Houcine Barhoumi

Urease capacitive biosensors using functionalized magnetic nanoparticles for atrazine pesticide detection in environmental samples

A new atrazine pesticide potentiometric biosensor was described using urease biomolecules immobilized onto the insulator–semiconductor electrode and different additional materials such as glutaraldehyde as a cross-linking agent, bovine serum albumin, coated nanoparticles (Fe3O4), cationic poly(allylamine hydrochloride) and anionic poly(sodium 4-styrenesulfonate) polyelectrolytes. The effect of atrazine molecules on the activity of free and immobilized urease was studied using the ion selective electrodes (ISEs) and capacity–potential measurements C(V). The sensitivity of the modified bioelectrode to urea addition was evaluated by the capacitance method via the relationship between the evolution of the flat band potential ΔVFB and the urea concentration for values ranging from 23 to 0.04 mM. The detection of atrazine in solution was performed via its inhibiting action on the urease biosensor. An incubation time of 30 min was chosen to study the inhibition effect of atrazine for different concentrations on the urease biosensor. Under optimal experimental conditions, the enzymatic activity, the inhibition process and the analytical characteristics of the resulting ENFEC (Enzyme Field effect capacitive) system were investigated. As a result, the detection limit of atrazine via the inhibition of urease activity was about 0.13 μM with a dynamic concentration range from 10−2 to 10−7 M.

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.

Characterization of Urea Biosensor Based on the Immobilization of Bacteria Proteus Mirabilis in Interaction with Iron Oxide Nanoparticles on Gold Electrode

In this work we describe a new urea biosensor, based on the immobilization of bacteria, Proteus mirabilis on gold electrode. To improve the stability of the bio-system, additional materials were used such as functionalized Fe3O4 nanoparticles (NPs), cationic (PAH), anionic (PSS) polyelectrolytes, Bovine Serum Albumin (BSA) and glutaraldehyde as a cross-linking agent. The electrochemical performances of the developed bacteria biosensor was evaluated using the electrochemical impedance spectroscopy (EIS) and cyclic voltammetry measurements. The adhesion of the bacteria cell on gold electrode was evaluated using contact angle measurements. The morphology of bacteria and its interaction with Fe3O4 nanoparticles were evaluated with the atomic force microscopy (AFM). As a result, a sensitive, stable and reproducible urea biosensor was developed.

Characterization and Classification of Different Tunisian Geographical Olive Oils using Voltammetric Electronic Tongue

In this work, we describe a sensor based on glassy carbon electrode, employed to discriminate between olive oils from different Tunisian regions. The characterization was made using three electrochemical techniques, cyclic voltammetry (CV), differential pulse voltammetry (DPV) and square wave voltammetry (SWV). Each type of oil provides a diversity of characteristic signals that can be used as an input variable of different statistics analysis, like principle component analysis (PCA), cluster analysis (CA) and discriminate factorial analysis (DFA).The results resulting from the electrochemical methods are compared. The obtained results show the reliability of the used methods on the discrimination between olive oil qualities obtained from different regions of Tunisia.

Modified insulator semiconductor electrode with functionalized nanoparticles for Proteus mirabilis bacteria biosensor development

The development of enzymatic sensors for biological purposes such as biomedicine, pharmacy, food industry, and environmental toxicity requires the purification step of the enzyme. To prevent the loss of the enzyme activity, a new strategy is held in order to immobilize the bacteria. It will constitute the biological sensing element leading to a high operational stability and multiple adaptations to various conditions such as temperature, pH and ionic strength changes. In this work we describe the development of a urea biosensor by immobilizing Proteus mirabilis bacteria onto an insulator-semiconductor electrode on functionalized Fe3O4 nanoparticles (NPs), using cationic, Poly (allylamine hydrochloride) then anionic, Poly (sodium 4-styrenesulfonate) polyelectrolytes, BSA (serum bovin albumin), and glutaraldehyde as a cross-linking agent. The response of P. mirabilis to urea addition is evaluated in homogeneous and heterogeneous phases. Before the immobilization step, the activity of urease produced from the P. mirabilis bacteria was attempted using the ion ammonium selective electrodes (ISEs). Adhesion of the bacteria cells on IS electrodes have been studied using contact angle measurements. After immobilization of the bacteria, on the (Si/SiO2/Si3N4) and (Si/SiO2) substrates, the relationship between the evolution of the flat band potential ∆VFB and the urea concentration is found to be linear for values ranging from 10(-2)M to 10(-5)M.

Electrochemical study of a glassy carbon electrode modified by poly-4-nitroaniline-reduced/murexide and its sensitivity for metal ions

The electrochemical modification of a glassy carbon electrode using reduced poly-4 nitroaniline (P-4NA) and its applicability for determination of metallic ions was performed in this study. The electrode modification was performed by cyclic voltammetry in the potential range between 0.9 V and 1.4 V vs Ag/Ag+ (in 10 mM AgNO3) at the scan rate of 100 mV/s by 50 cycles in non-aqueous media. The reduction of nitro groups on the P-4NA modified glassy carbon electrode surface was performed in the potential range between -0.1 V and -0.8 V vs Ag/AgCl(Sat. KCl) at a scan rate of 100 mV/s in 100 mM aqueous HCl solution. The reduced P-4NA glassy carbon surface was modified with the murexide. The affinity of the modified glassy carbon electrode with some metallic ions was investigated by electrochemical impedance spectroscopy method in phosphate buffer solution (pH = 5).

New modified selective platinum electrode based on poly (ethylene glycol) for Iron (III) detection in real water

Purpose This work aims to determine iron (III) in real water by using a new amperometric sensor on the basis of polyethylene glycol (PEG) to test and characterize a new modified selective platinum electrode. Design/methodology/approach In this review, the authors focus on testing and characterizing several polymeric membranes by using cyclic voltammetry and square-wave voltammetry (SWV) methods to differentiate the nature of plasticizers (2-Nitrophenyl octyl ether [NPOE], Di-n-octyl phthalate, Bis (2-ethylhexyl) sebacate, PEG. The authors have evaluated the possibility of using crown ether and three zeolite ionophore (faujasite [FAU], Chabazite and ZSM-5) matrixes as novel materials for the selective determination of iron (III) using SWV for the best membranes. Findings The results demonstrated that the modified platinum electrode presents linear dependence of amperometric signal with a wide linear range of 10−9 to 10−4 mol.L−1 for iron determination, revealing a detection limit of 10−10 mol.L−1 and amperometric sensibility of 58.58 µA/mol.L−1. The slope of the membrane plasticized with PEG calibration curve is six times higher than that of the other membranes. It was noticed that when the crown ether and the three zeolite ionophores were used, as a new detective material for iron with the membrane plasticized with PEG, the expected results were highly proven. The modified platinum electrode showed high selectivity to iron (III) when the heavy metal ions such as Ni (II), Al (III), Zn (III), Cd (II), Gd (II) and Cu (II) were present. Originality/value The utility of the method and the efficiency of the best membrane sensor have been accurately tested by the determination of iron in real water samples of Hassi Messaoud, south of Algeria.