Ali Othmane - Profile on Academia.edu (original) (raw)

Papers by Ali Othmane

Optimized biosensing interface of bacteria-based microsensor for heavy metals detection

Elaboration et étude impédimétrique des électrodes d'or fonctionnalisées par des cyclames mono-N-fonctionnalisés

ABSTRACT communication par affiche

Legionella pneumophila detection by Electrochemical Impedance Spectroscopy (présentation orale)

Journal of Communications Engineering and Networks, 2014

Engineering the surface chemistry of a material so that it can interface with cells is an extraor... more Engineering the surface chemistry of a material so that it can interface with cells is an extraordinarily demanding task. The surface of a cell is composed of thousands of different lipids, proteins and carbohydrates, all intricately (and dynamically) arranged in three dimensions on multiple length scales. This complexity presents both a challenge and an opportunity to chemists working on bioactive interfaces.

Développement et évaluation d’un micro-biocapteur pour l’immunodétection en temps réel de Legionella pneumophila dans les prélèvements environnementaux

The seeding of endothelial cells on biomaterial surfaces has become a major challenge to achieve ... more The seeding of endothelial cells on biomaterial surfaces has become a major challenge to achieve better haemocompatibility of these surfaces. Multilayers of polyelectrolytes formed by the layerby-layer method are promising in this respect. In this study, the interactions of endothelial cells with multilayered polyelectrolytes films were investigated. The build-ups were prepared by selfassembled alternatively adsorbed polyanions and polycations functionalised with fibronectin and collagen. Anionic poly(sodium 4-styrenesulfonate) and cationic poly(allylamine hydrochloride) polyelectrolytes were chosen as a model system. Elaborated surfaces were characterised by electrochemical impedance spectroscopy and cyclic voltammetry. The modified electrode showed good reversible electrochemical properties and high stability in an electrolyte solution. The film ohmic resistance was highest when the film was coated with fibronectin; the parameters so determined were correlated with atomic force microscopy images. Cell colorimetric assay (WST-1) and immunofluorescence were used to quantify the cell viability and evaluate the adhesion properties. When cultured on a surface where proteins were deposited, cells adhered and proliferated better with fibronectin than with collagen. In addition, a high surface free energy was favourable to adhesion and proliferation (48.8 mJ m −2 for fibronectin and 39.7 mJ m −2 for collagen, respectively). Endothelial cells seeded on functionalised-polyelectrolyte multilayer films showed a good morphology and adhesion necessary for the development of a new endothelium.

Optimization of physicochemical parameters of a multilayered polyelectrolyte film deposition with Love wave and AFM for bacteria based detection of heavy metal

A biosensor based on Escherichia coli Bacteria for determination of heavy metal ions with an acou... more A biosensor based on Escherichia coli Bacteria for determination of heavy metal ions with an acoustic Love wave device and Polydimethylsiloxane (PDMS) microfluidic network has been previously developed, that provides fast detection of toxic chemical compounds. Bacteria were immobilized on the transducer coated with self-assembled molecular multilayers of polyelectrolytes. In this study, we emphasize Love wave and AFM-based complementary characterization methods, which allowed an optimization of some physicochemical parameters of polyelectrolyte solutions, such as pH, ionic strength or molecular weight, in order to increase the immobilization of bacteria as well as the sensor lifetime. For instance, an increase density of bacteria was observed when using alternative pH of 9 for cationic solution.

Love wave bacterial biosensors for the detection of heavy metal toxicity in liquid medium

Talanta, Jan 15, 2011

Specific recognition between two biological partners is widely exploited in biosensors nowadays. ... more Specific recognition between two biological partners is widely exploited in biosensors nowadays. To explore this avenue, a novel biosensor for antithrombin (AT) detection was constructed. Heparin was used as the affinity ligand. A well-known acrylic monomer (butyl methacrylate) was polymerized and grafted onto the heparin polysaccharide by the use of ceric ammonium nitrate as a redox initiator in aqueous nitric acid medium. Polymers were deposited as a thin layer onto surface of stainless steel electrode (SS316L). The obtained polymers were studied by Fourier transform infrared spectroscopy (FTIR) and analyzed by differential scanning calorimetry (DSC). Moreover, the films were characterized by electrochemical impedance spectroscopy (EIS), contact-angle measurements and AFM. EIS was used to study the biosensor affinity to AT and the relationship between functionalization growth of modified electrode and the response of the sensor. The proposed approach appears to be simple, sensitiv...

A Hybrid System Based on an Electronic Nose Coupled with an Electronic Tongue for the Characterization of Moroccan Waters

Abstract: A hybrid multisensor system combined with multivariate analysis was applied to the char... more Abstract: A hybrid multisensor system combined with multivariate analysis was applied to the characterization of different kinds of Moroccan waters. The proposed hybrid system based on an electronic nose coupled with an electronic tongue consisted of metal oxide semiconductors and potentiometric sensors respectively. Five Taguchi Gas Sensors were implemented in the electronic nose for the discrimination between mineral, natural, sparkling, river and tap waters. Afterwards, the electronic tongue, based on series of Ion-Selective-Electrodes was applied to the analysis of the same waters. Multisensor responses obtained from the waters were processed by two chemometrics: Principal Component Analysis (PCA) and Linear Discriminant Analysis (LDA). PCA results using electronic nose data depict all of the potable water samples in a separate group from the samples that were originated from river. Furthermore, PCA and LDA analysis on electronic tongue data permitted clear and rapid recognizing...

Instrumentation Mesure Métrologie, 2013

RESUME. Le potentiel offert par les capteurs piézoélectriques SH-SAW pour des détections en milie... more RESUME. Le potentiel offert par les capteurs piézoélectriques SH-SAW pour des détections en milieux biologiques est clairement démontré à travers deux applications particulières. La première concerne la mise en évidence d'un appariement entre un oligonucléotide et un analogue de tétranucléotide présentant un lien triazolique. Cette affinité, mise en évidence pour la première fois, permet d'envisager l'utilisation de ces analogues synthétiques en tant qu'agents thérapeutiques. La seconde est dédiée à la détection d'une mutation ponctuelle (SBM) au niveau d'un gène codant pour l'Apolipoprotéine E (ApoE). Outre la possibilité de discriminer une complémentarité totale ou partielle d'une non complémentarité, les biocapteurs SH-SAW ont également montré qu'ils étaient sensibles aussi bien à la nature qu'à la position d'une mutation dans une séquence ADN considérée.

Sensors and Actuators B: Chemical, 2014

The synthesis and properties of new silicone-based functional materials having attached cyclam ma... more The synthesis and properties of new silicone-based functional materials having attached cyclam macrocycles have been assessed with regard to their application as ion-sensitive membranes of chemical sensors. The preparation process of thin films of the sensitive materials has been designed so that each chemical compound is attached by means of chemical bonds: the macrocyclic ionophore was chemically bound to the silicone polymer and the polymer material was attached to the sensitive surface of the electrochemical devices by means of chemical grafting. The properties of such materials have been evaluated for detection of iron(III) species in water using ion-sensitive field-effect transistor (ISFET) and electrolyte-insulator-semiconductor (EIS) structures, both sensitized by a coating with the functional polymer materials. Two types of cyclam derivatives and two types of synthesis processes have been compared with that respect. The first material, "PDMS-Cyclam", was prepared by grafting N-10undecenyl-cyclam to poly(methylhydrosiloxane) (PMHS). The cyclam ionophore of the second material, "PDMS-Naphthyl-Cyclam", bore a naphthyl pendent group that enhanced the complexing properties for Fe 3+ ions. Linear response with respect to the pFe(III) = −Log[Fe 3+ ] was observed over three decades (EIS) or two decades (ISFET) of concentration. A Nernstian response toward Fe 3+ ions was observed for the "PDMS-Naphthyl-Cyclam" membrane. These devices exhibit good chemical stability and a long lifetime in aqueous medium.

Macromolecular Bioscience, 2007

Aggregation and deformation of red blood cells as probed by a laser light scattering technique in a concentrated suspension: comparison between normal and pathological red blood cells

Changes in aggregability and/or deformability of red blood cells (RBC) can cause severe complicat... more Changes in aggregability and/or deformability of red blood cells (RBC) can cause severe complications in blood circulation. We use a laser light scattering technique, which can distinguish between normal and pathological RBCs by studying the angular distributions of backscattered and transmitted light of concentrated suspensions of RBCs submitted to a simple shear flow. In order to study the deformation, we induced partial rigidity in the RBC membrane, and showed that the gradients of deformation and the relaxation times of normal and partially rigidified RBC membranes can be quantified using a non-Newtonian rheological model. We observe that blood aggregation of patients with `microcirculatory' diseases, such as diabetes, differs from that of healthy individuals.

Sensors and Actuators B: Chemical, 2014

Environmental pollution by toxic heavy metals (HM) presents a real threat for aquatic medium and ... more Environmental pollution by toxic heavy metals (HM) presents a real threat for aquatic medium and human health. Therefore aquatic ecosystem management requires early warning systems for on line monitoring. Microtechnologies can give rise to innovative bio-inspired hybrid microsensors, likely to meet this need and providing cost reductions by reducing reagents consumption and manufacturing cost.

Sensors and Actuators B: Chemical, 2002

Adhesive interactions between antigen±antibody play a central role in immune system operation. Th... more Adhesive interactions between antigen±antibody play a central role in immune system operation. The objective of this paper is to detect immune complexes without any label, by using atomic force microscopy (AFM). We have proceeded by imaging antibody (anti-rabbit IgG) or anti-rabbit IgG moieties adsorbed onto mica surface, before and after incubation of two kinds of antigens: a speci®c (rabbit IgG) and a non-peci®c one (sheep IgG). The analysis using the height histograms reveals many interesting features. We propose a general framework for interpreting height histogram measurements, which enable the discrimination between speci®c and non-speci®c complexes. #

Sensor Letters, 2011

The present work deals with the development of a Love-wave bacteria-based sensor platform for the... more The present work deals with the development of a Love-wave bacteria-based sensor platform for the detection of heavy metals in liquid medium. The acoustic delay-line is inserted in an oscillation loop in order to record the resonance frequency in real-time. A Polydimethylsiloxane (PDMS) chip with a liquid chamber is maintained by pressure above the acoustic wave propagation path.

Biomolecular Engineering, 2002

The aim of this work is to detect immune complexes without any kind of labelling of each of the i... more The aim of this work is to detect immune complexes without any kind of labelling of each of the immunological species, with a view to create a very sensitive biosensor. This is achieved by using the atomic force microscopy. We have proceeded by imaging the antibody (anti-rabbit IgG) or anti-rabbit IgG moieties adsorbed onto mica surface, before and after incubation of two kinds of antigens: a specific (rabbit IgG) and a non-specific one (sheep IgG). The analysis using the height histograms reveals many interesting features. We propose a general framework for interpreting these analysis, which enables the discrimination between specific and non-specific complexes. #

Quantification of the adhesion free energy between bacteria and hydrophobic and hydrophilic substrata

Materials Science and Engineering: C, 2006

... Quantification of the adhesion free energy between bacteria and hydrophobic and hydrophilic s... more ... Quantification of the adhesion free energy between bacteria and hydrophobic and hydrophilic substrata. ... a, Laboratoire de Physique et Chimie des Interfaces, Faculté des Sciences de Monastir,Tunisia. b, Laboratoire de Biophysique, Faculté de Médecine de Monastir, Tunisia. ...

Optimized biosensing interface of bacteria-based microsensor for heavy metals detection

Elaboration et étude impédimétrique des électrodes d'or fonctionnalisées par des cyclames mono-N-fonctionnalisés

ABSTRACT communication par affiche

Legionella pneumophila detection by Electrochemical Impedance Spectroscopy (présentation orale)

Journal of Communications Engineering and Networks, 2014

Engineering the surface chemistry of a material so that it can interface with cells is an extraor... more Engineering the surface chemistry of a material so that it can interface with cells is an extraordinarily demanding task. The surface of a cell is composed of thousands of different lipids, proteins and carbohydrates, all intricately (and dynamically) arranged in three dimensions on multiple length scales. This complexity presents both a challenge and an opportunity to chemists working on bioactive interfaces.

Développement et évaluation d’un micro-biocapteur pour l’immunodétection en temps réel de Legionella pneumophila dans les prélèvements environnementaux

The seeding of endothelial cells on biomaterial surfaces has become a major challenge to achieve ... more The seeding of endothelial cells on biomaterial surfaces has become a major challenge to achieve better haemocompatibility of these surfaces. Multilayers of polyelectrolytes formed by the layerby-layer method are promising in this respect. In this study, the interactions of endothelial cells with multilayered polyelectrolytes films were investigated. The build-ups were prepared by selfassembled alternatively adsorbed polyanions and polycations functionalised with fibronectin and collagen. Anionic poly(sodium 4-styrenesulfonate) and cationic poly(allylamine hydrochloride) polyelectrolytes were chosen as a model system. Elaborated surfaces were characterised by electrochemical impedance spectroscopy and cyclic voltammetry. The modified electrode showed good reversible electrochemical properties and high stability in an electrolyte solution. The film ohmic resistance was highest when the film was coated with fibronectin; the parameters so determined were correlated with atomic force microscopy images. Cell colorimetric assay (WST-1) and immunofluorescence were used to quantify the cell viability and evaluate the adhesion properties. When cultured on a surface where proteins were deposited, cells adhered and proliferated better with fibronectin than with collagen. In addition, a high surface free energy was favourable to adhesion and proliferation (48.8 mJ m −2 for fibronectin and 39.7 mJ m −2 for collagen, respectively). Endothelial cells seeded on functionalised-polyelectrolyte multilayer films showed a good morphology and adhesion necessary for the development of a new endothelium.

Optimization of physicochemical parameters of a multilayered polyelectrolyte film deposition with Love wave and AFM for bacteria based detection of heavy metal

A biosensor based on Escherichia coli Bacteria for determination of heavy metal ions with an acou... more A biosensor based on Escherichia coli Bacteria for determination of heavy metal ions with an acoustic Love wave device and Polydimethylsiloxane (PDMS) microfluidic network has been previously developed, that provides fast detection of toxic chemical compounds. Bacteria were immobilized on the transducer coated with self-assembled molecular multilayers of polyelectrolytes. In this study, we emphasize Love wave and AFM-based complementary characterization methods, which allowed an optimization of some physicochemical parameters of polyelectrolyte solutions, such as pH, ionic strength or molecular weight, in order to increase the immobilization of bacteria as well as the sensor lifetime. For instance, an increase density of bacteria was observed when using alternative pH of 9 for cationic solution.

Love wave bacterial biosensors for the detection of heavy metal toxicity in liquid medium

Talanta, Jan 15, 2011

Specific recognition between two biological partners is widely exploited in biosensors nowadays. ... more Specific recognition between two biological partners is widely exploited in biosensors nowadays. To explore this avenue, a novel biosensor for antithrombin (AT) detection was constructed. Heparin was used as the affinity ligand. A well-known acrylic monomer (butyl methacrylate) was polymerized and grafted onto the heparin polysaccharide by the use of ceric ammonium nitrate as a redox initiator in aqueous nitric acid medium. Polymers were deposited as a thin layer onto surface of stainless steel electrode (SS316L). The obtained polymers were studied by Fourier transform infrared spectroscopy (FTIR) and analyzed by differential scanning calorimetry (DSC). Moreover, the films were characterized by electrochemical impedance spectroscopy (EIS), contact-angle measurements and AFM. EIS was used to study the biosensor affinity to AT and the relationship between functionalization growth of modified electrode and the response of the sensor. The proposed approach appears to be simple, sensitiv...

A Hybrid System Based on an Electronic Nose Coupled with an Electronic Tongue for the Characterization of Moroccan Waters

Abstract: A hybrid multisensor system combined with multivariate analysis was applied to the char... more Abstract: A hybrid multisensor system combined with multivariate analysis was applied to the characterization of different kinds of Moroccan waters. The proposed hybrid system based on an electronic nose coupled with an electronic tongue consisted of metal oxide semiconductors and potentiometric sensors respectively. Five Taguchi Gas Sensors were implemented in the electronic nose for the discrimination between mineral, natural, sparkling, river and tap waters. Afterwards, the electronic tongue, based on series of Ion-Selective-Electrodes was applied to the analysis of the same waters. Multisensor responses obtained from the waters were processed by two chemometrics: Principal Component Analysis (PCA) and Linear Discriminant Analysis (LDA). PCA results using electronic nose data depict all of the potable water samples in a separate group from the samples that were originated from river. Furthermore, PCA and LDA analysis on electronic tongue data permitted clear and rapid recognizing...

Instrumentation Mesure Métrologie, 2013

RESUME. Le potentiel offert par les capteurs piézoélectriques SH-SAW pour des détections en milie... more RESUME. Le potentiel offert par les capteurs piézoélectriques SH-SAW pour des détections en milieux biologiques est clairement démontré à travers deux applications particulières. La première concerne la mise en évidence d'un appariement entre un oligonucléotide et un analogue de tétranucléotide présentant un lien triazolique. Cette affinité, mise en évidence pour la première fois, permet d'envisager l'utilisation de ces analogues synthétiques en tant qu'agents thérapeutiques. La seconde est dédiée à la détection d'une mutation ponctuelle (SBM) au niveau d'un gène codant pour l'Apolipoprotéine E (ApoE). Outre la possibilité de discriminer une complémentarité totale ou partielle d'une non complémentarité, les biocapteurs SH-SAW ont également montré qu'ils étaient sensibles aussi bien à la nature qu'à la position d'une mutation dans une séquence ADN considérée.

Sensors and Actuators B: Chemical, 2014

The synthesis and properties of new silicone-based functional materials having attached cyclam ma... more The synthesis and properties of new silicone-based functional materials having attached cyclam macrocycles have been assessed with regard to their application as ion-sensitive membranes of chemical sensors. The preparation process of thin films of the sensitive materials has been designed so that each chemical compound is attached by means of chemical bonds: the macrocyclic ionophore was chemically bound to the silicone polymer and the polymer material was attached to the sensitive surface of the electrochemical devices by means of chemical grafting. The properties of such materials have been evaluated for detection of iron(III) species in water using ion-sensitive field-effect transistor (ISFET) and electrolyte-insulator-semiconductor (EIS) structures, both sensitized by a coating with the functional polymer materials. Two types of cyclam derivatives and two types of synthesis processes have been compared with that respect. The first material, "PDMS-Cyclam", was prepared by grafting N-10undecenyl-cyclam to poly(methylhydrosiloxane) (PMHS). The cyclam ionophore of the second material, "PDMS-Naphthyl-Cyclam", bore a naphthyl pendent group that enhanced the complexing properties for Fe 3+ ions. Linear response with respect to the pFe(III) = −Log[Fe 3+ ] was observed over three decades (EIS) or two decades (ISFET) of concentration. A Nernstian response toward Fe 3+ ions was observed for the "PDMS-Naphthyl-Cyclam" membrane. These devices exhibit good chemical stability and a long lifetime in aqueous medium.

Macromolecular Bioscience, 2007

Aggregation and deformation of red blood cells as probed by a laser light scattering technique in a concentrated suspension: comparison between normal and pathological red blood cells

Changes in aggregability and/or deformability of red blood cells (RBC) can cause severe complicat... more Changes in aggregability and/or deformability of red blood cells (RBC) can cause severe complications in blood circulation. We use a laser light scattering technique, which can distinguish between normal and pathological RBCs by studying the angular distributions of backscattered and transmitted light of concentrated suspensions of RBCs submitted to a simple shear flow. In order to study the deformation, we induced partial rigidity in the RBC membrane, and showed that the gradients of deformation and the relaxation times of normal and partially rigidified RBC membranes can be quantified using a non-Newtonian rheological model. We observe that blood aggregation of patients with `microcirculatory' diseases, such as diabetes, differs from that of healthy individuals.

Sensors and Actuators B: Chemical, 2014

Environmental pollution by toxic heavy metals (HM) presents a real threat for aquatic medium and ... more Environmental pollution by toxic heavy metals (HM) presents a real threat for aquatic medium and human health. Therefore aquatic ecosystem management requires early warning systems for on line monitoring. Microtechnologies can give rise to innovative bio-inspired hybrid microsensors, likely to meet this need and providing cost reductions by reducing reagents consumption and manufacturing cost.

Sensors and Actuators B: Chemical, 2002

Adhesive interactions between antigen±antibody play a central role in immune system operation. Th... more Adhesive interactions between antigen±antibody play a central role in immune system operation. The objective of this paper is to detect immune complexes without any label, by using atomic force microscopy (AFM). We have proceeded by imaging antibody (anti-rabbit IgG) or anti-rabbit IgG moieties adsorbed onto mica surface, before and after incubation of two kinds of antigens: a speci®c (rabbit IgG) and a non-peci®c one (sheep IgG). The analysis using the height histograms reveals many interesting features. We propose a general framework for interpreting height histogram measurements, which enable the discrimination between speci®c and non-speci®c complexes. #

Sensor Letters, 2011

The present work deals with the development of a Love-wave bacteria-based sensor platform for the... more The present work deals with the development of a Love-wave bacteria-based sensor platform for the detection of heavy metals in liquid medium. The acoustic delay-line is inserted in an oscillation loop in order to record the resonance frequency in real-time. A Polydimethylsiloxane (PDMS) chip with a liquid chamber is maintained by pressure above the acoustic wave propagation path.

Biomolecular Engineering, 2002

The aim of this work is to detect immune complexes without any kind of labelling of each of the i... more The aim of this work is to detect immune complexes without any kind of labelling of each of the immunological species, with a view to create a very sensitive biosensor. This is achieved by using the atomic force microscopy. We have proceeded by imaging the antibody (anti-rabbit IgG) or anti-rabbit IgG moieties adsorbed onto mica surface, before and after incubation of two kinds of antigens: a specific (rabbit IgG) and a non-specific one (sheep IgG). The analysis using the height histograms reveals many interesting features. We propose a general framework for interpreting these analysis, which enables the discrimination between specific and non-specific complexes. #

Quantification of the adhesion free energy between bacteria and hydrophobic and hydrophilic substrata

Materials Science and Engineering: C, 2006

... Quantification of the adhesion free energy between bacteria and hydrophobic and hydrophilic s... more ... Quantification of the adhesion free energy between bacteria and hydrophobic and hydrophilic substrata. ... a, Laboratoire de Physique et Chimie des Interfaces, Faculté des Sciences de Monastir,Tunisia. b, Laboratoire de Biophysique, Faculté de Médecine de Monastir, Tunisia. ...