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Laboratoire d’Excellence SEAM « Science and Engineering for Advanced Materials and devices »

Article mis en ligne le 11 décembre 2017
dernière modification le 10 janvier 2018
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A3 : Functionalization & nano-structuration of surfaces


Research on the functionalization and nanostructuration of various surfaces has been speeding up these past five years for the development of new sensors and biosensors and original molecular electronic devices. These domains are currently under study at ITODYS, together with LSPM, MSC, MPQ and LPL.

Sensors and biosensors

CNTs based hybrids, ie. CNTS coupled to organometallic groups such as metallophthalocyanines, exhibit electrocatalytic activity toward several electrochemical reactions and anchored to a surface will be studied to developed new and efficient electrodes. Electrochemically prepared polymers mixed or not to metal nanoparticules or metallic complexes graffed on a surface may form also very sensitive electrodes. DNA-based biosensors with direct electrochemical detection have been already developped. The original results based on analyzing the interactions between gene and electroactive probes allows extending this approach to promising biomimetic molecules such as peptido-nucleic acids (PNA), sequence of DNA (aptamers) to detect chiral molecules and also oligopeptides for detecting proteins, antibodies biochemical markers.

Different strategies for functionalizing electrode surfaces by ultrathin organic layers will be based on electroformed conductive polymers, electrografted aryl groups or oligomers derived from diazonium salts which are nonmanual methods that allow miniaturisation and functionalization over a large scale, from several square centimetres down to nanodomains. Molecular imprinted polymers (MIPs) with specific recognition nanocavities may act as artificial antibodies and exhibit high selectivity toward the imprinted molecules (organic compounds, bioorganic molecules, metal ions). New methodologies for enhancing mass-transfer through the elaboration of thin films covalently grafted onto an electrode or 3D hierarchical macroporous structures and sensitivity by coupling MIP elements to voltammetric tranducers or to photonic crystals will be developed with the goal to design nanometer-sized hybrid inorganic nanosupport/MIP systems. Diamond is also a material of choice for sensors. Boron doped diamond as well as hydrogenated diamond surface modifiy the electrical conductivity of diamond making it suitable for conception of new sensing devices. Functionalization of diamond layers by photochemically or sonochemically assisted grafting of phenyldiazonium or double functionalized silanes for further immobilisation of biomolecules (enzymes, for example), and control of the diamond/metal interface for implementing ohmic contacts will be an important focus.

These approaches will be investigated in collaboration between ITODYS, LSPM, LPL, MSC and MPQ. Molecular electronics Molecular transport at the nanometer scale has shed new light on many body phenomena in condensed matter (molecular domains at 2D (monolayers), 2D (monolayers), 1D (wire), or 0D (dots)). This approach at various dimensions allows the full understanding of the effect of reduction of size on molecular transport. This needs a tight collaboration between physicists of electronic transport under tip (STM at MPQ) or not (TELEM team at MPQ) and chemists (ITODYS) specialists of electroactive/materials tailored for their grafting and self-assembling capacities onto surfaces. We will fabricate junctions between one molecule and two metallic contacts and investigate how the experimental signatures of quantum transport are modified when a single molecule is inserted in a nanogap. We will also elaborate nano-structured networks using templates, self assembling, nanoprinting, and by formation of mesoporous 2D networks from solutions, the filling of the pores being then carried out by electrochemistry, dipping, or vacuum evaporation. Transport measurements adapted to such nanostructures are necessary. Direct transport measurements through single molecules can be performed at very low temperature and under magnetic field either in transistor geometry with nanometer-spaced electrodes fabricated by controlled electromigration of nanowires or by STM (MPQ - ITODYS). Specific phenomena occurring at the nanometre scale level like the Kondo effect in presence of ferromagnetism or the magneto-Coulomb blockade will be studied. The interaction between between Physicists and Chemists is of particular importance in this field.

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