Abdoullatif Baraket

Highly sensitive electrochemical biosensor for bisphenol A detection based on a diazonium-functionalized boron-doped diamond electrode modified with a multi-walled carbon nanotube-tyrosinase hybrid film

A highly sensitive electrochemical biosensor for the detection of Bisphenol A (BPA) in water has been developed by immobilizing tyrosinase onto a diazonium-functionalized boron doped diamond electrode (BDD) modified with multi-walled carbon nanotubes (MWCNTs). The fabricated biosensor exhibits excellent electroactivity towards o-quinone, a product of this enzymatic reaction of BPA oxidation catalyzed by tyrosinase. The developed BPA biosensor displays a large linear range from 0.01 nM to 100 nM, with a detection limit (LOD) of 10 pM. The feasibility of the proposed biosensor has been demonstrated on BPA spiked water river samples. Therefore, it could be a promising and reliable analytical tool for on-site monitoring of BPA in waste water.

A fully integrated electrochemical biosensor platform fabrication process for cytokines detection.

Interleukin-1b (IL-1b) and interleukin-10 (IL-10) biomarkers are one of many antigens that are secreted in acute stages of inflammation after left ventricle assisted device (LVAD) implantation for patients suffering from heart failure (HF). In the present study, we have developed a fully integrated electrochemical biosensor platform for cytokine detection at minute concentrations. Using eight gold working microelectrodes (WEs) the design will increase the sensitivity of detection, decrease the time of measurements, and allow a simultaneous detection of varying cytokine biomarkers. The biosensor platform was fabricated onto silicon substrates using silicon technology. Monoclonal antibodies (mAb) of anti-human IL-1b and anti-human IL-10 were electroaddressed onto the gold WEs through functionalization with 4-carboxymethyl aryl diazonium (CMA). Cyclic voltammetry (CV) was applied during the WE functionalization process to characterize the gold WE surface properties. Finally, electrochemical impedance spectroscopy (EIS) characterized the modified gold WE. The biosensor platform was highly sensitive to the corresponding cytokines and no interference with other cytokines was observed. Both cytokines: IL-10 and IL-1b were detected within the range of 1pgmL-1 to 15pgmL-1. The present electrochemical biosensor platform is very promising for multi-detection of biomolecules which can dramatically decrease the time of analysis. This can provide data to clinicians and doctors concerning cytokines secretion at minute concentrations and the prediction of the first signs of inflammation after LVAD implantation.

Submicron magnetic core conducting polypyrrole polymer shell: Preparation and characterization

Magnetic particles are of great interest in various biomedical applications, such as, sample preparation, in vitro biomedical diagnosis, and both in vivo diagnosis and therapy. For in vitro applications and especially in labs-on-a-chip, microfluidics, microsystems, or biosensors, the needed magnetic dispersion should answer various criteria, for instance, submicron size in order to avoid a rapid sedimentation rate, fast separations under an applied magnetic field, and appreciable colloidal stability (stable dispersion under shearing process). Then, the aim of this work was to prepare highly magnetic particles with a magnetic core and conducting polymer shell particles in order to be used not only as a carrier, but also for the in vitro detection step. The prepared magnetic seed dispersions were functionalized using pyrrole and pyrrole-2-carboxylic acid. The obtained core-shell particles were characterized in terms of particle size, size distribution, magnetization properties, FTIR analysis, surface morphology, chemical composition, and finally, the conducting property of those particles were evaluated by cyclic voltammetry. The obtained functional submicron highly magnetic particles are found to be conducting material bearing function carboxylic group on the surface. These promising conducting magnetic particles can be used for both transport and lab-on-a-chip detection.

Novel strategy for sulfapyridine detection using a fully integrated electrochemical Bio-MEMS: Application to honey analysis.

Sulfapyridine (SPy) is a sulfonamide antibiotic largely employed as veterinary drugs for prophylactic and therapeutic purposes. Therefore, its spread in the food products has to be restricted. Herein, we report the synthesis and characterization of a novel electrochemical biosensor based on gold microelectrodes modified with a new structure of magnetic nanoparticles (MNPs) coated with poly(pyrrole-co-pyrrole-2-carboxylic acid) (Py/Py-COOH) for high efficient detection of SPy. This analyte was quantified through a competitive detection procedure with 5-[4-(amino)phenylsulfonamide]-5-oxopentanoic acid-BSA (SA2-BSA) antigens toward polyclonal antibody (Ab-155). Initially, gold working electrodes (WEs) of integrated biomicro electro-mechanical system (BioMEMS) were functionalized by Ppy-COOH/MNPs, using a chronoamperometric (CA) electrodeposition. Afterward, SA2-BSA was covalently bonded to Py/Py-COOH/MNP modified gold WEs through amide bonding. The competitive detection of the analyte was made by a mixture of a fixed concentration of Ab-155 and decreasing concentrations of SPy from 50µgL-1 to 2ngL-1. Atomic Force Microscopy characterization was performed in order to ensure Ppy-COOH/MNPs electrodeposition on the microelectrode surfaces. Electrochemical measurements of SPy detection were carried out using electrochemical impedance spectroscopy (EIS). This biosensor was found to be highly sensitive and specific for SPy, with a limit of detection of 0.4ngL-1. This technique was exploited to detect SPy in honey samples by using the standard addition method. The measurements were highly reproducible for detection and interferences namely, sulfadiazine (SDz), sulfathiazole (STz) and sulfamerazine (SMz). Taking these advantages of sensitivity, specificity, and low cost, our system provides a new horizon for development of advanced immunoassays in industrial food control.

A novel EIS field effect structures coated with TESUD-PPy-PVC-dibromoaza[7]helicene matrix for potassium ions detection.

In this work, we describe the development of new Aza[7]helicene-containing PVC-based membranes for the K(+) ions quantification. Here, silicon nitride-based structures (Si-p/SiO2/Si3N4) were developed and the surface was activated, functionalized with an aldehyde-silane (11-(Triethoxysilyl)undecanal (TESUD)), functionalized with polypyrrole (PPy), and coated with the polyvinylchloride (PVC)-membrane containing the Aza[7]helicene as ionophore. All stages of functionalization process have been thoroughly studied by contact angle measurements (CAMs) and atomic force microscopy (AFM). The developed ion-selective electrode (ISE) was then applied using electrochemical impedance spectroscopy (EIS) for the detection of potassium ions. A linear range was observed between 1.0 × 10(-8) M to 1.0 × 10(-3) M and a detection limit of 1.0 × 10(-8) M was observed. The EIS results have showed a good sensitivity to potassium ion using this novel technique. The target helicene exhibited good solubility and excellent thermal stability with a high decomposition temperature (Td > 300 °C) and it indicates that helicene may be a promising material as ionophore for ion-selective electrodes (ISEs) elaboration.

A low-cost and miniaturized potentiostat for sensing of biomolecular species such as TNF-α by electrochemical impedance spectroscopy

Miniaturizing potentiostats, keeping their cost low and yet preserving full measurement characteristics (e.g. bandwidth, determination of capacitive/inductive contribution to sensors impedance and parallel screening) is still an unresolved challenge in bioelectronics. In this work, the combination of simple analogue circuitry together with powerful microcontrollers and a digital filter implementation is presented as an alternative to complex and incomplete architectures reported in the literature. A low-cost acquisition electronic system fully integrated with a biosensors platform containing eight gold working microelectrodes and integrated reference and counter electrodes was developed and validated. The manufacturing cost of the prototype was kept below 300 USD. The performance of the proposed device was benchmarked against a commercial impedance analyzer through the electrochemical analysis of a highly sensitive biosensor for the detection of tumor necrosis factor α (TNF-α) within the randomly chosen range of 266pg/mL to 666ng/mL in physiological medium (PBS). A strong correlation between the outputs of both devices was found in a critical range of frequencies (1-10Hz), and several TNF-α cytokine concentrations were properly discriminated. These results are very promising for the development of low-cost, portable and miniaturized electrochemical systems for point-of-care and environmental diagnosis.

Electrochemical Biosensor for Interleukin-10 Detection in Real Human Plasma Patients: Heart Failure Biomedical Application

In the present study, we have analyzed the real human plasma effect for the detection of the cytokine biomarker; interleukin-10 (IL- 10) using an electrochemical impedance spectroscopy (EIS) based biosensor. IL-10 is one of the many antigens that are secreted in acute stages of inflammation after left ventricle assisted device (LVAD) implantation for patients suffering from heart failure (HF). For this interest, a biosensor was developed in order to increase the sensitivity of detection in complex medium and in the presence= of other interferences: interleukin-6 (IL-6) and interleukin-1 (IL-1) that are also secreted after LVAD implantation. The anti-human IL-10 monoclonal antibodies (anti-IL-10 mAb’s) were immobilized onto gold microelectrodes through functionalization with selfassembled monolayers (SAMs) of 16-Mercaptohexadecanoic acid b(MHDA) followed by carbodiimide chemistry. Cyclic voltammetry (CV) was applied during the microelectrode functionalization process to characterize the gold microelectrode surface properties. EIS analysis was made for studying the human plasma effect and for cytokine detection. The biosensor was highly selective and sensitive toward the corresponding cytokines IL-10. These were detected in real human plasma samples diluted 1000-fold, by using EIS: before LVAD implantation, after 24 hrs, and after 72 hrs of LVADs implantation at 16.9 ± 1.5 pg/mL, 62.4 ± 2.6 pg/ mL, and 37.6 ± 6.2 pg/mL, respectively. IL-10 was also detected by enzyme-linked immunosorbent assay (ELISA) using the same plasma samples for the same periods of LVAD implantation at 11.3 pg/mL, 57.2 pg/mL, and 34.0 pg/mL, respectively. The present electrochemical biosensor is very promising for an alternative, rapid, low cost, and sensitive technique for cytokine detection that could be at the patient’s bedside using point-of-care testing (POCT). This can provide rapid quantitative information to clinicians and doctors in order to predict the first signs of inflammation after LVAD implantation.

A Highly Sensitive Miniaturized Impedimetric Perchlorate Chemical Sensor

In this paper, we have developed a miniaturized a chemical sensor based on a new nanostructured Co-phthalocyanine (Co(II)Pc-PAA) derivative functionalized Au microelectrodes for perchlorate ClO−4 detection. The morphological properties of the sensitive layer have been characterized by contact angle measurement. The response of the obtained sensor-based CoPc/Au microelectrodes has been investigated by electrochemical impedance spectroscopy measurements. The experimental impedance data of the sensor device were analyzed by an equivalent electrical circuit using a modified Randles model for better understanding the phenomena present at the sensing membrane/electrolyte interface. Therefore, under optimized working conditions in terms of polarization and frequency, best performances have been achieved when compared with those obtained in the literature for Au electrodes-based devices functionalized with the same molecule. The present chemical sensor has provided a lower detection limit (17.3 pM), the lowest achieved until now to our knowledge, with a larger linear range from 1.73 10−11 to 10−1 M. The selectivity of the sensor has been also studied by evaluating the response towards ClO−4 with other interfering anions. The measurement were stable after ten days of the chemical sensor storage at room temperature. This is very promising for environmental application using rapid analyses and low-cost chemical sensors. Perspectives for a potentiometric sensor at higher concentrations were also assessed.

Development and application of a novel electrochemical immunosensor for tetracycline screening in honey using a fully integrated electrochemical Bio-MEMS

Tetracycline (TC) is a veterinary drug, wildly prescribed for prophylactic and therapeutic purposes. Consequently, its remaining residues in food products have to be regularized. We report in this paper about the development of a novel immunosensor based on an integrated bio micro-electromechanical system (Bio-MEMS) containing eight gold microelectrodes (µWEs), an integrated silver and platinum reference and counter electrodes, respectively. TC immobilization on the µWEs surface was conducted using three methods. The first through functionalization with 4-aminophenylacetic acid (CMA), the second by functionalization with CMA followed by preconcentration of a new structure of magnetic nanoparticles (MNPs) coated with poly (pyrrole-co-pyrrole-2-carboxylic acid) (Py/Py-COOH/MNPs) cross-linked with Ab-TC, and the last one directly through the functionalization with Py/Py-COOH/MNPs. The analyte was quantified by competitive detection with TC immobilized on the µWEs surface toward specific polyclonal antibody (Ab-TC), using a mixture of a fixed concentration of Ab-TC and decreasing levels of TC one from 0.1 pg mL-1 to 1000 pg mL-1. Microcontact printing, followed by fluorescence microscopy characterization were performed during the functionalization of the immunosensor surface to certify that the corresponding immune detection process is taking place. This immunosensor was found to be highly sensitive with a limit of detection of 1.2 pg mL-1 and specific in the presence of interferents. The standard addition method was exploited to detect TC in honey samples. The present immunosensor platform is up-and-coming for TC detection which can dramatically decrease the time of analysis providing a new pathway for advanced immunoassays development in industrial food control.

Development of biosensors for non-invasive measurements of heart failure biomarkers in saliva

Biomedical engineering research today is focused on non-invasive techniques for detection of biomarkers related to specific health issues 1. Three metal layer microelectrode (μE) sensors have been implemented to detect specific biomarkers which can be found in human saliva related with heart failure problems 2 such as interleukin and Tumore Necrosis Factor-α (TNF-α), and used as highly sensitive saliva sensors. We designed specialized μEs combining different technologies for multiple measurements aiming to a lab-on-a-chip future integration. Measurements are based to basic principles of Cyclic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS). Thus, certain planar technology was used involving three metal layers of gold, platinum and silver deposited over an oxidized silicon substrate following standard cleanroom procedures of lithography for the definition of μEs, sputtering physical vapor deposition (PVD) for gold, evaporation PVD for silver and platinum, and plasma enhanced chemical vapor deposition (PECVD) for passivation layer of silicon nitride.