Biosensor for the oxidative stress biomarker glutathione based on SAM of cobalt phthalocyanine on a thioctic acid modified gold electrode

International audienceSelf-assembled monolayer (SAM) of cobalt teraaminophthalocyanine (CoTAPc) was developed on thioctic acid (TA) dithiol modified gold electrode and electrochemically evaluated as a glutathione (GSH) selective biosensor. The CoTAPc-TA-Au modified electrode was developed by the covalent immobilization of the CoTAPc as the electrochemical mediator onto previously prepared gold electrode modified with TA (TA-Au) via amid bond formation with the carboxylic group of TA, producing well-organized SAM of the mediator. For comparison, another electrode modified with 3-mercaptopropionic acid (MPA) as a monothiol linker instead of TA was similarly prepared. The electrode surface modification was characterized using SEM, AFM, CV, and EIS. The contact angle measurements of the surface confirmed the formation of CoTAPc SAM on both TA and MPA modified electrodes. The CoTAPc-TA-Au modified electrode showed enhanced catalytic activity for GSH oxidation compared to that of CoTAPc-MPA-Au, indicating that the TA dithiol allowed for more coverage of the catalyst layer on the electrode surface with stronger binding. The experimental parameters controlling the voltammetric processes like scan rate and pH of sample solution were optimized. Using DPV technique, the proposed sensor exhibited a linear response of oxidation peak current vs. GSH concentration, over the concentration range between 10 and 100molL(-1) with a LOD of 1.5molL(-1) for the CoTAPc-TA-Au modified electrode compared to 5.5molL(-1) GSH, for the CoTAPc-MPA-Au electrode. The proposed sensor was utilized for detection of glutathione in some hemolyzed blood samples

Novel iron (III) phthalocyanine derivative functionalized semiconductor based transducers for the detection of citrate

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Spatially hierarchical nano-architecture for real time detection of Interleukin-8 cancer biomarker

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Development of a capacitive chemical sensor based on Co(II)-phthalocyanine acrylate-polymer/HfO2/SiO2/Si for detection of perchlorate

International audienceWe report the development of a chemical sensor based on a Co(II) phthalocyanine acrylate polymer (Co(II)Pc-AP) for perchlorate anion detection. We have used two types of transducers, silicon nitride (Si3N4) and hafnium oxide (HfO2). The adhesion of the Co(11)Pc-AP on different transducers and their surface qualities have been studied by contact angle measurements. We haNe studied the pH effect on AllSi/SiO2/HfO2/electrolyte capacitance values for different phosphate buffer solutions (PBS). This optimization step has allowed a sensitivity value of about 44 mV decade-1 towards H+ ions. The fabricated sensors based on Si3N4 and HfO2 transducers functionalized with a Co(11)Pc-AP membrane have been characterized by C(V) measurements for different perchlorate concentrations (from 10-7 to 10-2M). The sensor developed with the HfO2 transducer shows better performances compared to that based on Si3N4: a larger detection range (10(-7) to 10(-2) and 10(-3) to 10(-2) M, respectively) and lower detection limits (10-7 and 10(-3) M). The specificities of our perchlorate sensor have been tested for some interfering ions (nitrate, sulfate and carbonate)

A novel chronoamperometric immunosensor for rapid detection of TNF-α in human saliva

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Ultrasensitive Immunosensor Array for TNF-α Detection in Artificial Saliva using Polymer-Coated Magnetic Microparticles onto Screen-Printed Gold Electrode

Tumor necrosis factor-α (TNF-α) is a biomarker of inflammation that occurs in patients suffering from heart failure (HF). Saliva can be sampled in a non-invasive way, and it is currently gaining importance as matrix alternative to blood in diagnostic and therapy monitoring. This work presents the development of an immunosensor array based on eight screen-printed gold electrodes to detect TNF-α in saliva samples. Two different functionalization strategies of electrodes were compared. In the first, anti-TNF-α antibodies were chemically bonded onto the electrode by functionalization with 4-carboxymethylaniline. The other functionalization procedure involved the binding of antibodies onto polymer-coated magnetic microparticles, which were then deposited onto the electrode by pulsed chronoamperometry. Finally, the chronoamperometry technique was applied to characterize the modified SPEAu. The use of a secondary antibody anti-TNF-α (Ab-TNF-α-HRP) labelled with horseradish peroxidase (HRP, 2 µg·mL−1) was investigated using tetramethylbenzidine (TMB, pH = 3.75) as electrochemical substrate containing 0.2 mM of H2O2. A sandwich-type detection strategy with a secondary antibody anti-TNF-α provided chronoamperometric analyses in 10 s for each sample. Linearity, precision, limit of detection, and selectivity of devices were investigated. Interferences were evaluated by analyzing solutions containing other cytokine produced during the acute stage of inflammation. The immunosensor showed good performance within the clinically relevant concentration range, with a precision of 8%, and a limit of detection of 0.3 pg/mL. Therefore, it may represent a promising tool for monitoring HF in a non-invasive way

Capacitance Electrochemical pH Sensor Based on Different Hafnium Dioxide (HfO2) Thicknesses

© 2021 by the authors.Over the past years, to achieve better sensing performance, hafnium dioxide (HfO2) has been studied as an ion-sensitive layer. In this work, thin layers of hafnium dioxide (HfO2) were used as pH-sensitive membranes and were deposited by atomic layer deposition (ALD) process onto an electrolytic-insulating-semiconductor structure Al/Si/SiO2/HfO2 for the realization of a pH sensor. The thicknesses of the layer of the HfO2 studied in this work was 15, 19.5 and 39.9 nm. HfO2 thickness was controlled by ALD during the fabrication process. The sensitivity toward H+ was clearly higher when compared to other interfering ions such as potassium K+, lithium Li+, and sodium Na+ ions. Mott−Schottky and electrochemical impedance spectroscopy (EIS) analyses were used to characterise and to investigate the pH sensitivity. This was recorded by Mott–Schottky at 54.5, 51.1 and 49.2 mV/pH and by EIS at 5.86 p[H−1], 10.63 p[H−1], 12.72 p[H−1] for 15, 19.5 and 30 nm thickness of HfO2 ions sensitive layer, respectively. The developed pH sensor was highly sensitive and selective for H+ ions for the three thicknesses, 15, 19.5 and 39.9 nm, of HfO2-sensitive layer when compared to the other previously mentioned interferences. However, the pH sensor performances were better with 15 nm HfO2 thickness for the Mott–Schottky technique, whilst for EIS analyses, the pH sensors were more sensitive at 39.9 nm HfO2 thickness.Funding through the European Union’s Horizon 2020 research and innovation program entitled “An integrated POC solution for non-invasive diagnosis and therapy monitoring of Heart Failure patients, KardiaTool” under grant agreement No 768686.Peer reviewe

Epidemiology of heart failure and long-term follow-up outcomes in a north-African population: Results from the NAtional TUnisian REgistry of Heart Failure (NATURE-HF)

International audienceThe NATURE-HF registry was aimed to describe clinical epidemiology and 1-year outcomes of outpatients and inpatients with heart failure (HF). This is a prospective, multicenter, observational survey conducted in Tunisian Cardiology centers. A total of 2040 patients were included in the study. Of these, 1632 (80%) were outpatients with chronic HF (CHF). The mean hospital stay was 8.7 ± 8.2 days. The mortality rate during the initial hospitalization event for AHF was 7.4%. The all-cause 1-year mortality rate was 22.8% among AHF patients and 10.6% among CHF patients. Among CHF patients, the older age, diabetes, anemia, reduced EF, ischemic etiology, residual congestion and the absence of ACEI/ ARBs treatment were independent predictors of 1-year cumulative rates of rehospitalization and mortality. The female sex and the functional status were independent predictors of 1-year all-cause mortality and rehospitalization in AHF patients. This study confirmed that acute HF is still associated with a poor prognosis, while the mid-term outcomes in patients with chronic HF seems to be improved. Some differences across countries may be due to different clinical characteristics and differences in healthcare systems

Design and Rationale of the National Tunisian Registry of Heart Failure (NATURE-HF): Protocol for a Multicenter Registry Study

BackgroundThe frequency of heart failure (HF) in Tunisia is on the rise and has now become a public health concern. This is mainly due to an aging Tunisian population (Tunisia has one of the oldest populations in Africa as well as the highest life expectancy in the continent) and an increase in coronary artery disease and hypertension. However, no extensive data are available on demographic characteristics, prognosis, and quality of care of patients with HF in Tunisia (nor in North Africa). ObjectiveThe aim of this study was to analyze, follow, and evaluate patients with HF in a large nation-wide multicenter trial. MethodsA total of 1700 patients with HF diagnosed by the investigator will be included in the National Tunisian Registry of Heart Failure study (NATURE-HF). Patients must visit the cardiology clinic 1, 3, and 12 months after study inclusion. This follow-up is provided by the investigator. All data are collected via the DACIMA Clinical Suite web interface. ResultsAt the end of the study, we will note the occurrence of cardiovascular death (sudden death, coronary artery disease, refractory HF, stroke), death from any cause (cardiovascular and noncardiovascular), and the occurrence of a rehospitalization episode for an HF relapse during the follow-up period. Based on these data, we will evaluate the demographic characteristics of the study patients, the characteristics of pathological antecedents, and symptomatic and clinical features of HF. In addition, we will report the paraclinical examination findings such as the laboratory standard parameters and brain natriuretic peptides, electrocardiogram or 24-hour Holter monitoring, echocardiography, and coronarography. We will also provide a description of the therapeutic environment and therapeutic changes that occur during the 1-year follow-up of patients, adverse events following medical treatment and intervention during the 3- and 12-month follow-up, the evaluation of left ventricular ejection fraction during the 3- and 12-month follow-up, the overall rate of rehospitalization over the 1-year follow-up for an HF relapse, and the rate of rehospitalization during the first 3 months after inclusion into the study. ConclusionsThe NATURE-HF study will fill a significant gap in the dynamic landscape of HF care and research. It will provide unique and necessary data on the management and outcomes of patients with HF. This study will yield the largest contemporary longitudinal cohort of patients with HF in Tunisia. Trial RegistrationClinicalTrials.gov NCT03262675; https://clinicaltrials.gov/ct2/show/NCT03262675 International Registered Report Identifier (IRRID)DERR1-10.2196/1226