Effect of Benzotriazole Derivatives on Steel Corrosion in Solution Simulated Carbonated Concrete

The aim of this research was to develop corrosion protection systems for reinforced concrete structures under carbonation attack. Benzotriazole (BTA) and BTA derivatives were used as two separate protection systems: inhibition and pickling protection systems. The experiments were performed in Simulated Concrete Pore (SCP) solutions with and without severe carbonation attack. Electrochemical techniques, i.e. potentiodynamic polarization and electrochemical impedance were used to assess the steel corrosion protection systems. The potentiodynamic polarization studies showed a reduction in the corrosion rate and a shifting in the corrosion potential to more noble potential for the steel specimen in the simulated carbonated concrete solution. In addition, a large increase in the steel interfacial resistance was observed by Electrochemical Impedance Studies (EIS) due to the formation of steel-BTA derivative complex on the surface. BTA derivatives provided a good protection for the steel in SCP simulated carbonated concrete solutions. This study indicates the applicability of these compounds for steel corrosion protection in reinforced concrete structures

Lethality of MalE-LacZ hybrid protein shares mechanistic attributes with oxidative component of antibiotic lethality

Downstream metabolic events can contribute to the lethality of drugs or agents that interact with a primary cellular target. In bacteria, the production of reactive oxygen species (ROS) has been associated with the lethal effects of a variety of stresses including bactericidal antibiotics, but the relative contribution of this oxidative component to cell death depends on a variety of factors. Experimental evidence has suggested that unresolvable DNA problems caused by incorporation of oxidized nucleotides into nascent DNA followed by incomplete base excision repair contribute to the ROS-dependent component of antibiotic lethality. Expression of the chimeric periplasmic-cytoplasmic MalE-LacZ[subscript 72 – 47] protein is an historically important lethal stress originally identified during seminal genetic experiments that defined the SecY-dependent protein translocation system. Multiple, independent lines of evidence presented here indicate that the predominant mechanism for MalE-LacZ lethality shares attributes with the ROS-dependent component of antibiotic lethality. MalE-LacZ lethality requires molecular oxygen, and its expression induces ROS production. The increased susceptibility of mutants sensitive to oxidative stress to MalE-LacZ lethality indicates that ROS contribute causally to cell death rather than simply being produced by dying cells. Observations that support the proposed mechanism of cell death include MalE-LacZ expression being bacteriostatic rather than bactericidal in cells that over-express MutT, a nucleotide sanitizer that hydrolyzes 8-oxo-dGTP to the monophosphate, or that lack MutM and MutY, DNA glycosylases that process base pairs involving 8-oxo-dGTP. Our studies suggest stress-induced physiological changes that favor this mode of ROS-dependent death.National Institutes of Health (U.S.) (Grant R01CA021615)Defense Threat Reduction Agency (DTRA) (Grant HDTRA1-15-1-0051)National Science Foundation (U.S.) (Grant 1336493)National Institutes of Health (U.S.) (Grant K99GM118907

Magnetic Particle-Based Hybrid Platforms for Bioanalytical Sensors

Biomagnetic nano and microparticles platforms have attracted considerable interest in the field of biological sensors due to their interesting physico-chemical properties, high specific surface area, good mechanical stability and opportunities for generating magneto-switchable devices. This review discusses recent advances in the development and characterization of active biomagnetic nanoassemblies, their interaction with biological molecules and their use in bioanalytical sensors

Chemical and Biological Sensors for Food-Quality Monitoring and Smart Packaging

The growing interest in food quality and safety requires the development of sensitive and reliable methods of analysis as well as technology for freshness preservation and food quality. This review describes the status of chemical and biological sensors for food monitoring and smart packaging. Sensing designs and their analytical features for measuring freshness markers, allergens, pathogens, adulterants and toxicants are discussed with example of applications. Their potential implementation in smart packaging could facilitate food-status monitoring, reduce food waste, extend shelf-life, and improve overall food quality. However, most sensors are still in the development stage and need significant work before implementation in real-world applications. Issues like sensitivity, selectivity, robustness, and safety of the sensing materials due to potential contact or migration in food need to be established. The current development status of these technologies, along with a discussion of the challenges and opportunities for future research, are discussed

MXenes-Based Bioanalytical Sensors: Design, Characterization, and Applications

MXenes are recently developed 2D layered nanomaterials that provide unique capabilities for bioanalytical applications. These include high metallic conductivity, large surface area, hydrophilicity, high ion transport properties, low diffusion barrier, biocompatibility, and ease of surface functionalization. MXenes are composed of transition metal carbides, nitrides, or carbonitrides and have a general formula Mn+1Xn, where M is an early transition metal while X is carbon and/or nitrogen. Due to their unique features, MXenes have attracted significant attention in fields such as clean energy production, electronics, fuel cells, supercapacitors, and catalysis. Their composition and layered structure make MXenes attractive for biosensing applications. The high conductivity allows these materials to be used in the design of electrochemical biosensors and the multilayered configuration makes them an efficient immobilization matrix for the retention of activity of the immobilized biomolecules. These properties are applicable to many biosensing systems and applications. This review describes the progress made on the use and application of MXenes in the development of electrochemical and optical biosensors and highlights future needs and opportunities in this field. In particular, opportunities for developing wearable sensors and systems with integrated biomolecule recognition are highlighted

Portable Nanoparticle-Based Sensors for Food Safety Assessment

The use of nanotechnology-derived products in the development of sensors and analytical measurement methodologies has increased significantly over the past decade. Nano-based sensing approaches include the use of nanoparticles (NPs) and nanostructures to enhance sensitivity and selectivity, design new detection schemes, improve sample preparation and increase portability. This review summarizes recent advancements in the design and development of NP-based sensors for assessing food safety. The most common types of NPs used to fabricate sensors for detection of food contaminants are discussed. Selected examples of NP-based detection schemes with colorimetric and electrochemical detection are provided with focus on sensors for the detection of chemical and biological contaminants including pesticides, heavy metals, bacterial pathogens and natural toxins. Current trends in the development of low-cost portable NP-based technology for rapid assessment of food safety as well as challenges for practical implementation and future research directions are discussed

Biocapteurs à acétylcholinestérase pour la détection sensible et spécifique des insecticides organophosphorés

Ce travail a pour objet la mise au point d'une électrode sérigraphiée à usage unique, basée sur l'acétylcholinestérase (AChE) et utilisable pour la détection des insecticides organophosphorés. Deux objectifs ont été définis: l'immobilisation de l'AchE sur les électrodes sérigraphiées et la détection des insecticides en présence de solvants organiques. Dans un premier temps, le travail a été orienté sur la mise au point de nouvelles méthodes d'immobilisation, basé sur le principe d'affinité pour les ions métalliques. Les différentes étapes ont été : la fonctionnalisation de l'électrode de travail, l'optimisation des conditions d'immobilisation. Les caractéristiques analytiques des biocapteurs obtenus ont été discutées. Les biocapteurs mis au point ont servi à la détection des insecticides organophosphorés suivants : paraoxon, dichlorvos, chlorpyriphos éthyle avec une limite de détection de l'ordre de 1 à quelques ppb. Dans une deuxième phase, les biocapteurs ont été utilisés pour la détection des insecticides en présence de solvants organiques. Deux systèmes ont été étudiés : un système mono-enzymatique en utilisant comme substrat le p-aminophényl acétate et le deuxième, un système bi-enzymatique AChE/ tyrosinase avec le phényle acétate comme substrat. Ces capteurs ont été utilisés pour la détection des insecticides en présence de faibles concentrations de solvants organiques miscibles à l'eau comme l'éthanol et l'acétonitrile.This work was focused on the development of a disposable acetylcholinesterase (AChE) screen printed sensor for the determination of organophosphorus insecticides. Two main directions have been followed during this study: the AChE immobilization on screen-printed electrodes and the detection of pesticides in presence of organic solvents.In a first approach, the work was focused on the finding new immobilization method compatible with screen printing technique which allows controlled and oriented attachment of AChE in a stable manner with a minimum loss of activity. The immobilization method based on the principle of metal chelate affinity was thus developed. The fonctionnalization of the graphite working electrode, the optimization of the working conditions and the analytical characteristics were discussed. The developed sensors exhibit good characteristics and they have been used for the determination of organophosphorus insecticides such as paraoxon, dichlorvos and chlorpyriphos ethyl oxon with a detection limit in the range of ppb.In a second approach, the AChE screen-printed sensors have been applied to detect pesticides in the presence of organic solvents. Two systems have been studied: a mono enzymatic AChE system using p-amino phenyl acetate as substrate and a bi-enzymatic system AChE/tyrosinase with phenyl acetate as substrate. The influence of organic solvents on the activity of immobilized AChE was evaluated and then, according to the results, the sensors were applied to the detection of pesticides in the presence of low amounts of water miscible organic solvents such as acetonitrile and ethanol.PERPIGNAN-BU Sciences (661362101) / SudocSudocFranceF