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A series of triorganylsilyl(β-dialkylaminoethoxy)silanes was prepared and characterized by elemental analysis, 1 H, 13 C, 29 Si NMR and mass spectroscopy. Comparative study of 29 Si resonance of newly synthesized compounds showed correlation between its value and substituent nature at the silicon atom, and is shifted upfield for β-triorganyl(N,N-dialkylaminoethoxy)silanes in comparison with corresponding methiodides, revealing weak N ... Si interaction for proper silanes. In vitro antitumour and antimicrobial properties were investigated. The biological activity data exhibited a marked enhancement of inhibitory activity on trialkylsilylation against tumour cell lines and all the test bacterial/fungal strains.

A series of N-methyl-N-(2-triorganylsiloxyethyl)-1,2,3,4-tetrahydro(iso)quinolinium iodides has been synthesized via dehydrocondensation reaction of N-(2-hydroxyethyl)-1,2,3,4-tetrahydroisoquinoline, N-(2-hydroxyethyl)-1,2,3,4-tetrahydroquinoline and 4,4-dimethyl-N-(2-hydroxyethyl)-4-sila-1,2,3,4-tetrahydroisoquinoline with trialkyl(aryl)hydrosilanes and subsequent alkylation, and characterized by 1 H, 13 C and 29 Si NMR and mass spectroscopy. The biological activity data exhibited a marked enhancement of inhibitory activity against tumour cell lines and almost all the test bacterial/fungal strains in comparison with their 2-hydroxyethyl precursors. Cytotoxicity in the microgram range against HT-1080 (human fibrosarcoma) and MG-22A (mouse hepatoma) cancer cell lines was observed for most of compounds.

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Magnetic nanoparticles represent an advanced tool in biomedicine because they can be simultaneously functionalized and guided using a magnetic field. Iron oxide magnetic nanoparticles precoated with oleic acid and bearing novel antimicrobial N-heterocyclic choline analogues, namely O-, N-and O,N-bis-undecyl-substituted N-(2-hydroxyethyl)-1,2,3,4-tetrahydroisoquinolinium derivatives, have been obtained as potential biomedical agents for drug delivery and antimicrobial therapy. Structural and size determinations for the novel synthesized magnetic nanosystems were carried out based upon magnetogranulometry, dynamic light-scattering measurements and X-ray diffraction analysis. The most expected iron oxide core diameter was 6.2-10.5 nm. The magnetization analyses showed that the particles are superparamagnetic at room temperature. Aqueous magnetic fluids of the synthesized nanoparticles were examined in vitro concerning Gram-positive (Staphylococcus aureus MSCL 334, Bacillus cereus MSCL 330) and Gram-negative (Escherichia coli MSCL 332, Pseudomonas aeruginosa MSCL 331, Proteus mirabilis MSCL 590) bacterial strains and fungi (Candida albicans MSCL 378, Aspergillus niger MSCL 324). It was found that the samples have magnetic properties and possess antimicrobial activity. The minimum inhibitory concentration against S. aureus for the most active magnetic fluid was determined as 16 μg ml À1.