Metal-Based Chemosensors for Important Bioanalytes

This work describes different strategies for the detection of biologically relevant analytes. The main goal was to achieve sensing in water, which is a prerequisite for application to real biological samples. In several cases, we could demonstrate that our systems were also working in blood serum, a notoriously complex medium containing proteins, sugars and salts, which can potentially interfere with our sensors. Our first analyte of choice was the lithium cation. Owing to its therapeutic uses in the field of psychology, it represents an appealing target, and an efficient chemosensor for lithium ions may find numerous uses in biomedical investigations. The first strategy that will be presented involves the use of organometallic macrocycles carrying fluorescent reporting units. These compounds were found to be potent ionophores and display a very high selectivity for lithium ions. Upon careful choice of constituent building blocks, a chemosensor displaying good affinity, selectivity, and solubility was obtained. The sensor allowed the detection of lithium ions in water and in human serum by simple fluorescence measurements (Chapter 2). Other approaches for the detection of lithium ions will be presented in Chapter 3. Instead of covalently attaching fluorescent dyes to the lithium binding unit, fluorophores that can bind in a non-covalent fashion were employed. Assays based on easily available constituents were devised. They allowed the sensing of lithium ions in the sub-millimolar concentration range. In Chapter 4, the pattern-based sensing of micromolar concentrations of small peptides in water will be described. Small peptides are ubiquitous in biology, and they are involved in many essential processes such as neurotransmission, blood pressure regulation or oxidative stress mitigation. It will be demonstrated that their selective detection can be accomplished by arrays of differential sensors: instead of building a selective sensor for a given analyte, a series of cross-reactive, unsophisticated sensors could be employed. Their differential response (fingerprint) for various analytes was interpreted via statistical methods. As a result, low micromolar concentrations of many short peptides (as well as mixtures thereof) could be measured in water and in human serum samples. In the last part (Chapter 5), the sensing properties of a sensor array will be compared with those of a dynamic combinatorial library (DCL). The DCL contains the same elements as the sensor array, but they are mixed in one pot. It is shown that the DCL can outperform the sensor array in many situations, but that an excessive complexity can be detrimental to its resolution

Towards simple control for complex, autonomous robotic applications: Combining discrete and rhythmic motor primitives

Vertebrates are able to quickly adapt to new environments in a very robust, seemingly effortless way. To explain both this adaptivity and robustness, a very promising perspective in neurosciences is the modular approach to movement generation: Movements results from combinations of a finite set of stable motor primitives organized at the spinal level. In this article we apply this concept of modular generation of movements to the control of robots with a high number of degrees of freedom, an issue that is challenging notably because planning complex, multidimensional trajectories in time-varying environments is a laborious and costly process.We thus propose to decrease the complexity of the planning phase through the use of a combination of discrete and rhythmic motor primitives, leading to the decoupling of the planning phase (i.e. the choice of behavior) and the actual trajectory generation. Such implementation eases the control of, and the switch between, different behaviors by reducing the dimensionality of the high-level commands.Moreover, since the motor primitives are generated by dynamical systems, the trajectories can be smoothly modulated, either by high-level commands to change the current behavior or by sensory feedback information to adapt to environmental constraints. In order to show the generality of our approach, we apply the framework to interactive drumming and infant crawling in a humanoid robot. These experiments illustrate the simplicity of the control architecture in terms of planning, the integration of different types of feedback (vision and contact) and the capacity of autonomously switching between different behaviors (crawling and simple reaching)

Integration of vision and central pattern generator based locomotion for path planning of a non-holonomic crawling humanoid robot

In this paper we present our work on integrating a locomotion controller based on central pattern generator (CPG) and a motion planning algorithm using artificial potential fields for a non-holonomic crawling humanoid robot, the iCub. We also integrated a vision tracker and an inverse kinematics solver to perform reaching tasks. We study the influence of the various parameters of the potential field equations on the performance of the system and prove the efficiency of our framework by testing it on a physics-based robotics simulator and partially on the real iCub

Polymer of intrinsic microporosity (PIM-7) coating affects triphasic palladium electrocatalysis

A film of the polymer of intrinsic microporosity PIM-7 is coated onto a glassy carbon electrode and the resulting effects on electron transfer reactions are studied for three different types of processes: (i) aqueous solution based, (ii) solid state surface immobilised, and (iii) electrocatalytic processes on electrodeposited palladium. The effects on reactivity for hydroquinone oxidation in aqueous phosphate buffer are shown to be linked to microporosity causing a slightly lower rate of mass transport without detrimental effects on electron transfer and reaction kinetics. Next, water-insoluble microcrystalline anthraquinone is immobilised directly into the PIM-7 film and shown to give a chemically reversible reduction process, which is enhanced in the presence of PIM-7, when compared to the case of anthraquinone immobilised directly onto bare glassy carbon. Electrodeposition of a film of nano-palladium is demonstrated to give catalytically active electrodes for the reduction/oxidation of protons/hydrogen, the reduction of oxygen, and for the oxidation of formic acid and methanol. With the PIM-7 film applied onto palladium, a mechanical stabilisation effect occurs. In addition, both the hydrogen insertion and the hydrogen evolution reactions as well as formic acid oxidation are enhanced. Effects are discussed in terms of PIM-7 beneficially affecting the interfacial reaction under triphasic conditions. The microporous polymer acts as an interfacial “gas management” layer

Polymer of Intrinsic Microporosity (PIM-7) Coating Affects Triphasic Palladium Electrocatalysis

A film of the polymer of intrinsic microporosity PIM-7 is coated onto a glassy carbon electrode and the resulting effects on electron transfer reactions are studied for three different types of processes: (i) aqueous solution based, (ii) solid state surface immobilised, and (iii) electrocatalytic processes on electrodeposited palladium. The effects on reactivity for hydroquinone oxidation in aqueous phosphate buffer are shown to be linked to microporosity causing a slightly lower rate of mass transport without detrimental effects on electron transfer and reaction kinetics. Next, water-insoluble microcrystalline anthraquinone is immobilised directly into the PIM-7 film and shown to give a chemically reversible reduction process, which is enhanced in the presence of PIM-7, when compared to the case of anthraquinone immobilised directly onto bare glassy carbon. Electrodeposition of a film of nano-palladium is demonstrated to give catalytically active electrodes for the reduction/oxidation of protons/hydrogen, the reduction of oxygen, and for the oxidation of formic acid and methanol. With the PIM-7 film applied onto palladium, a mechanical stabilisation effect occurs. In addition, both the hydrogen insertion and the hydrogen evolution reactions as well as formic acid oxidation are enhanced. Effects are discussed in terms of PIM-7 beneficially affecting the interfacial reaction under triphasic conditions. The microporous polymer acts as an interfacial “gas management” layer.</p

Pattern-Based Sensing with Metal−Dye Complexes: Sensor Arrays versus Dynamic Combinatorial Libraries

The dyes Methyl Calcein Blue, Arsenazo I, and Xylenol Orange, and the metal salts CuCl2 and NiCl2 were used to generate colorimetric sensors for peptides. Two different approaches were followed: (1) Sensors based on dynamic combinatorial libraries of metal−dye complexes were created by mixing dyes with metal salts in one pot. The optical response of these libraries was analyzed by measuring the spectral changes of the mixtures upon addition of the peptide analytes at six selected wavelengths. (2) Sensor arrays were created from six different metal−dye combinations. The six individual sensors were analyzed at one wavelength, and the resulting data was used as the input for a multivariate analysis. Both types of sensors were evaluated for their ability to differentiate 13 different di- and tripeptides. The sensors based on dynamic combinatorial libraries gave in most cases better results than the sensor array. Furthermore it was found that libraries of intermediate complexity perform best as sensors

Identification et caractérisation de gènes impliqués dans la maturation de la graine d'Arabidopsis thaliana par l'étude de mutants d'insertion ADN-T

PARIS-AgroParisTech Centre Paris (751052302) / SudocSudocFranceF

A simple fluorescence assay for the detection of fluoride in water at neutral pH

A simple assay for the detection of fluoride in water by fluorescence spectroscopy was developed. The assay is based on commercially available reagents and allows sensing of fluoride in the low millimolar concentration range with high selectivity over other anions

Ruthenium-based metallacrown complexes for the selective detection of lithium ions in water and in serum by fluorescence spectroscopy

Fluorescent dihydroxypyridine ligands were prepared by attaching pyrene-, dansyl-, and methoxycoumarin-fluorophores via dimethyleneamine linkers. The reaction of these ligands with [(p-cymene)RuCl2]2 or [(C6H5CH2NMe2H)RuCl2]2Cl2 resulted in the formation of 12-metallacrown-3 complexes, which possess strong affinity for lithium ions. By a judicious choice of the fluorophore and the arene -ligand, a macrocycle was obtained that could be used in aqueous solution to selectively and quantitatively detect lithium ions by fluorescence spectroscop