Poly(acrylic acid) with disulfide bond for the elaboration of pH-responsive brush surfaces

in European Polymer Journal (2010), 46(2), 195-201

We report on a new route for the facile prepn. of pH-responsive tethered brushes on metallic surfaces, starting from poly(acrylic acid) (PAA) contg. a disulfide (S-S) bond (PAA-S-S-PAA). First, atom ... [more ▼]

We report on a new route for the facile prepn. of pH-responsive tethered brushes on metallic surfaces, starting from poly(acrylic acid) (PAA) contg. a disulfide (S-S) bond (PAA-S-S-PAA). First, atom transfer radical polymn. (ATRP) of 1-ethoxyethyl acrylate (EEA) with a disulfide-contg. initiator was performed to obtain the poly(EEA) precursor polymer (PEEA-S-S-PEEA). Deprotection of PEEA by a heating step resulted in the desired PAA chains without any further purifn. The brushes, obtained by the grafting to' of PAA-S-S-PAA onto gold, were then characterized by at. force microscopy in water at various pH values. The results evidence a large collapsing/swelling capacity. [less ▲]

Atomic force microscopy investigation of the morphology and the biological activity of protein-modified surfaces for bio- and immunosensors

in Analytical Chemistry (2007), 79(17), 6488-6495

With the purpose of developing biosensors, the reliable proof of the biological activity of two new sensor systems was obtained by atomic force microscopy (AFM) in both the imaging and the single-molecule ... [more ▼]

With the purpose of developing biosensors, the reliable proof of the biological activity of two new sensor systems was obtained by atomic force microscopy (AFM) in both the imaging and the single-molecule force spectroscopy modes. Antigens or antibodies of pharmacological interest were grafted onto self-assembled monolayers of thiols on gold, and AFM imaging demonstrated that the grafting process produced homogeneous submonolayers of isolated proteins. The analysis of the morphology of the surfaces at the different functionalization steps allowed evaluating the protein grafting density and showed that the recognition of complementary species present in the surrounding solution occurred. Single-molecule force spectroscopy experiments between the sensing surfaces and AFM probes, onto which the complementary species were grafted, enabled a direct and rapid test of the biological activity of the sensors by investigating the interaction occurring at the level of one single ligand-receptor bond. Ellipsometry and surface plasmon resonance allowed further characterization of the sensor surfaces and confirmed that the biological recognition took place. [less ▲]

Surface Initiated Polymerization of Styrene from Carboxylic Acid Functionalized Polypyrrole Coated Electrode

in Langmuir (2003), 19

Surface initiated radical polymerization (SIRP) is an elegant and efficient method to produce polymer chains attached to surfaces with a high graft density. Growth of polymer chains from a gold surface ... [more ▼]

Surface initiated radical polymerization (SIRP) is an elegant and efficient method to produce polymer chains attached to surfaces with a high graft density. Growth of polymer chains from a gold surface requires the formation of a self-assembled monolayer (SAM) of thiols functionalized by reactive groups (alcohol or carboxylic acid) in order to covalently bind free radical initiator species. However, thiol desorption induced by the temperature imposed for polymerization impedes the growth of polymer chains.Wepropose therefore to coat a gold electrode with a polypyrrole (PPy) derivative containing carboxylic acid pendant groups. The resulting conducting polymer layer was shown to be strongly attached to the surface. Grafting of the initiator (azo compound) and SIRP of styrene were successfully performed on this organic layer, as demonstrated by X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (TOF SIMS), and contact angle measurements. The roughness, the morphology, and the surface uniformity of the films were investigated by atomic force microscopy (AFM). Finally, cyclic voltammetry experiments were carried out to study the influence of the polystyrene layer on the electrochemical behavior of the conducting polymer [less ▲]

Surface Modification of Polycarbonate and Poly(ethyleneterephthalate) Films and Membranes by Polyelectrolyte Deposition

in Langmuir (2001), 17

The surface modification by chemical or physical adsorption of a polyelectrolyte (polyallylamine, PAH) was established using hydrolyzed polycarbonate (PC) and poly(ethylene terephthalate) (PET) thick and ... [more ▼]

The surface modification by chemical or physical adsorption of a polyelectrolyte (polyallylamine, PAH) was established using hydrolyzed polycarbonate (PC) and poly(ethylene terephthalate) (PET) thick and thin films. Contact angle data indicated changes in the hydrophilicity of PET film surfaces in terms of the chemical treatment. XPS analysis showed that the immobilization of PAH on PET and PC films was effective and that the amount of chemically or/and physically bounded PAH depends on the pH of the electrolyte solution used for the adsorption. Similar treatments have been successfully applied to polymeric track-etched membranes. These modified membranes have been used as templates for the synthesis of polypyrrole (PPy) nanotubules. FE-SEM analysis showed that much thicker PPy tubules were obtained in modified membranes than in virgin ones. This indicates that the surface chemistry of the pore walls plays an important role in the morphology of the nanostructures synthesized within the pores [less ▲]

Electrochemically synthesized polypyrrole nanotubules : effects of different experimental conditions

in European Polymer Journal (1998), 34(12), 1767-1774

Nanotubules of polypyrrole (PPy) were electrochemically synthesized using the pores of nanoporous polycarbonate (PC) particle track-etched membranes (PTM) as templates. The influence of some conditions of ... [more ▼]

Nanotubules of polypyrrole (PPy) were electrochemically synthesized using the pores of nanoporous polycarbonate (PC) particle track-etched membranes (PTM) as templates. The influence of some conditions of electrosynthesis (electrochemical method, monomer concentration, electrolyte concentration and nature) on the kinetics of pyrrole electropolymerization and on the morphology of the obtained nanomaterials has been investigated. In particular, the empirical kinetics of the electrochemical generation of polypyrrole-perchlorate (PPy-ClO4) from aqueous solution, at 0.8 V (vs SCE) was followed by electrical charges measurement. The orders with respect to pyrrole and LiClO4 are 0.34 and 0.70 respectively. The electrogeneration of polypyrrole-polystyrenesulfonate (PPy-PSS) was also followed and shows that an increase of the electrolyte concentration increases the polymerization rate at constant potential. Finally, the morphology of PPy nanotubules doped with LiClO4 and NaPSS has been studied by high resolution emission SEM and by TEM. [less ▲]