactive metabolite, clinically correlated with a rich pathophysiology. Its sensitive and selective detection is challenging due to its high reactivity and short sub-second lifetime. Boron-doped diamond (BDD) microelectrodes have attracted interest because of their outstanding electroanalytical properties that include a wide working potential window and enhanced signal-to-noise ratio. Herein, we report on the modification of a BDD microelectrode with an electro-polymerized film of hemin and polyethylenedioxythiophene (PEDOT) for the purpose of selectively quantifying peroxynitrite. The nanostructured modified polymer layer was characterized by Raman spectroscopy and scanning electron microscopy (SEM). The electrochemical response to peroxynitrite was studied by voltammetry and time-based amperometry. The measured detection limit was 10 ± 0.5 nM (S/N = 3), the sensitivity was 4.5 ± 0.5 nA nM(-1) and the response time was 3.5 ± 1 s. The hemin-PEDOT BDD sensors exhibited a response variability of 5% or less (RSD). The stability of the sensors after a 20-day storage in 0.1 M PB (pH 7.4) at 4 °C was excellent as at least 93% of the initial response to 50 nM PON was maintained. The presence of PEDOT was correlated with a sensitivity increase.

Electronic Olfactory Sensor Based on A.†mellifera Odorant-Binding Protein†14 on a Reduced Graphene Oxide Field-Effect Transistor.

An olfactory biosensor based on a reduced graphene oxide (rGO) field-effect transistor (FET), functionalized by the odorant-binding protein 14 (OBP14) from the honey bee (Apis mellifera) has been designed for the in situ and real-time monitoring of a broad spectrum of odorants in aqueous solutions known to be attractants for bees. The electrical measurements of the binding of all tested odorants are shown to follow the Langmuir model for ligand-receptor interactions. The results demonstrate that OBP14 is able to bind odorants even after immobilization on rGO and can discriminate between ligands binding within a range of dissociation constants from K(d)=4 µM to K(d)=3.3 mM. The strongest ligands, such as homovanillic acid, eugenol, and methyl vanillate all contain a hydroxy group which is apparently important for the strong interaction with the protein.

Peroxynitrite activity of hemin-functionalized reduced graphene oxide.

Conducting interfaces modified with reduced graphene oxide (rGO) have shown improved electrochemical response for different analytes. The efficient formation of functionalized rGO based materials is thus of current interest for the development of sensitive and selective biosensors. Herein, we report a simple and environmentally friendly method for the formation of a hemin-functionalized rGO hybrid nanomaterial that exhibits remarkable sensitivity to peroxynitrite (ONOO(-)) in solution. The hemin-functionalized rGO hybrid nanomaterial was formed by mixing an aqueous solution of graphene oxide (GO) with hemin and sonicating the suspension for 5 h at room temperature. In addition to playing a key role in biochemical and electrocatalytic reactions, hemin has been proven to be a good reducing agent for GO. The sensitivity of the peroxynitrite sensor is ≈7.5 ± 1.5 nA mM(-1) with a detection limit of 5 ± 1.5 nM.

Exhaled breath biomarker sensing.

This goal of this minireview is to introduce the reader to the area of research concerned with exhaled breath analysis for the purpose of detecting abnormal levels of physiologically-relevant chemical markers reflective of respiratory diseases. Two main two groups of sensing methods are reviewed: mass spectrometry and (bio)sensors. The discussion focuses on biosensor applications for EB and EBC analyses, which are presented in detail. The review finishes with conclusions and future perspectives, including recommendations for future near-term and long-term development of EBC biomarker sensing.

Biochemical researches in age related cataract.

PURPOSE: To comparatively evaluate the biochemical profile in normal human lenses with capsule and in stages of age related opaque lenses without capsule. MATERIALS AND METHODS: The study included 3 groups of lenses with transparent structure, mature and incipient cataract. RESULTS: The results were for 25 biochemical investigations. CONCLUSIONS: Multiple biochemical mechanisms contribute to the progressive loss of transparency of the lens.

Effect of VEGFR, PDGFR and PI3K/mTOR Targeting in Glioblastoma.

Resistance to targeted therapy is a well known obstacle in cancer therapy. The cross-talk between several growth factor receptors generates redundancy in their intracellular pathways that usually mediates resistance to receptor targeted therapy. Simultaneous inactivation of two or more growth factor receptors has been suggested to prevent the cross-talk between their signaling pathways and to better eliminate malignant cells. Here we found that targeted therapy against these receptors induced moderate cell death in glioblastoma cells. More important, dual PDGFR and VEGFR inactivation induced more pronounceable cell death compared to inactivation of each receptor alone but failed to induce synergistic cell death in glioblastoma. PI3K/mTOR dual targeting has been identified as an efficient therapeutic approach in several malignant diseases, including glioblastoma. Therefore, we also investigated the PI3K/mTOR pathways inhibition effect in glioblastoma cells. Our results showed that inactivation of PI3K/mTOR pathways were more efficient than PDGFR or VEGFR single targeting or their dual inhibition.

Nitro-oxidative species in vivo biosensing: challenges and advances with focus on peroxynitrite quantification.

The importance of the so-called reactive nitrogen and oxygen species (RNOS) in biology and food technology has been widely recognized. However when these species are in excess, the steady-state maintained by physiological processes is disturbed. At this point, the nitro oxidative metabolic stress develops and its action in vivo over time leads to nitro-oxidative reactions in food and in living organisms, but also results in chronic degenerative diseases. Analytical methods enabling the assessment of the total antioxidant activity of a biological sample or a plant extract is therefore largely sought after. The ability of biosensors for rapid and real-time analysis that decreases the assay time and the possibility of automated and multi-analyte analysis at low cost has also allowed the quantitative and qualitative detection of RNOS. Among these RNOS, peroxynitrite (ONOO(-)) is a well-known inflammatory mediator during a number of physiological and pathological processes. Consequently, many efforts are underway to detect peroxynitrite in the biomedical field. This urgent demand makes the development of ONOO(-) specific probes of great interest. Not only they can be useful for the detection of disease states, but they will also allow for a screening-type analysis of potential signal transduction pathways in the cells. This invited review will critically discuss for the first time the very latest advancements and the challenges in the field of peroxynitrite biosensors and probes for in vivo and in vitro studies. Also, the main trends will be extracted, in order to chart the future directions and hence create an instrumental outlook.

Polymerized hemin as an electrocatalytic platform for peroxynitrite's oxidation and detection.

Peroxynitrite (ONOO(-)) constitutes a major cytotoxic agent, implicated in a host of pathophysiological conditions, thereby stimulating a tremendous interest in evaluating its role as an oxidant in vivo. Some of the detection methods for peroxynitrite include oxidation of fluorescent probes, EPR spectroscopy, chemiluminescence, immunohistochemistry, and probe nitration; however, these are more difficult to apply for real-time quantification due to their inherent complexity. The electrochemical detection of peroxynitrite is a simpler and more convenient technique, but the best of our knowledge there are only few papers to date studying its electrochemical signature, or reporting amperometric microsensors for peroxynitrite. Recently, we have reported the use of layered composite films of poly(3,4-ethylenedioxythiophene) (PEDOT) and hemin (iron protoporphyrin IX) as a platform for amperometric measurement of peroxynitrite. The main goal herein is to investigate the intrinsic catalytic role of hemin electropolymerized thin films on carbon electrodes in oxidative detection of peroxynitrite. The electrocatalytic oxidation of peroxynitrite is characterized by cyclic voltammetry. The catalytic current increased as a function of peroxynitrite's concentration, with a peak potential shifting positively with peroxynitrite's concentration. The catalytic efficiency decreased as the scan rate increased, and the peak potential of the catalytic oxidation was found to depend on pH. We show that optimized hemin-functionalized carbon electrodes can be used as simple platforms for peroxinitrite detection and quantification. We report dose-response amperometry as an electroanalytical determination of this analyte on hemin films and we contrast the intrinsic hemin catalytic role with its performance in the case of the PEDOT-hemin as a composite matrix. Finally, we include some work extending the use of simple hemin films for peroxynitrite determination on carbon microfiber electrodes in a flow system.

Actuation of polypyrrole nanowires.

Nanoscale actuators are essential components of the NEMS (nanoelectromechanical systems) and nanorobots of the future, and are expected to become a major area of development within nanotechnology. This paper demonstrates for the first time that individual polypyrrole (PPy) nanowires with diameters under 100 nm exhibit actuation behavior, and therefore can potentially be used for constructing nanoscale actuators. PPy is an electroactive polymer which can change volume on the basis of its oxidation state. PPy-based macroscale and microscale actuators have been demonstrated, but their nanoscale counterparts have not been realized until now. The research reported here answers positively the fundamental question of whether PPy wires still exhibit useful volume changes at the nanoscale. Nanowires with a 50 nm diameter and a length of approximately 6 µm, are fabricated by chemical polymerization using track-etched polycarbonate membranes as templates. Their actuation response as a function of oxidation state is investigated by electrochemical AFM (atomic force microscopy). An estimate of the minimum actuation force is made, based on the displacement of the AFM cantilever.

[Glutathione, a biochemical indicator for different types of cellular oxidative stress. II. Ethanol poisoning]. / Glutationul, indicator biochimic pentru diferite tipuri de stress oxidativ celular. Nota II: Intoxicatia cu etanol.

Eight male volunteers, all alcohol addicts selected from the patients of the Padureni unit, deprived for a minimum of two weeks of alcohol, but with an at least 2-year history of alcohol addiction, received 0.5 ml absolute alcohol/kg body weight. Following dynamically the alteration of plasma reduced glutathione content, a significant increase (+8.27%) 30 minutes after alcohol ingestion and a decrease (-7.02%) before ingestion, as compared to plasma glutathione level in sex and age-matched clinically normal subject (100%) was noticed. The change in the --SH groups content in plasma after chronic alcohol ingestion leads to the occurrence of cell oxidative stress, as well as to a decreased resistance of hepatic cell and whole body as a result of the lipid peroxidation process and/or occurrence of detrimental reactive radical species, issuing from O2.

[Interventions associated with some risk factors for essential arterial hypertension. I. Epidemiologic observations in adults]. / Interventia asociativa a unor factori de risc pentru hipertensiunea arteriala esentiala. I. Observatii epidemiologice la adulti.

The results of an epidemiological screening followed by the investigation of 9 risk factors for essential hypertension in 1218 individuals with increased values of blood pressure are presented. Stress, overweight and dietary preferences for fats and eggs had the incidence especially in, the age groups over 40 years. Both the individuals with borderline hypertension or arterial hypertension and the controls presented 2, 3 or more associated risk factors of variable intensity, the higher values being recorded in the greater than or equal to 40 years age group. When more than 3 risk factors were associated, the increases in systolic and diastolic pressures were significant. The investigation of 7 biochemical constants revealed that 50% of 190 cases with arterial hypertension presented cholesterol levels higher than 220 mg%. Increased total lipids, free fatty acids and triglycerides levels were also recorded. The results plead for multifactorial prevention programmes.

[Glutathione and the redox index in different types of cellular oxidative stress. I. Acrylonitrile (ACN) poisoning]. / Glutationul si indexul redox in diferite tipuri de stres oxidativ celular. I. Intoxicatia cu acrilonitril (ACN).

The professional poisoning with acrylonitrile of some subjects induced a significant decrease of reduced glutathione (81.30%), redox ratio reduced glutathione/oxidized glutathione (90.74%) and "Benzi-redox index" (55.84%) but an increase of oxidized glutathione level (112.6%) as compared to normal controls (100%). This proves the occurrence, in time, of the cellular oxidative stress and/or were obtained.

[The dynamics of ethanol metabolism in patients with chronic alcoholism]. / Dinamica metabolizarii etanolului, referinte cazuistice la bolnavii cu etilism cronic.

The results of the investigations carried out in alcoholics and nonalcoholics regarding certain aspects of ethanol metabolism are presented. The marked interindividual differences in alcohol blood levels and intergroup differences in acetaldehyde levels, through a projection in dynamic process, are commented upon. The programmed ethanolic load induced changes in blood alcohol, within comparable limits, irrespective of subjects' state. At all intervals of postintake determinations, the acetaldehyde concentrations were higher in the alcoholic subjects. No dose-effect relation between the involved elements (ethanol metabolite) was found.

[Intervention associated with risk factors for essential arterial hypertension. II. Epidemiologic observations of schoolchildren]. / Interventia asociativa a unor factori de risc pentru hipertensiunea arteriala esentiala. II. Observatii epidemiologice la scolari.

Based on an epidemiological screening of 6411 pupils from 7 schools of different types, the frequency and intensity of the association of 8 risk factors for essential hypertension in a series with increased blood pressure values and in a normotensive one was compared. The frequency of the various studied risk factors was significant especially in the pupils with increased blood pressure values. The average number of risk factors in the two series was unsignificant. The intensity of 2, 3 or 4 risk factors different associations was more marked in the pupils with increased blood pressure values than in the controls. Some risk factors proved to be more frequently involved in multifactorial associations. The importance of such studies for the elaboration of prevention programmes in underlined.

[Epidemiology of essential arterial hypertension in collectives of schoolchildren. The prevalence of blood pressure changes]. / Unele aspecte din epidemiologia hipertensiunii arteriale esentiale în colectivitati scolare. Prevalenta modificarilor tensiunii arteriale.

7,917 pupils in schools, between 10-19 years old, of both sexes, were investigated within an epidemiologic screening, performed in the school milieu, for detecting the prevalence of some risk factors (RF) and of the AT modifications with a view to work out the programmes for the essential arterial hypertension (EAHT) primary prevention. 84.4% of all the pupils in the Vth--VIIIth forms and 93.9 pupils in the IXth--XIIth forms were included in the screening. 422 cases of labile arterial hypertension (LAHT) (5.1%) and 457 of benign arterial hypertension (BATH) (54%) were found. In the children with normal arterial hypertension (NAHT) the following were recorded: 46.5% increases only of the diastolic tension: 44.0% of the systolic-diastolic and 7.1% of the systolic tension respectively. Although present, the differences between the LAHT and BAHT prevalence in the gymnasiums (4.3% and 5.4%) and lyceums (5.5% and 6.4%) are not significant and might be functions of: age, sex, psychomotor development, structure of the respective collectivities, the momentary psychoemotional reactions, lability of the blood pressure, specific to the childhood, several screening difficulties etc. The observations made on the prevalence of the growth of the AT values were correlated with the occurrence at some significant levels of the RF, suggesting the measures to be taken for the steady improvement of the primary and secondary prophylaxis of EAHT in schools.

Polymerized crystalline colloidal array chemical-sensing materials for detection of lead in body fluids.

We have developed intelligent polymerized crystalline colloidal array (IPCCA) chemical-sensing materials for detection of Pb(2+) in high ionic-strength environments such as body fluids with a detection limit of <500 nmol L(-1) Pb(2+) (100 ppb). This IPCCA lead sensor consists of a mesoscopically periodic array of colloidal particles polymerized into an acrylamide hydrogel. The array Bragg-diffracts light in the visible spectral region because of the periodic spacing of the colloidal particles. This material also contains a crown ether chelating agent for Pb(2+). Chelation of Pb(2+) by the IPCCA in low-ionic-strength solutions results in a Donnan potential that swells the gel, which red-shifts the diffracted light in proportion to the Pb(2+) concentration. At high ionic strength the Donnan potential is, unfortunately, swamped and no static response occurs for these sensors. We demonstrate, however, that we can determine Pb(2+) at high ionic strength by incubating these IPCCA in a sample solution and then measuring their transient response on exposure to pure water. The non-complexed ions diffuse from the IPCCA faster than the bound Pb(2+). The resulting transient IPCCA diffraction red-shift is proportional to the concentration of Pb(2+) in the sample. These IPCCA sensors can thus be used as sensing materials in optrodes to determine Pb(2+) in high-ionic-strength solutions such as body fluids.