RESUMO
The regular arrangement of complementary diaminopyridine-thymine (DAP-THY) on alternating copolymers permits cooperative binding events and the effective formation of well-controlled micrometre-scale aggregates.
Assuntos
Aminopiridinas/química , Polímeros/síntese química , Timina/química , Ligação de Hidrogênio , Conformação Molecular , Peso Molecular , Compostos Organometálicos/química , Polímeros/químicaRESUMO
Amphiphilic cationic polynorbornene derivatives, soluble in water, were prepared from modular norbornene monomers, with a wide range of molecular weights (M(n) = 1600-137 500 g/mol) and narrow polydispersities (PDI = 1.1-1.3). The antibacterial activity determined by growth inhibition assays and the hemolytic activity against human red blood cells were measured and compared to determine the selectivity of the polymers for bacterial over mammalian cells. The effects of monomer repeat unit hydrophobicity and polymer molecular weight on antibacterial and hemolytic activities were determined. The hydrophobicity of the repeat unit was observed to have dramatic effects on antibacterial and hemolytic activities. Lipid membrane disruption activities of the polymers was confirmed by measuring polymer-induced dye leakage from large unilamellar vesicles. By tuning the overall hydrophobicity of the polymer through random copolymerizations of modular norbornene derivatives, highly selective, nonhemolytic antibacterial activities were obtained. For appropriate monomer composition, selectivity against bacteria versus human red blood cells was determined to be over 100.
Assuntos
Antibacterianos/química , Antibacterianos/farmacologia , Eritrócitos/efeitos dos fármacos , Norbornanos/química , Norbornanos/farmacologia , Bacillus subtilis/efeitos dos fármacos , Membrana Celular/efeitos dos fármacos , Colesterol/química , Escherichia coli/efeitos dos fármacos , Hemólise , Humanos , Lipossomos/química , Testes de Sensibilidade Microbiana , Peso Molecular , Polímeros/química , Polímeros/farmacologia , Relação Estrutura-AtividadeRESUMO
Cadmium selenide nanoparticles, prepared by known methods, were stabilized with functional phosphine oxide 1, then used to support the polymerization of cyclic olefins radially outward from the surface by ruthenium-catalyzed ring-opening metathesis polymerization (ROMP). The conversion of compound 1 into the new metathesis catalyst 3 by carbene exchange and the subsequent polymerization of cyclic olefins were observed spectroscopically by (1)H NMR to afford for example CdSe-polycyclooctene composite 6. Transmission electron micrographs on thin films of these composites showed good nanoparticle dispersion. This is in stark contrast to the substantial nanoparticle aggregation observed when similar polymerizations were performed in the presence of conventional TOPO-covered nanoparticles. The methods reported here to prepare composite product 6 are applicable to other cyclic olefins, and suggest that this chemistry will be useful for incorporating CdSe nanoparticles into a wide variety of polymer matrices.