Knowledge of the structure-activity relationship (SAR) allows for the possibility to design and synthesize new cationic amphiphiles with optimized antimicrobial activities for future development of new disinfectants, sanitizers or preservatives. The need to design and identify new compounds, possessing antimicrobial properties, results from the emergence of more resistant micro-organisms in our globalized society. Hitherto, most studies which analyse the biological activity of ionic liquids (ILs) investigate the effect of the cation, whereas the knowledge of the effect of the anion is limited. The present study confirms the existence of a strong relationship among structure, surface activity and biological action of imidazolium ionic liquids on bacteria and fungi. The dependence of the antimicrobial activity on chemical structure-chain length and anion type of 30 compounds was determined. The anion is an important structural element which partakes in the definition of the phyiscochemical properties of the IL, and in consequence the technological applications and mode of action of the compound. The introduction of a longer substituent on the imidazolium cation results in a lower minimal inhibitory concentration (MIC). Thus, antifungal and antibacterial activities were found to increase with chain length, very often up to a point exhibiting a cut-off effect at chain lengths of 16 or 18 for the imidazolium cation and the [Cl] anion. The efficiency of surface tension reduction circumscribed by the pC 20 and the relationship between antimicrobial activity and pC 20 is described herein. The relationship indicates an antimicrobial mode of action dependant on the surface activity of the molecule, inferring that surface activity may contribute to the cut-off effect in the biological activity of ILs.

A series of Ag-TiO 2 photocatalysts were obtained in microemulsion system (water/AOT/cyclohexane), using several Ag precursor amount ranging from 1.5 to 8.5 mol.%. The photocatalysts' characteristics by X-ray diffraction, STEM microscopy, UV-Vis spectroscopy, X-ray photoelectron spectroscopy, BET methods showed that a sample with the highest photo-and bioactivity had anatase structure, about 90 m 2 /g specific surface area, absorbed light for λ>400 nm and contained 1.64 at.% of silver (0.30 at.% of Ag 0 and 1.34 at.% of Ag 2 O) and about 13 at.% of carbon in the surface layer.The photocatalytic activity of the catalysts was estimated by measuring the decomposition rate of phenol in 0.21 mM aqueous solution under visible and ultraviolet light irradiation.The bioactivity of silver-doped titanium dioxide nanocomposites was estimated using

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Three structurally related oxathiolone fused chalcone derivatives appeared effective chemosensitizers, able to restore in part sensitivity to fluconazole of multidrug-resistant C. albicans strains. Compound 21 effectively chemosensitized cells resistant due to the overexpression of the MDR1 gene, compound 6 reduced resistance of cells overexpressing the ABC-type drug transporters CDR1/CDR2 and derivative 18 partially reversed fluconazole resistance mediated by both types of yeast drug efflux pumps. The observed effect of sensitization of resistant strains of Candida albicans to fluconazole activity in the presence of active compounds most likely resulted from inhibition of the pump-mediated efflux, as was revealed by the results of studies involving the fluorescent probes, Nile Red, Rhodamine 6G and diS-C3(3).

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