La chimie physique est l’étude des bases physiques des systèmes chimiques et des procédés. En particulier, la description énergétique des diverses transformations fait partie de la chimie physique. Elle fait appel à des disciplines importantes comme la thermodynamique chimique (ou thermochimie), la cinétique chimique, la mécanique statistique, la spectroscopie et l’électrochimie. Sont comptés parmi les phénomènes que la chimie physique essaie d'expliquer :

les forces intermoléculaires qui déterminent les propriétés physiques des matériaux, telles la déformation plastique des solides et la tension superficielle des solides ;

la cinétique chimique et la vitesse de réaction ;

les propriétés des ions et la conductivité électrique des matériaux ;

la chimie des surfaces et l'électrochimie des membranes ;

la thermochimie : le transfert de chaleur, et plus généralement les échanges d'énergie, entre un système chimique et son environnement lors d'une transition de phase ou d'une r

Surfactant-mediated interaction of fragrances with cellulose model surfaces

Mahtab Varnous

Odor perception may be considered from different perspectives: the physicochemical properties of odorants and target surfaces of interest, the biological aspects of electing odorant molecules by odorant receptors and their related downstream cellular signaling, and finally the physiological dimension of the sensing individual. This work concentrates on physico-chemical investigations, with the objective of developing novel analytical approaches to study in real time how odorant molecules together with their surfactant matrix interact with target surfaces of interest. Specifically the work presented in this thesis, deals with perfume-surfactant adsorption on cellulose model layers which should mimic the cotton fibres of fabrics. Surface sensitive attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy has been used to monitor the perfume-surfactant adsorption process. The thesis is structured as follows: The first part concerns the preparation of cellulose model surfaces. Cellulose layers with thicknesses in the range of 50-500 nm have been achieved by first spin coating of trimethysilylcellulose (TMSC) on silicon wafers or ATR-Ge crystals followed by a simple regeneration procedure. Physicochemical characterisation of these layers was performed by different techniques. The second part focuses on surfactant-perfume system. Multilamellar, sonicated and extruded vesicles of cationic surfactant dimethyldioctadecyl-ammonium chloride (DODAC), as commercially used in formulations containing fragrances, were prepared and used to entrap the perfumes. Theses vesicles were characterized by spectroscopic and microscopic techniques. Finally in the last part of this work, the adsorption and desorption kinetics of vesicles and fragrances on cellulose model surfaces are presented. The experiments were performed using an ATR-FTIR flow cell with different DODAC-perfume dispersions. The results obtained for adsorption of perfumes and surfactants to the cellulose model surfaces were compared with experiments performed on real cotton fabric.

EPFL2006

Development of Covalent Chitosan-Polyethylenimine Derivatives as Gene Delivery Vehicle: Synthesis, Characterization, and Evaluation

Sandrine Gerber, Céline Marie Anne Journot, Laura Camille Louise Nicolle

There is an increasing interest in cationic polymers as important constituents of non-viral gene delivery vectors. In the present study, we developed a versatile synthetic route for the production of covalent polymeric conjugates consisting of water-soluble depolymerized chitosan (dCS; MW 6–9 kDa) and low molecular weight polyethylenimine (PEI; 2.5 kDa linear, 1.8 kDa branched). dCSPEI derivatives were evaluated based on their physicochemical properties, including purity, covalent bonding, solubility in aqueous media, ability for DNA condensation, and colloidal stability of the resulting polyplexes. They were complexed with non-integrating DNA vectors coding for reporter genes by simple admixing and assessed in vitro using liver-derived HuH-7 cells for their transfection efficiency and cytotoxicity. Using a rational screening cascade, a lead compound was selected (dCS-Suc-LPEI-14) displaying the best balance of biocompatibility, cytotoxicity, and transfection efficiency. Scale-up and in vivo evaluation in wild-type mice allowed for a direct comparison with a commercially available non-viral delivery vector (in vivo-jetPEI). Hepatic expression of the reporter gene luciferase resulted in liver-specific bioluminescence, upon intrabiliary infusion of the chitosanbased polyplexes, which exceeded the signal of the in vivo jetPEI reference formulation by a factor of 10. We conclude that the novel chitosan-derivative dCS-Suc-LPEI-14 shows promise and potential as an efficient polymeric conjugate for non-viral in vivo gene therapy

2021

Surfactant-mediated interaction of fragrances with cellulose model surfaces

Mahtab Varnous

EPFL2006

Chimie physique

les forces intermoléculaires qui déterminent les propriétés physiques des matériaux, telles la déformation plastique des solides et la tension superficielle des solides ;

la cinétique chimique et la vitesse de réaction ;

les propriétés des ions et la conductivité électrique des matériaux ;

la chimie des surfaces et l'électrochimie des membranes ;

la thermochimie : le transfert de chaleur, et plus généralement les échanges d'énergie, entre un système chimique et son environnement lors d'une transition de phase ou d'une r

Surfactant-mediated interaction of fragrances with cellulose model surfaces

Physical properties of amourphous carbon films and their surfaces

Development of Covalent Chitosan-Polyethylenimine Derivatives as Gene Delivery Vehicle: Synthesis, Characterization, and Evaluation

Physical properties of amourphous carbon films and their surfaces

Surfactant-mediated interaction of fragrances with cellulose model surfaces

Development of Covalent Chitosan-Polyethylenimine Derivatives as Gene Delivery Vehicle: Synthesis, Characterization, and Evaluation