Preparation and antimicrobial behaviour of gemini fluorosurfactants.

The introduction of perfluorinated chains in the molecular structure of quaternary ammonium gemini surfactants have led to particularly active antimicrobial agents evaluated in this work. Connectors and spacers were studied in relation with antimicrobial activity in order to determine which molecular parameters are "critical" for biological activity.

Reverse water-in-fluorocarbon microemulsions stabilized by new polyhydroxylated nonionic fluorinated surfactants.

New polyhydroxylated nonionic perfluorosurfactants CnF2n+1-CH2-O-SO2-NHCONH-C(CH2OH)3 have been synthesized, and their capacity for stabilization of reverse water-in-fluorocarbon microemulsions has been extensively studied. These investigations showed that, regardless of the composition used, transparent one-phase systems could not be obtained if the fluorinated surfactants were used without a sufficient amount of a semifluorinated alcohol. The mixed oil phase used to prepare microemulsions consisted of a 9:1 mixture of perfluorohexane and 1H,1H,2H,2H-perfluorohexan-1-ol. Various scattering techniques, dynamic light scattering (DLS), small-angle X-ray (SAXS), and neutron scattering (SANS) have been used for structural characterization of these fluorinated microemulsions. Valuable information on the size, shape, and internal colloidal structure in these novel fluorinated microemulsions is described and discussed.

Preparation and antimicrobial behaviour of quaternary ammonium thiol derivatives able to be grafted on metal surfaces.

New thiol derivatives containing a quaternary ammonium group bearing variable hydrocarbon chains via an amide connector or not between the sulphur and nitrogen atoms were synthesised with the future aim to be grafted on metal surfaces for obtaining contact-active auto-bactericidal surfaces. Their biostatic and bactericidal activities were evaluated against four microbial strains (Pseudomonas aeruginosa, Staphylococcus aureus, Aspergillus niger and Candida albicans). The presence of the thiol and amide functions in these surfactants was discussed in relation with the antimicrobial activity along with the influence of the length of alkyl chains in order to determine which molecular parameters are 'critical' for biological activity, and consequently what molecules must be chosen for grafting on metal surface.

Fabrication of superhydrophobic PDMS surfaces by combining acidic treatment and perfluorinated monolayers.

In this paper, polydimethylsiloxane (PDMS) with a superhydrophobic surface was generated by the combination of an acid corrosion followed by the covalent grafting of a highly fluorinated monolayer. The acid corrosion was performed with H2SO4 or HF, and the more effective was concentrated H2SO4. The resulting surface had a contact angle with water of 135 degrees. All the acid-treated samples were then functionalized by the covalent grafting of triethoxyaminopropylsilane followed by the reaction with semifluorinated acid chlorides, via the formation of an amide bond, or directly by a commercially available highly fluorinated silane, 1H,1H,2H,2H-perfluorodecyltriethoxysilane, to afford superhydrophobic surfaces (contact angle with water exceeding 160 degrees). The introduction of an amide function in the fluorinated monolayer afforded the best water repellency properties probably due to the organization induced by H-bonding between the surface grafted molecules.

Synthesis and antimicrobial properties of polymerizable quaternary ammoniums.

Introduction of biocide monomers during the process of polymerization is a promising approach in the development of new permanent non leaching biocide materials. Two series of surfactants monomers, with a quaternary ammonium group as polar head and an acrylic function as the polymerizable moiety, were synthesized and tested to evaluate their surface active properties alongside with their antibacterial and antifungal properties. Four microbial strains were used to perform the study: Pseudomonas aeruginosa, Staphylococcus aureus, Candida albicans and Aspergillus niger. The biocidal efficacy measured by bacterial and fungal growth inhibition expressed as MIC (Minimal Inhibitory Concentration) and MLC (Minimal Lethal Concentration) values was discussed as a function of molecular parameters. All the synthesized surfactant monomers presented bactericidal and fungicidal activities. Increasing the spacer between the acrylic part and the ammonium group has a favourable effect on the MIC and MLC results.

Polymerizable semi-fluorinated gemini surfactants designed for antimicrobial materials.

Introduction of biocide monomers during the process of polymerization is one of promising approaches in the development of new permanent non leaching biocide materials. In this perspective, new polymerizable semi-fluorinated gemini surfactants, with quaternary ammonium groups as polar heads and an acrylic function as the polymerizable moiety, were synthesized and tested to evaluate their surface active properties alongside with their antibacterial and antifungal properties. Four microbial strains, known for their implication in nosocomial infections, were used to perform the study: Pseudomonas aeruginosa, Staphylococcus aureus, Candida albicans and Aspergillus niger. The biocide efficacy measured by bacterial and fungal growth inhibition expressed as MIC (minimal inhibitory concentration) and MLC (minimal lethal concentration) values was discussed as a function of molecular parameters. As compared to homologue compounds without acrylic part, this study shows that even the introduction of a polymerizable moiety allows to keep remarkable both surfactant and bacteriostatic activities, and allows us to envisage the use of these surfactant monomers to build up advanced biocide materials. Moreover, semi-fluorinated gemini surfactant monomers with an amide connector came out as broad spectrum biocides (against Gram positive and negative bacteria and fungi).

Contact-active microbicidal gold surfaces using immobilization of quaternary ammonium thiol derivatives.

Contact-active auto-bactericidal surfaces were obtained by grafting of specially designed thiol derivatives containing antimicrobial quaternary ammonium moieties on gold substrates. The formation and quality of the self-assembled monolayers (SAMs) were characterized by X-ray photoelectron spectroscopy, cyclic voltammetry and contact angle measurements. The bactericidal activity of the modified gold surface was evaluated against Staphylococcus aureus using an original procedure. This activity was demonstrated to be dependent on the length of the alkyl chain borne by the charged nitrogen atom of the quaternary ammonium moiety, and on the contact time.

Novel highly fluorinated sulfamates: synthesis and evaluation of their surfactant properties.

Two synthetic pathways have been elaborated to prepare new series of highly fluorinated sulfamates with excellent yields. Surface tension measurements at the air/water interface showed that these compounds constitute new excellent non-ionic surfactants exhibiting high surface activity in the range of the best non-ionic fluoro surfactants already described in the literature. The most important feature of this work is that, in comparison with the classical non-ionic fluoro surfactants, these sulfamates are easily synthesized in a monodisperse form from classical and relatively non-toxic starting materials. The critical micelle concentration (CMC), the maximum surface excess concentration (Gamma) and the minimum area per molecule (a) have been calculated from the surface tension measurements on surfactant aqueous solutions. Relationships have been established between the length of both the fluorinated tail and hydrocarbon spacer linking the hydrophobic tail to the hydrophilic head, and the interfacial properties.

2-DE using hemi-fluorinated surfactants.

The synthesis of hemi-fluorinated zwitterionic surfactants was realized and assessed for 2-DE, a powerful separation method for proteomic analysis. These new fluorinated amidosulfobetaine (FASB-p,m) were compared to their hydrocarbon counterparts amidosulfobetaine (ASB-n) characterized by a hydrophilic polar head, a hydrophobic and lipophilic tail, and an amido group as connector. The tail of these FASB surfactants was in part fluorinated resulting in the modulation of its lipophilicity (or oleophobicity). Their effect on the red blood cell (RBC) membrane showed a specific solubilization depending on the length of the hydrophobic part. A large number of polypeptide spots appeared in the 2-DE patterns by using FASB-p,m. The oleophobic character of these surfactants was confirmed by the fact that Band 3, a highly hydrophobic transmembrane protein, was not solubilized by these fluorinated structures. The corresponding pellet was very rich in Band 3 and could then be solubilized by using a strong detergent such as amidosulfobetaine with an alkyl tail containing 14 carbon atoms (ASB-14). Thus, these hemi-fluorinated surfactants appeared as powerful tools when used at the first step of a two-step solubilization strategy using a hydrocarbon homologous surfactant in the second step.

Stable superhydrophobic and lipophobic conjugated polymers films.

With a view to developing repellent materials combining both low surface energy and rough structure, original semi-fluorinated polythiophenes have been chemically and electrochemically synthesized and characterized by cyclic voltammetry, GPC, and UV-visible measurements. Polymer films have been deposited onto different substrates by drop casting a soluble polymer fraction on glass plate or by electrodeposition on ITO plate. Surface properties and particularly water and oil repellencies have been investigated by goniometry and correlated with the surface morphology and structure observed by SEM. The incorporation of fluorocarbon chains in the rigid polythiophene backbone yields very low surface free energy materials. Moreover, the way of deposition has a huge influence on the quality and performance of the film surface properties. Electroformed polymers, due to rough surfaces, exhibit great super-hydrophobic and lipophobic properties together with exceptional time stability.