Electrochemical Antigenic Sensor for the Diagnosis of Chronic Q Fever

In this work, we report the development of an impedimetric biosensor for the direct, quick, and easy diagnosis of chronic Q fever. The biosensor is based on highly sensitive antigens that can selectively recognize antibodies against Coxiella burnetii. The biosensor is based on the immobilization of antigens onto a gold electrode using the EDC/NHS immobilization methodology. The detection is performed by impedance spectroscopy that monitors specific frequencies which provide the maximum sensitivity for the biosensor. Q fever antibodies that are present in the sera of patients interact selectively with the biosensor antigens, thereby altering the impedance of the biosensor surfaceand generating a large impedance change within a few seconds. The biosensor allows for the specific serological detection of chronic Q fever, while the developed system can also be modified for the detection of other biomarkers, such as the ones against acute Q fever

Direct electrochemical flow analysis system for simultaneous monitoring of total ammonia and nitrite in seawater

Abstract The design and the performance of a new portable flow analysis (FA) system for the continuous, fast and accurate measurement of total ammonia and nitrite content in nonfiltered seawater samples is demonstrated. The complete system has been optimized to operate within the ammonia and nitrite concentration range of 0.05 -10 ppm. The system offers good reproducibility ( B 5%) and stability ( B0.02 ppm/h) at constant temperature, while the analysis time is in the order of 1.5 -4 min depending on the sample analyzed. The analysis results of seawater samples obtained with the FA system were compared to that obtained with the standard colorimetric method and establish the suitability of the analyzer for the precise and continuous measurements of untreated samples for both in field and laboratory applications. In addition, its small size and weight offer the advantage of portability, while its datalogging capabilities also allow for independent ammonia and nitrite monitoring. © 2000 Elsevier Science B.V. All rights reserved

Components of all-solid-state ion-selective electrodes

An electrochemical sensor is a qualitative and quantitative device that converts a chemical signal to a measurable electrical signal (Yogeswaran and Shen-Ming 2008). Electrochemical sensors can be divided into three classes: potentiometric, amperometric, and conductometric (Stradiotto et al. 2003). A potentiometric sensor measures an electrical potential when no current is present, while an amperometric sensor produces current when a potential is applied between two electrodes. A conductometric sensor assesses conductivity by measuring the electrical resistance of a sample solution. Ion-selective electrodes (ISEs) are potentiometric ion sensors and a subgroup of electrochemical sensors; they are widely used in various fields of biomedical, environmental, and chemical analysis, and physiological sensing (Bobacka et al. 2003; Bakker et al. 2008; Hu et al. 2016). ISEs are classified into three groups, depending on the nature of the membrane material: glass, polymeric or liquid, and crystal or solid (Fig. 16.1) (Faridbod et al. 2007)