Electrodes for Membrane Surface Science. Bilayer Lipid Membranes Tethered by Commercial Surfactants on Electrochemical Sensors.

Commercial surfactants, which are inexpensive and abundant, were covalently grafted to flat and transparent electrodes, and it appears to be a simple functionalization route to design biomembrane sensors at large-scale production. Sparsely tethered bilayer lipid membranes (stBLM) were stabilized using such molecular coatings composed of diluted anchor-harpoon surfactants that grab the membrane with an alkyl chain out of a PEGylated-hydrogel layer, which acts as a soft hydration cushion. The goal of avoiding the synthesis of complex organic molecules to scale up sensors was achieved here by grafting nonionic diblock oligomers (Brij58 = C H(OCHCH) OH with x = 16 and n = 23) and PEO short chains ((OCHCH) OH with n = 9 and n = 23) from their hydroxyl (-OH) end-moiety to a monolayer of -Ar-SOCl groups, which are easy to form on electrodes (metals, semiconducting materials, .

Grafting Commercial Surfactants (Brij, CiEj) and PEG to Electrodes via Aryldiazonium Salts.

Grafting commercial surfactants appears to be a simple way to modify electrodes and conducting interfaces, avoiding the synthesis of complex organic molecules. A new surface functionalization route is presented to build surfactant coatings with monolayer thickness grafting molecules considered as nonreactive. A monolayer of -SOCl functions (from a p-benzenesulfonyl chloride) was first electrografted.

Kinetic analysis of the interaction of Mos1 transposase with its inverted terminal repeats reveals new insight into the protein-DNA complex assembly.

Transposases are specific DNA-binding proteins that promote the mobility of discrete DNA segments. We used a combination of physicochemical approaches to describe the association of MOS1 (an eukaryotic transposase) with its specific target DNA, an event corresponding to the first steps of the transposition cycle. Because the kinetic constants of the reaction are still unknown, we aimed to determine them by using quartz crystal microbalance on two sources of recombinant MOS1: one produced in insect cells and the other produced in bacteria.

Assessment of DNA binding to human Rad51 protein by using quartz crystal microbalance and atomic force microscopy: effects of ADP and BRC4-28 peptide inhibitor.

The interaction of human Rad51 protein (HsRad51) with single-stranded deoxyribonucleic acid (ssDNA) was investigated by using quartz crystal microbalance (QCM) monitoring and atomic force microscopy (AFM) visualization. Gold surfaces for QCM and AFM were modified by electrografting of the in situ generated aryldiazonium salt from the sulfanilic acid to obtain the organic layer Au-ArSO3 H. The Au-ArSO3 H layer was activated by using a solution of PCl5 in CH2 Cl2 to give a Au-ArSO2 Cl layer.

Bacterial adhesion and growth reduction by novel rubber-derived oligomers.

In the medical field, attached bacteria can cause infections associated with catheters, incisions, burns, and medical implants especially in immunocompromised patients. The problem is exacerbated by the fact that attached bacteria are ∼1000 times more resistant to antibiotics than planktonic cells. The rapid spread of antibiotic resistance in these and other organisms has led to a significant need to find new methods for preventing bacterial attachment.

Antifouling action of polyisoprene-based coatings by inhibition of photosynthesis in microalgae.

Previous studies have demonstrated that ionic and non-ionic natural rubber-based coatings inhibit adhesion and growth of marine bacteria, fungi, microalgae, and spores of macroalgae. Nevertheless, the mechanism of action of these coatings on the different micro-organisms is not known. In the current study, antifouling activity of a series of these rubber-based coatings (one ionic and two non-ionic) was studied with respect to impacts on marine microalgal photosynthesis using pulse-amplitude-modulation (PAM) fluorescence.

One-pot in situ mixed film formation by azo coupling and diazonium salt electrografting.

So simple: The in situ synthesis of an aryldiazonium salt and an azo-aryldiazonium salt by azo coupling from sulfanilic acid and aniline is reported. Formation of a mixed organic layer is monitored by cyclic voltammetry and atomic force microscopy. A compact mixed layer is obtained with a global roughness of 0.

Electrochemically modified carbon and chromium surfaces for AFM imaging of double-strand DNA interaction with transposase protein.

Carbon and chromium surfaces were modified by electrochemical reduction of a diazonium salt formed in situ from the sulfanilic acid. The organic layer formed was activated by phosphorus pentachloride (PCl(5)) to form a benzene sulfonil chloride (Ar-SO(2)Cl). An electrochemical study of the blocking effect and the activity of this surface was carried out on a carbon electrode.

Polythiophene synthesis coupled to quartz crystal microbalance and Raman spectroscopy for detecting bacteria.

A simple electrochemical procedure was used for the synthesis of a polythiophene containing para-benzenesulfonyl chloride groups. The obtained polymer was shown to be very reactive and directly able to covalently bind nucleophile biomolecules. Protein A and a specific antibody were then successively immobilized on the conductive polymer through a covalent bonding of Protein A with the as-prepared linker for bacteria trapping purpose.

A simple method of surface functionalisation for immuno-specific immobilisation of proteins.

We present a new and advanced methodology, developed for surface functionalisation of gold and to study immobilisation of an immuno-specific system of proteins. A combination of electrochemical quartz crystal microbalance and Raman spectroscopy techniques allowed a complete understanding of the system starting from surface functionalisation and progressing to the functional structure analysis of immobilised proteins. A simple electrochemical procedure was formulated to prepare sulphonyl chloride terminated gold surfaces that form a strong sulphonamide bond with the receptor protein staphylococcal protein A (SpA).

Redox and ion-exchange properties in surface-tethered DNA-conducting polymers.

A poly(cyclopentadithiophene) matrix modified by DNA covalently fixed to the surface has been designed to study the redox and ion-exchange properties in surface-tethered DNA-conducting polymers. Voltammetric investigations show an improvement in conductivity, originating from DNA modification, probably due to changes in charged-density and size of dopant species. Cyclic voltammetry with concomitant QCM measurements indicate that the mass changes are consistent with an ejection of Na(+) cations associated to the anionic phosphate groups, attesting a DNA contribution to the p-doping process.

A poly(cyclopentadithiophene) matrix suitable for electrochemically controlled DNA delivery.

A conducting polymer is tested for DNA delivery trials. The conducting matrix used is successful for electrochemical delivery of DNA accumulated by covalent immobilization. The electrochemical process consists of the reduction of arylsulfonamide moieties, which occur as linker groups.

Use of telechelic cis-1,4-polyisoprene cationomers in the synthesis of antibacterial ionic polyurethanes and copolyurethanes bearing ammonium groups.

New crosslinked ionic polyurethanes and copolyurethanes were yielded by reaction of telechelic cis-1,4-oligoisoprenes, bearing a variable number of ammonium and hydroxy groups, with isocyanurate of isophorone diisocyanate (I-IPDI). Aiming for a comparative study, polyurethane elastomers based on non-ionic telechelic oligomers were also synthesized. Thermo-mechanical behavior and crosslinking density of these three families of materials were investigated by DMTA and swelling test, respectively.

Detection and modelling of DNA hybridization by EIS measurements. Mention of a polythiophene matrix suitable for electrochemically controlled gene delivery.

A conducting polymer sensor for direct label-free DNA detection based on a polythiophene bearing an electroactive linker group is investigated. DNA hybridization is studied by electrochemical impedance spectroscopy (EIS) and quartz crystal microbalance (QCM) techniques. Modelling of DNA hybridization by EIS measurements exhibits the contribution of nucleic acid to a superficial p-doping process.