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ABSTRACT: A new 2D molecular imprinting technique based on nanotemplating and soft-lithography techniques is reported. This technique allows the creation of target-specific synthetic recognition sites on different substrates using a uniquely oriented and immobilized template and the attachment of a molecularly imprinted polymer on a substrate. The molecularly imprinted polymer was characterized by AFM, fluorescence microscopy, and ATR-FTIR. We evaluated the rebinding ability of the sites with theophylline (the target molecule). The selectivity of the molecularly imprinted polymer was determined for the theophylline-caffeine couple. The molecularly imprinted polymer exhibited selectivity for theophylline, as revealed by competitive rebinding experiments. Fluorescence microscopy experiments provided complementary proof of the selectivity of the molecularly imprinted polymer surfaces toward theophylline. These selective molecularly imprinted polymers have the potential for chemical sensor applications. Because of its 2D nature, this novel chemical sensor technology can be integrated with many existing high-sensitivity multichannel detection technologies.
Langmuir 06/2007; 23(10):5452-8. · 4.19 Impact Factor
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ABSTRACT: Platinum-ruthenium nanoparticles stabilized within a conductive polymer matrix are prepared using microwave heating. Polypyrrole di(2-ethylhexyl) sulfosuccinate, or PPyDEHS, has been chosen for its known electrical conductivity, thermal stability, and solubility in polar organic solvents. A scalable and quick two-step process is proposed to fabricate alloyed nanoparticles dispersed in PPyDEHS. First a mixture of PPyDEHS and metallic precursors is heated in a microwave under reflux conditions. Then the nanoparticles are extracted by centrifugation. Physical characterization by TEM shows that crystalline and monodisperse alloyed nanoparticles with an average size of 2.8 nm are obtained. Diffraction data show that crystallite size is around 2.0 nm. Methanol electro-oxidation data allow us to propose these novel materials as potential candidates for direct methanol fuel cells (DMFC) application. The observed decrease in sulfur content in the polymer upon incorporation of PtRu nanoparticles may have adversely affected the measured catalytic activity by decreasing the conductivity of PPyDEHS. Higher concentration of polymer leads to lower catalyst activity. Design and synthesis of novel conductive polymers is needed at this point to enhance the catalytic properties of these hybrid materials.
The Journal of Physical Chemistry B 09/2005; 109(32):15339-44. · 3.70 Impact Factor
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ABSTRACT: The effect of immersion time on the ordering properties of self-assembled docosanethiolate (C22) monolayers has been studied by reflection/absorption infrared spectroscopy (RAIRS). Starting with a chemically cleaned polycrystalline gold surface, we have found that an immersion time of 45 s in micromolar thiol solutions is sufficient to produce ordered “monolayer” films. These films have RAIR spectral features (peak position, line width, and integrated intensity) similar to those obtained with much longer immersion times. Decreasing the immersion time below 45 s gradually increases the disorder. The temperature dependence of the CH2 antisymmetric stretching (d-) peak position of thiol films obtained with an immersion time of 120 s is identical to ones obtained with very long immersion time (0.5 h to several days). In contrast, films obtained with a 5 s immersion time disorder at a lower temperature. Apart from immersion time and temperature, a large solvent effect has been observed based on real-time RAIRS measurements of the continuing film ordering during aging in vacuum. Finally, a new assignment of the shoulder appearing around 2931 cm-1 is proposed. We present arguments suggesting that the generally accepted Fermi resonance assignment of this shoulder should be modified to include a contribution from another vibrational mode.
09/1997;
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ABSTRACT: A novel alkylthioacetyl-capped hydroxyethyl methacrylate monomer and its corresponding homopolymer have been synthesized and characterized. Direct chemisorption of these moieties have been carried out on gold-coated substrate and found to form a strong surface bonding. The surface coverage and the properties of the resultant self-assembled layers have been investigated by multiple surface characterization techniques (i.e. ellipsometry, GA-FTIR, XPS, AFM, and contact angle measurements). These analyses have all confirmed the occurrence of complete chemisorption reactions with typical n-alkanethiol self-assembled characteristics.
Applied Surface Science 252(14):5158-5167. · 2.10 Impact Factor
