Silver as antibacterial agent: Metal nanoparticles to nanometallopharmaceuticals: (Silver based antibacterial nanometallopharmaceuticals)

Because of increase in bacterial resistance to common antibiotics, antibacterial nanometallopharmaceuticals have been drawing increasing interest. Recent literature reports encouraging results about the bactericidal activity of silver nanoparticles of either a simple or composite nature. We, for the first time, demonstrated that silver nanoparticles (AgNP) undergo a shape dependant interaction with bacteria. We also developed highly antibacterial porous carbon matrices supporting nano-silver by simple and cost effective way. The antibacterial mechanism of the developed composite under prolonged incubation conditions was investigated against Escherichia coli. The application of silver in the treatment of burn wounds is of special interest, and has prompted an upsurge in research on the synthesis of antibacterial silver(I) complexes. However, the antibacterial performance of silver ion is correlated to its valence form and it has been found that the high valence silver ion exhibits stronger and more effective antibacterial action than low valence ion. Recently, we reported the synthesis of highly monodispersed nanoparticles of a trivalent silver polydiguanide complex in reverse microemulsion, demonstrating its flexibility for complexation reaction and the fabrication of essentially monodispersed nanoparticles of higher valent metal complex. The synthesized material showed strong antibacterial activity against the tested Gram (+)/(-) and methicillin-resistant Stahylococcus aureus strains. Interaction of polydiguanide ligands with silver at different oxidation states was also investigated. The in vitro pharmacodynamics of these complexes revealed that silver polydiguanide complexes provide faster killing kinetics compared to silver nitrate or polydiguanide ligands.