Madalina Tudose

Antibacterial Activity Evaluation of Silver Nanoparticles Entrapped in Silica Matrix Functionalized with Antibiotics

AbstractThis study reports the synthesis of silver nanoparticles (Ag NPs) by the sodium borohydride reduction method and their embedding in a silica shell functionalized with several antibiotics (ampicillin, penicillin G and isoniazide). The characterization of the novel materials was made by UV–visible absorption spectroscopy, transmission electron microscopy (TEM), Fourier transform infrared spectroscopy, dynamic light scattering and thermal analysis. TEM micrographs revealed the formation of spherical nanoparticles with size ranging between 20 and 50xa0nm. The Ag NPs embedded in the silica network exhibited a good antimicrobial efficiency, comparable or even superior to that of antibiotic-containing formulations. This is the first report regarding the synergic antimicrobial effect of Ag NPs embedded in silica and ampicillin, both against planktonic cells and biofilms formed by P. aeruginosa and S. aureus, two of the most fearful resistant bugs. These results are demonstrating the great potential of these nanocomposites to be used in developing novel antimicrobial agents or improving the existent ones, by increasing their efficiency, extending their spectrum of activity and decreasing the probability to select resistance, by simultaneously targeting multiple targets in the microbial cells.n

Lipoic acid functionalized SiO2@Ag nanoparticles. Synthesis, characterization and evaluation of biological activity

A novel nanocomposite was obtained through the covalent immobilization of lipoic acid on the surface of silver nanoparticles-decorated silica nanoparticles (SiO2@Ag). The hybrid organic - inorganic material obtained was characterized by Fourier transform infrared spectroscopy, thermal analysis, scanning and transmision electron microscopy, X-ray photoelectron spectroscopy and UV-Visible spectroscopy. Its antioxidant, cytotoxic, antimicrobial activity and influence on mammalian cells cycle were evaluated. The results of this study have shown that the functionalization of SiO2@Ag with lipoic acid resulted in a composite with increased specificity of interaction with different mammalian cell lines and antioxidant activity, but with decreased cytotoxicity and antimicrobial properties. Therefore, the SiO2@Ag functionalized with lipoic acid could be successfully used in certain concentrations to modulate the cell cycle, in order to obtain the desired anti-proliferative or stimulatory therapeutic effect.

New N-aryloxy-phthalimide derivatives. Synthesis, physico-chemical properties, and QSPR studies

AbstractStarting from N-hydroxyphthalimide 1 and the reactive fluoro- or chloro-nitroaryl derivatives 2, 3 and 4a-e (2-chloro-3,5-dinitropyridine; 3, NBD-chloride; 4a, 1-fluoro-2,4-dinitrobenzene; 4b, picryl chloride; 4c, 4-chloro-3,5-dinitrobenzotrifluoride; 4d, 2-chloro-3,5- dinitrobenzotrifluoride; 4e, 4-chloro-3,5-dinitrobenzoic acid) the corresponding N-(2-nitroaryloxy)-phthalimide derivatives 5a-e, or 6 and 7 were obtained and characterized by IR, UV-Vis 1H-NMR and 13C-NMR spectroscopy. The TLC behavior and the hydrophobicity of these derivatives have been experimentally evaluated by RM0 parameters (using RP-TLC). The experimental RM0 parameters were compared with the calculated partition coefficient, log P. A QSPR study was also performed to establish possible correlations between the structure and physical properties (λmax and RM0) of compounds 5a-e, 6, and 7.n