NEW MODIFIED ELECTRODES WITH HRP IMMOBILIZED IN POLYMERIC FILMS FOR PARACETAMOL ANALYSIS

Abstract In order to establish the configurations of biosensors that are able to detect paracetamol in various matrices, it was studied the behaviour of some modified electrodes with an electroconductive polymeric film. Polypyrrole films deposition on glassy carbon and screen-printed electrodes was developped by several methods. The electroanalytical characterization of the deposited films was performed by chronoamperometry in the presence of an enzyme immobilized into the polymeric films. Chronoamperometric study performed with glassy carbon and planar electrodes based on graphite, modified with horseradish peroxidase embedded in polypyrrole films, proved the existence of interactions between the immobilized enzyme and the electroactive species of paracetamol (N-acetyl-p-benzo-quinone imine-NAPQI), enzymatically generated in the presence of hydrogen peroxide. Rezumat În vederea elaborării unor biosenzori capabili să detecteze paracetamolul din diferite matrici a fost studiat comportamentul electrozilor modificați cu filme electroconductoare de polipirol. Depunerea filmelor de polipirol pe suprafața electrozilor de carbon vitros și electrozilor planari imprimați a fost realizată prin mai multe metode. Caracterizarea electroanalitică a filmelor depuse a fost realizată prin cronoamperometrie, în prezența enzimei imobilizate la nivelul filmelor polimerice. Studiile de cronoamperometrie efectuate pe ambele tipuri de electrozi modificați cu peroxidaza din hrean, incorporată în filmul de polipirol, au demonstrat existența intercțiunilor între enzima imobilizată și speciile electroactive ale paracetamolului (Nacetil-p-benzo-chinon imina-NAPQI), generate enzimatic în prezența peroxidului de hidrogen

Micro- to nanostructured poly(pyrrole-nitrilotriacetic acid) films via nanosphere templates: applications to 3D enzyme attachment by affinity interactions

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The completion of the mathematical model by parameter identification for simulating a turbofan engine

The purpose of this paper is to set up a method to determine the missing engine design parameters (turbine inlet temperature T3T, airflow rate) which significantly influence the jet engines thrust. The authors have introduced a new non-linear equation connecting the fan specific work with the temperature T3T, customized for turbofan. The method of chords, since it converges unconditionally, has been used for solving the non-linear equation of variable temperature T3T. An alternate method, based for the same relation between fan specific work and T3T, has been presented in purpose to determine airflow rate and fan pressure ratio. Two mixed flows turbofans have been considered as study cases. For case #1 it was determined a value comparable to the Turbomeca Larzac turbofan series 04-C6 and 04-C20 which power the AlphaJet machines (series A - Luftwaffe, series E - Dassault Dornier). For the F100-PW229 turbofan, as case #2, being given T3T, then have been determined the airflow rate, fan pressure ratio and fan specific work. After completing the mathematical model with the missing parameters, the performances of the engines at off-design regimes and the operational envelopes revealing i.e. the variations of thrust, specific thrust and fuel specific consumption with altitude and Mach number have been calculated

Electrochemical Peptide-Based Sensors for Foodborne Pathogens Detection

Food safety and quality control pose serious issues to food industry and public health domains, in general, with direct effects on consumers. Any physical, chemical, or biological unexpected or unidentified food constituent may exhibit harmful effects on people and animals from mild to severe reactions. According to the World Health Organization (WHO), unsafe foodstuffs are especially dangerous for infants, young children, elderly, and chronic patients. It is imperative to continuously develop new technologies to detect foodborne pathogens and contaminants in order to aid the strengthening of healthcare and economic systems. In recent years, peptide-based sensors gained much attention in the field of food research as an alternative to immuno-, apta-, or DNA-based sensors. This review presents an overview of the electrochemical biosensors using peptides as molecular bio-recognition elements published mainly in the last decade, highlighting their possible application for rapid, non-destructive, and in situ analysis of food samples. Comparison with peptide-based optical and piezoelectrical sensors in terms of analytical performance is presented. Methods of foodstuffs pretreatment are also discussed

Click chemistry on azide-functionalized graphene oxide

Chemical functionalization of graphene oxide represents a major challenge in chemical engineering with the aim of both improving the properties of the material while generating versatile platforms with a broad range of applications. The development of electrochemical (bio)sensors requires the controlled and rational immobilization of molecules as a key step in the enhancement of analytical performance. Click chemistry reactions represent an important strategy for the covalent linking of different compounds on a substrate via complementary azide or alkyne groups. The mild reaction conditions allow the preservation of the properties of biomolecules, while the orientation towards green chemistry enables a new range of biomedical applications. The azide group was inserted in the graphene oxide backbone by chemical functionalization and the resulting product was characterized by Fourier-transform infrared spectroscopy, scanning electron microscopy and electrochemical impedance spectroscopy. The successful synthesis of the graphene-azide platform was also validated by electrochemical methods performed after clicking ethynylferrocene, an electroactive model molecule. The results show that this new approach is a versatile method for the covalent immobilization of biomolecules. Keywords: Graphene oxide, Azide, Click chemistry, Electrochemical methods, Ethynylferrocen

A Nanocomposite Based on Reduced Graphene and Gold Nanoparticles for Highly Sensitive Electrochemical Detection of <i>Pseudomonas aeruginosa</i> through Its Virulence Factors

Pyoverdine is a fluorescent siderophore produced by Pseudomonas aeruginosa that can be considered as a detectable marker in nosocomial infections. The presence of pyoverdine in water can be directly linked to the presence of the P. aeruginosa, thus being a nontoxic and low-cost marker for the detection of biological contamination. A novel platform was developed and applied for the electrochemical selective and sensitive detection of pyoverdine, based on a graphene/graphite-modified screen-printed electrode (SPE) that was electrochemically reduced and decorated with gold nanoparticles (NPs). The optimized sensor presenting higher sensitivity towards pyoverdine was successfully applied for its detection in real samples (serum, saliva, and tap water), in the presence of various interfering species. The excellent analytical performances underline the premises for an early diagnosis kit of bacterial infections based on electrochemical sensors